Repair of magnetic starters. Functional testing and maintenance
Introduction………………………………………………………………………………………...3
1. Characteristics of the work, and what a third-rate electrician should know……………………........ ........................................................ ...............4
2. Repair and maintenance of electrical equipment……………………………6
2.1. Starters………………………………………………………………………………6
2.2. Thermal relays………………………………………………………………………………..8
2.3. Contactors……………………………………………………………….10
2.4. Repair and adjustment of contacts and mechanical parts of the contactor...13
3. Soldering wires…………………………………………………………15
3.1. Safety precautions when soldering…………………………………………..17
4. Installation of fluorescent lamps………………………………………………………...23
Conclusion………………………………………………………………………………….24
References……………………………………………………………25
Repair and maintenance of electrical equipment
Starters
A magnetic starter is essentially a switching device whose task is to connect and disconnect the load from the network. Such devices are widely used mainly in industry and control of electric motors, but a wide range of rated currents and small dimensions of the device also make it possible to effectively find applications in everyday life. In magnetic starters, moving or stationary elements and arcing contacts most often fail.
When the starter operates intensively, metal deposits, as well as soot and oxides, form on the contact plates of the device. All this is cleaned using a fine-cut file or needle file. After a good cleaning, the contacts are washed with a cloth that can be soaked in white spirit or can also be used in aviation gasoline. But still, it is better to avoid this procedure in working starters, since the current-conducting layer on the contacts of the device is quite thin and each “preventative cleaning” will reduce it.
The contact planes of the armature and the core are cleaned with a soft rag soaked in alcohol. After cleaning with a 0.05 mm wide probe or a narrow piece of paper, you need to check the contact area between the core and the armature by pressing the armature against the core with your hand. The contact plane must be more than 70% of the core cross-section. If this gap is less than 0.2 mm, the armature or starter core must be clamped in a vice and the central core must be cut off using a file. The value of this gap must be within 0.2 - 0.25 mm.
Often a hum (hum) is heard during operation of the device; there may be several reasons. First of all, you need to inspect the cracks on the coil frame; perhaps there is a misalignment of the coil itself, or the return spring is too powerful. All this can lead to the fact that the armature does not adhere closely enough to the core when closing. The consequence will be a higher coil current due to its lowest inductive resistance (hence the hum), as well as burning of the power contacts.
Failure of the coil itself is also likely; they come in both frame and frameless. If there is a defect in the coil insulation or a break in the winding electrical wire in the upper layers of the winding, remove the external insulation of the winding and the warped turns to the point of the defect or break, solder it further, insulate the soldering area of the new winding electrical wire and wind the required number of turns. Although sometimes when the coil defects are significant, interturn short circuits, winding insulation burns, it is much better to replace the coil with a new one. Sometimes, when closing the contacts, the plates close at different times, you can try to fix it by tightening the clamp holding the main contacts on the shaft. If the surface of the magnetic plates has damage and defects, clean it with a soft cloth soaked in gasoline or white spirit and dry it. And after drying, the core and the anchor are lowered into a bath of enamel so that the contact surfaces are not covered with varnish, and the width of the unpainted belt around the edges of the contact surface should be no more than 3 mm. You can also varnish the armature and the core of the magnetic circuit using a brush. After painting, the magnetic circuit is dried in the open air for 3 hours until completely dry.
Thermal relays
Repair of thermal relays and circuit breakers. Damage to individual elements of a thermal relay (wear, deformation and breakage of parts; burning of contacts) leads to disruption of its operation modes. Therefore, an important point in restoring the functionality of the thermal relay is its adjustment. The relay is tested with load current.
(Fig. 138) and take its characteristics in the form of a relationship between the operating current and the shutter speed (both without preheating and after heating with the rated current). By comparing the obtained characteristics with the control ones, they determine whether the relay meets the specifications or repeat the experiment by changing the position of the adjustment lever. Automatic switches AP-50, A3100, AE-2000 and others are produced with thermal and electromagnetic separators. The operation of circuit breakers is checked in a similar way to checking the operation of a thermal relay using appropriate load circuits and control characteristics for each type of switch. The main malfunctions of mechanical parts (wear and burning of contacts and clamping terminals, wear of the rubbing surfaces of levers and rods, weakening and breakage of springs) are eliminated by the operations used in the repair of the previously discussed start-protection and control devices.
It is recommended to check and adjust thermal relays in the laboratory using special electrical devices. Checking the relay begins with an external inspection: checking the presence of seals, the integrity of the casing and its tight fit to the base, the condition of the seals, and cleaning the relay.
After removing the casing, they begin an internal inspection: clean the parts, check the tightness of screws, nuts, fastening springs, contacts, bearings, magnetic circuits; check the reliability of internal connections; adjust the mechanical part of the relay; contacts are thoroughly cleaned and polished. (do not use a file or abrasive materials).
Next, measure the insulation resistance with a 1000 V megohmmeter between the electrical parts of the relay and the housing, which must be at least 10 MOhm, and check the settings. If defects are found that are beyond the ability to eliminate them in the laboratory, the relay is replaced with a new one.
When repairing magnetic starters with thermal relays, attention should be paid to the integrity and condition of these relays. In thermal relays, heating elements most often fail (burn out). These elements have different designs and come in 6 types, designed for different currents. Elements of the first and second types are made of nichrome or fechral wire. In elements of the first type, the wire is wound on a mica plate and copper tips are soldered with silver to the ends of the wire. In elements of the second type, the wire is wound in the form of a spiral; steel tips are soldered to its ends. Spiral elements are cadmium plated to protect them from oxidation. Elements of the other four types are produced by stamping.
For thermal relays, there must be clear operation at a current of 1.5 Inom with a time delay of 20 minutes, at a current of 1.2 Inom and for an hour at a current of 1.05 Inom. The relay return time should be no more than 3 minutes after it is turned off.
Contactors
Repair of electromagnetic contactors during routine repairs is carried out with their complete disassembly. It is convenient to produce it on special stands with an air supply and direct current voltage 50V for testing repaired devices. On such a stand, each contactor is installed in a socket, which allows you to quickly secure the stand and freely rotate the device in a horizontal plane during disassembly and assembly. Before disassembling, the contactors are blown with compressed air, the arc-extinguishing chamber is removed and the components and parts are inspected to determine the scope of repair. All parts are cleaned of dirt, disassembled and inspected, making sure there are no cracks. The horn of the arc extinguishing system is cleaned of melts and soot with a metal brush or emery cloth. The horn profile is checked using a template and, in case of large melts or cracks, it is restored by gas welding. After the arc horn has cooled, the welding seam is cleaned with a file. Contacts with slight wear or with burns are cleaned with a velvet or personal file, trying to remove as little metal as possible and not change the contact profile. After cleaning, wipe the contacts with a rag. The places of contact resistance with the horn are served with solder. Contacts worn beyond acceptable limits can be restored. In this case, the worn contacts, after cleaning and measurements, are fused with copper using gas welding. The contacts are preheated with a gas burner, after which their working surfaces are fused. The deposited contacts are tapped with a hammer and processed to impart hardness. The dimensions of the contact profile are controlled by templates. The arcing coil is checked for the absence of damage to the surface insulation and for the reliability of soldering of the cable lugs; measure the active resistance of the winding and the insulation resistance between the winding and the poles, which must be at least 10 MΩ. If the insulation resistance is low, the coil is dried in an oven at a temperature of 100-110 ° C or the insulating sleeve of the core is replaced. The cross-sectional area of the wire and the number of turns of the arc suppression coil must comply with the technical requirements of the drawing. If this condition is not met, there may be an incorrect direction of the magnetic blowing of the electric arc, which leads to severe burns of the arc extinguishing horns and contacts. The arcing coil of the contactor with cracks in the turns is replaced. When installing a new coil, the contact terminal is welded with brass, after first fitting the mating surfaces well to each other. After this, the junction with the turns is insulated into the half-roof with two layers of varnished fabric and insulating tape. The coil turns are painted, if necessary, with BT-99 oil-bitumen varnish. The turns should not touch each other and come closer than 2 mm to the arc extinguishing horn.
The switching coil of the contactor is washed with gasoline and inspected for looseness of the output clamps, the external insulation and the condition of the frame are checked. To identify possible wire breaks, measure the active resistance of the coil with a megohmmeter. It should not deviate from the established one by more than 8% upward or 5% downward. If the coil resistance increases beyond the permissible value, it will indicate a possible internal break in the winding or deterioration of the contact between the winding terminal core and the tip. Coils with reduced insulation resistance are impregnated.
Repair of coils with their complete disassembly is carried out in the presence of broken conductors or interturn short circuits. If the coil insulation is damaged, then repairs are limited to only changing the insulation. For coils, it is allowed to restore two winding breaks. The ends of the winding wires at the break points are cleaned, bunched together and soldered with POS-40 solder. Coils with melted turns of more than 3% of their cross-sectional area or with cracked tires must be repaired. Burnouts, melts or cracks are cleaned and welded with brass using gas welding. For deeper burns, the coils are replaced. Reels that have undergone repair are impregnated with varnish. Damaged terminal braiding is sealed with rubberized adhesive tape. The armature magnetic circuit and core are washed from dirt and, if necessary, galvanized. The bushings with developed holes in the contact holder, the armatures are pressed out and new ones are installed. The axles and rollers are cleaned of dirt, scorch, and burns, galvanized and lubricated before installation.
Arc chamber
The arc-extinguishing chamber removed from the contactor is purged with compressed air, cleaned of soot, burns and metal splashes and disassembled. Asbestos-cement walls, partitions and gratings are cleaned using a steel blasting machine or installation. Walls with a thickness of less than 4 mm, with chips, cracks and burnouts with a depth of more than 25% of their thickness are replaced. Places of deeper cracks and burns are cut out, thoroughly cleaned with a file, coarse sandpaper or treated in a sandblasting chamber, cleaned of dust and sand and sealed with special putty or epoxy resin.
As a putty, asbestos-cement powder diluted with liquid glass, or a mixture of equal parts of gypsum powder and asbestos fiber on an alkaline varnish, is used. The putty is applied so that its level is slightly higher than the surface being repaired, since it shrinks as it hardens. putty on liquid glass dried at a temperature of 25-30°C, and alkaline - in a drying oven at a temperature of 70-80°C for 7-8 hours. Through burns and cracks can be eliminated with special mastic. The putty is applied immediately after its manufacture, since its polymerization process quickly begins and after 30-40 minutes. it is already hardening. Before applying mastic, the area to be repaired is thoroughly degreased with acetone or gasoline. After final processing, to increase moisture resistance, asbestos-cement walls and partitions are impregnated with linseed oil. After making sure that all parts are in good working order, the camera is assembled.
Insulating strips and base panels, levers, racks must have a clean glossy surface or be painted with GF-92-ХК enamel.
Surface insulation that has cracks, chips, burns or damage up to half its thickness is removed completely or partially. Small burns are cleaned with a file and polished with fine glass paper. The area to be repaired is washed with gasoline and coated with enamel twice. The springs are removed, washed and checked for basic dimensions. Springs with traces of rust are galvanized and then dehydrated. Springs that are stretched or sagging, but have no mechanical damage, are restored. To do this, the spring is released, heated to a temperature of 920-980°C, compressed or stretched to the drawing dimensions and subjected to hardening to impart the necessary elasticity. The end screws of the spring must have a flat horizontal surface. Springs with cracks and not meeting specifications are replaced.
Swivel joints.
They must ensure free movement of the connected parts without jamming and not have increased backlash.
For repairs, the hinge joint is disassembled. Faulty axles and rollers are not repaired, but replaced with new ones. The developed holes are welded and drilled to the drawing size or to a larger diameter, followed by installation of a bushing with the corresponding internal and external diameters.
Before assembly, the rubbing surfaces of the hinge joints are coated with lubricant, and after assembly the clearance in the hinge is controlled.
After repairing all components and parts, the contactor is reassembled in reverse disassembly sequence.
Repair and adjustment of contacts and mechanical parts of the contactor
Before repairs, all major parts of the contactor are inspected to determine which parts need to be replaced and rebuilt. It is best to use factory spare parts and only make new ones if they are unavailable. Repair of contactors comes down primarily to restoring contacts. If the contact surface is slightly burned, it is cleaned of soot and deposits with an ordinary personal file and glass paper. Cleaning must be done carefully, removing a small layer of metal. It is not recommended to lubricate contact surfaces, since when an arc occurs, the lubricant burns and contaminates the surface, worsening the operating conditions of the contact. However, if the surface of the contacts is covered with a layer of silver, it is not recommended to clean them with a file. If the contacts are severely burned, they must be replaced. For the manufacture of contacts, copper cylindrical or shaped rods made of solid copper of grade M-1 are used.
Contacts in the form of rivets, screws, bolts and nuts are made by turning on lathes, turret lathes or screw-cutting lathes. The profiles of new contacts of contactors and controllers for smooth rolling of the contact must strictly correspond to the surface profile of the contact being replaced.
When making these contacts, the rod is clamped in a machine vice or a special device with jaws of a given profile and cut into the required sections on a horizontal milling machine. During this operation, it is important to ensure parallelism of the sides and the exact size of the width of the cut profile (±0.2); The burrs formed on the workpiece are filed with a file and only after that the workpiece is drilled or threaded.
After repairing the contact system, it is adjusted. Adjusting the operation of the contact system is one of the most important repair operations, on which the normal operation of the device depends. Contacts for various purposes must be turned on and off in the prescribed sequence, and contacts of phases performing the same function must operate simultaneously. If, during the adjustment process, the initial pressures with new contacts do not fall within the factory-standardized limits, it is necessary to change the corresponding contact springs. The degree of contact pressing is checked in two positions - when they are open (initial pressing) and when they are closed (final pressing).
When repairing contactors, adhere to the rated contact pressure values. Deviation from them in one direction or another can lead to unstable operation of the contactor, causing it to overheat and weld the contacts.
A magnetic starter is essentially a switching device whose task is to connect and disconnect the load from the network.
Such devices are widely used mainly in industry and control of electric motors, but a wide range of rated currents and small dimensions of the device also make it possible to effectively find applications in everyday life.
In magnetic starters, moving or stationary elements and arcing contacts most often fail.
What is a magnetic starter?
First of all, to begin with, this is a coil, usually made of thin wire, wound on a textolite body with a metal core inside, placed in a kind of plastic case with contacts. The contacts in the device are divided into movable, mechanically connected to a spring-loaded coil core, and fixed, permanently placed in the upper part of the housing.
When the starter operates intensively, metal deposits, as well as soot and oxides, form on the contact plates of the device. All this is cleaned using a fine-cut file or needle file. After a good cleaning, the contacts are washed with a cloth that can be soaked in white spirit or can also be used in aviation gasoline.
But still, it is better to avoid this procedure in working starters, since the current-conducting layer on the contacts of the device is quite thin and each “preventative cleaning” will reduce it.
The contact planes of the armature and the core are cleaned with a soft rag soaked in alcohol. After cleaning with a 0.05 mm wide probe or a narrow piece of paper, you need to check the contact area between the core and the armature by pressing the armature against the core with your hand.
The contact plane must be more than 70% of the core cross-section. If this gap is less than 0.2 mm, the armature or starter core must be clamped in a vice and the central core must be cut off using a file. The value of this interval must remain within 0.2 - 0.25 mm.
Often during operation of the device a hum is heard, there may be several reasons. First of all, you need to inspect the cracks on the coil frame; perhaps there is a misalignment of the coil itself, or the return spring is too powerful.
All this can lead to the fact that the armature does not adhere closely enough to the core when closing. The consequence will be a higher coil current due to its lowest inductive resistance (hence the hum), as well as burning of the power contacts.
Failure of the coil itself is also likely; they come in both frame and frameless.
At defective coil insulation or breakage of the winding electrical wire in the upper layers of the winding, remove the external insulation of the winding and the warped turns to the point of the defect or break, add solder, insulate the soldering area of the new winding electrical wire and wind the required number of turns.
Although sometimes when the coil defects are significant, interturn short circuits, winding insulation burns, it is much better to replace the coil with a new one.
Sometimes when contacts are closed it happens different timing of plate closure, you can try to fix it by tightening the clamp holding the main contacts on the shaft.
If the surface magnetic plates It has damage and defects, it is cleaned with a soft cloth soaked in gasoline or white spirit and dried. And after drying, the core and the anchor are lowered into a bath of enamel so that the contact surfaces are not covered with varnish, and the width of the unpainted belt around the edges of the contact surface should be no more than 3 mm. You can also varnish the armature and the core of the magnetic circuit using a brush. After painting, the magnetic circuit is dried in the open air for 3 hours until completely dry.
Having identified all the malfunctions of the magnetic starter, you can simply replace some parts with new ones; such elements can be coils, springs, clamping plates, as well as contacts and entire contact groups.
March 24, 2011When repairing a magnetic starter, clean the contacts and check the integrity of the bimetallic elements and heaters. Failed elements are replaced with new factory-made ones.
One of the most frequently damaged parts of a magnetic starter is its holding coil, which flows current around it when the starter is turned on. The coil with insulation that has dried out due to long-term operation is replaced with a new one.
If there are no factory-made coils, they are wound in the electrical shop of the enterprise, guided by the winding parameters given in the table, the dimensions of the damaged coil, as well as the above description of the method of winding contactor coils.
Parameters of coil windings of magnetic starters
| Magnetic starter size | Types of magnetic starters | Voltage, in | |||||
| 127 | 220 | 380 | |||||
| Wire diameter, mm | Number of turns | Wire diameter, mm | Number of turns | Wire diameter, mm | Number of turns | ||
| 2 | P-211; P-212; P-213: P-214; P-221; P-222; P-223; P-224 | 0,25 | 1600 | 0,20 | 2700 | 0,15 | 4700 |
| 3 | P-311; P-312; P-313; P-314; P-321; P-322; P-323; P-324 | 0,31 | 1220 | 0,25 | 2120 | 0,20 | 3650 |
| 4 | P-411; P-412; P-413; P-414; P-421; P-422; P-423; P-424 | 0,83 | 490 | 0,64 | 850 | 0,47 | 1470 |
| 5 | P-511; P-512; P-513; P-514; P-521; P-522; P-523; P-524 | 1,16 | 400 | 0,86 | 700 | 0,64 | 1200 |
Thermal relays often have heating elements that fail. Relay elements built into magnetic starters are manufactured in six types, designed for different current values. Elements of the first and second types are made of nichrome or fechral wire.
In elements of the first type, the wire is wound on a mica plate, and copper tips are soldered to the ends of the wire with silver.
In elements of the second type, the wire is wound in the form of a spiral, and steel tips are soldered to its ends. The spiral elements are cadmium coated to protect them from oxidation when heated. Elements of the other four types are produced by stamping.
To ensure reliable operation of the magnetic starter during repairs, factory-made heating elements are used and only in exceptional cases are new elements manufactured at their own enterprises.
“Repair of electrical equipment of industrial enterprises”,
V.B.Atabekov
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Hidden laying of flat wires is carried out under a layer of wet or dry plaster, in channels and grooves. Furrows in walls and ceilings, as well as holes and sockets for hidden wiring, are punched with special electrified tools. For drilling deep holes, use an electric drill with a drill attachment, and for drilling slots for boxes - with a crown attachment. Device for making furrows Device for…
The contactor is controlled as follows. When voltage is applied to the circuit, the coil attracts an armature, which, turning at a certain angle, presses the movable contacts located on the same shaft with the stationary ones. When the current circuit is broken, the coil ceases to hold the armature, as a result of which the movable contact system, under the influence of its own weight and the weight of the armature, falls away, the main contacts open, breaking the electrical...
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INTRODUCTION
Scientific and technological progress occurs with more and more widespread use electrical energy. In our time, there is not a single branch of the national economy, not a single scientific research work, where it is not used in one way or another. The use of electricity became possible with the advent of electrical engineering - the science of the practical application of electrical and magnetic phenomena of nature and the laws that describe them.
Electrical engineering and electronics have occupied a vital place in the life of modern society, since in industry, transport, agriculture, everyday life, medicine, and culture they contribute to a radical change in the economic and social conditions of human life.
Further mechanization and automation of processes at enterprises, the supply of new, more complex high-performance machines and units, requires electrical installers not only to reduce commissioning time, but also to provide quality work that ensures high reliability, durability and safety in servicing electrical installations.
In the conditions of intense work of enterprises, repairs of electrical equipment must be carried out in an extremely short time, which is possible with a high level of organization repair work. Since the needs of enterprises for transformers, electrical machines and apparatus are not yet fully satisfied, timely and high-quality repairs of this electrical equipment have become one of the main factors ensuring the normal operation of enterprises.
During the repair process, it is possible to modernize electrical equipment, change it in the right direction technical characteristics, increasing operating efficiency.
Long-term practice of electrical repair shops of enterprises and electrical repair plants has shown that over 70% of damaged electrical equipment received for repair are transformers, electrical machines and switching devices, in the repair of which electrical plumbing work plays a significant role.
In my work, I examined the issues of maintenance and repair of magnetic starters.
1. PURPOSE AND DESIGN
Electromagnetic starters are intended for use in stationary installations for remote starting by direct connection to the network, stopping and reversing three-phase asynchronous electric motors with a squirrel-cage rotor of alternating voltage 660 V, frequency 50 and 60 Hz. In the presence of three-pole thermal relays of the RTT and RTL series, the starters protect controlled electric motors from overloads of unacceptable duration and from currents arising when one of the phases is broken. The starters are suitable for operation in control systems using microprocessor technology when the switching coil is bypassed with an interference suppression device or with thyristor control.
Designed for remote start by direct connection to the network and shutdown of three-phase asynchronous electric motors with a squirrel-cage rotor. Additional functions: reversing, in the presence of thermal relays - protection of motors from overloads of unacceptable duration, including those arising when one of the phases fails, changing the circuit diagram for switching on the Y/A windings.
1.1 TECHNICAL SPECIFICATIONS
The most common starters are the PME and PAE series. They are used to control electric motors with power up to 75 kW. The designations of the starters are deciphered: PME - series, the first digit after the series is the value (0 - zero, 1 - first, 2 - second), the second digit - version (1 - open, 2 - protected, 3 - dust-proof, 43 - with four closing block contacts, 5 - protected, 43+2Р - with four normally open and 2 normally closed block contacts, b - dust and waterproof, 7 - open). The third number is the possibility of reversing and the presence of thermal protection (1 - non-reversible and without a thermal relay, 2 - non-reversible with a thermal relay, 3 - reversible without a thermal relay, 4 - reversible with a thermal relay).
The table clearly shows which types of starters can be replaced with each other without damage to the equipment. The table shows data on replacing PMA, PML, PME starters with starters of the PM12 series
Table 1 - Technical data of magnetic starters of the PME series
2. Design and principle of operation
Magnetic starters provide protection for electric motors against voltage drop (zero protection) and overload. When the voltage drops to 35-40% of the nominal value, the retractor coil ceases to hold the electromagnet armature and the starter contacts open. Overload protection is carried out using thermal relays TRN, TRP, RTT, RTL.
Electromagnetic starter - a switching electrical device designed for starting, stopping and protecting three-phase asynchronous electric motors with a squirrel-cage rotor
The main, and sometimes the only element of the starter is a three-pole electromagnetic AC contactor, with which the main parameters of the starter are associated: Rated voltage and rated current of the switched circuit, switching capacity, switching and mechanical wear resistance.
In accordance with GOST 2491-82, starters are intended for operation in the AC-3 application category and must allow operation in the AC-4 application category.
The switching durability of devices in these categories is tested under conditions simulating the switching on and off of an asynchronous motor, corresponding in parameters to the nominal data of the starter, in modes determined by the category of application of the starter.
As an element of automatic control systems, starters are subject to high wear resistance requirements. Starters are produced in three classes of switching wear resistance (A, B and C).
The highest wear resistance is for devices classified as class A, the lowest for devices classified as class B. Switching and mechanical wear resistance for devices classified in different classes is indicated in the technical data of devices of specific types.
The switching wear resistance class is selected depending on the required service life and the expected frequency of operation in the AC-3 application category.
Starters must operate in one or more of the following modes: continuous, intermittent-continuous (8-hour), intermittent, short-term.
Starters are available in versions with varying degrees of protection against contact and external influences (IPOO, IP 20, IP 30, IP 40, IP 54).
To connect a magnetic starter you need to understand its operating principle, study design features. Then, despite the apparent complexity of the connection diagram, it will not be difficult for you to connect the starter correctly, even if you have never had to deal with magnetic starters before.
three-phase coil starter electromagnet
3. TECHNICAL CONDITIONS
Technical conditions (TU) - a document establishing technical requirements, which must be satisfied by a specific product, material, substance, etc. or a group of them. In addition, they must specify procedures by which to determine whether these requirements have been met.
Specifications are a technical document that is developed by decision of the developer and/or manufacturer or at the request of the customer (consumer) of the product. Specifications are an integral part of the design kit or other technical documentation for products, and in the absence of documentation must contain a full range of requirements for products, their manufacture, control and acceptance.
Technical specifications are developed for one specific product, material, substance or several specific products, materials, substances, etc. (then an OKP code is indicated for each product, material, etc.) The requirements established by the technical specifications must not contradict the mandatory requirements state or interstate standards applicable to these products. The composition, construction and execution of technical specifications must comply with the requirements of GOST, included in the ESKD system.
Technical conditions and standards in accordance with the law on technical regulation are not mandatory for the production of products with the exception of a number of types of products, for example technical devices, used at hazardous production facilities.
Since the times of the USSR, it has changed its meaning.
Designation TU.
For mechanical and instrument engineering products, technical specifications are designated, like other non-basic design documents, according to GOST 2.201 (three groups of signs separated by dots, with the document code at the end):
· four-digit letter code of the developing organization (or a code allocated during the centralized assignment of the designation);
· six-digit digital code of classification characteristics assigned to the product and design document according to OKP;
· document code according to GOST 2.102 - “TU”.
Example: ABVG.123456.789TU, where ABVG is the code of the development organization, 123456 is the product code according to the ESKD classifier, 789 is the serial registration number.
For materials, substances, etc., it is recommended to formulate the designation of technical conditions as follows: code “TU”, then 4 groups of numbers separated by hyphens:
· product group code according to the product classifier of the country that developed the technical specifications (in Russia - the first four digits according to the All-Russian Product Classifier);
· three-digit digital serial number assigned by the developer;
· code of the enterprise of the developer of technical specifications according to the classifier of enterprises of the country that developed the technical specifications (in Russia - according to the All-Russian Classifier of Enterprises and Organizations);
· two (since 2000 - four) last digits of the year the document was approved.
Example: TU 1115-017-38576343-2013, where 1115 is the OKP code, 017 is the serial number assigned by the developer, 38576343 is the OKPO code, 2013 is the year of approval.
Document structure.
IN Russian Federation the development procedure and general structure of technical conditions are determined by GOST 2.114-95 “Unified system of design documentation”. According to this GOST, as well as other similar standards in force in Russia, the technical specifications must contain an introductory part and sections arranged in the following sequence:
· technical requirements;
· safety requirements;
· security requirements environment;
· acceptance rules;
· control methods;
· transportation and storage;
· operating instructions;
· manufacturer's warranty.
Specifications may be normative document, for compliance with which products are certified and a certificate of conformity is obtained. Also, technical specifications are the main document necessary for decision-making by the authorized services of Rospotrebnadzor during the sanitary and epidemiological assessment of domestic products or Roszdravnadzor when registering medical devices. In some cases, specifications may be subject to registration with Rosstandart, coordination with fire services, technical supervision, etc.
Before installing the magnetic PME starter, it is necessary to clean the device elements from dust that may have appeared during long-term storage or transportation. You should also carefully study the manufacturer's recommendations for installing and operating the device. The PME series magnetic starter may only be installed on a vertical surface with a maximum deviation from the vertical of 5°.
It is also worth carefully inspecting the internal elements of the magnetic starter. So, the core must be free of oil and dust. The presence of contaminants disrupts the operation of the device; during operation, the starter begins to hum strongly, which should serve as a signal for the need to clean the magnetic starter. The manufacturer recommends performing a preventive inspection and cleaning of the housing and internal elements of the starter when stopping the operation of the electric motor at least once a month. The manufacturer's warranty is given for 2 years. But even after this period, the device can be used if its condition complies with the established technical specifications.
Figure 1. Connection diagram of a reversing magnetic starter
The circuit consists similarly, the same as on not reverse circuit, the only thing that was added was a reverse button and a magnetic starter.
The principle of operation of the circuit is a little more complicated, let’s look at it in dynamics. What is required from the circuit is to reverse the motor by reversing two phases. In this case, a blocking is needed that would prevent the second starter from turning on if the first one is in operation and vice versa. If you turn on two starters at the same time, a short circuit will occur - a short circuit on the power contacts of the starter.
We turn on the QF - automatic switch, press the “Start” button, apply voltage to the KM1 starter coil, the starter is triggered. The power contacts turn on the engine, while the start button “Start” is bypassed.
The second starter - KM2 - is blocked by a normally closed KM1 - block contact. When KM1 - the starter is triggered, KM1 - the block contact opens, thereby opening the prepared coil tip of the second KM2 - magnetic starter.
To reverse the engine, it must be turned off. We turn off the engine, press the “C - stop” button, and remove the voltage from the coil that was in operation. The starter and block contacts return to their original position under the action of springs.
The circuit is ready for reverse, press the “Start” button, apply voltage to the coil - KM2, the starter - KM2 is triggered and turns on the engine in the opposite rotation. The “Start” button is shunted by the block contact - KM2, and the normally closed block contact KM2 opens and blocks the readiness of the magnetic starter coil - KM1.
For reliable operation of the circuit, it is necessary that the main contacts of the KM1 contactor open before the closing of the breaking auxiliary contacts in the KM2 contactor circuit occurs. This is achieved by appropriate adjustment of the position of the auxiliary contacts along the armature.
When the thermal relay - “P” is triggered, the normally closed contact “P” opens, and shutdown occurs in the same way.
In serial magnetic starters, double blocking is often used according to the above principles. In addition, reversible magnetic starters can have a mechanical interlock with a changeover lever that prevents the simultaneous operation of the contactor electromagnets. In this case, both contactors must be installed on a common base.
5. MAINTENANCE AND REPAIR
5.1 Maintenance
During the period between repairs, it is carried out Maintenance electrical devices, which is a set of operations or an operation to maintain the functionality or serviceability of the device when used for its intended purpose, waiting, storage and transportation. The device is not disassembled.
The typical scope of maintenance work for magnetic starters includes: cleaning from dirt and dirt, lubricating rubbing parts, eliminating visible damage, tightening fasteners, cleaning contacts from dirt and deposits, checking the serviceability of casings, shells, housings, checking the operation of signaling and grounding devices .
It is recommended to check and adjust thermal relays in the laboratory using special electrical devices. Checking the relay begins with an external inspection: checking the presence of seals, the integrity of the casing and its tight fit to the base, the condition of the seals, and cleaning the relay.
After removing the casing, they begin an internal inspection: clean the parts, check the tightness of screws, nuts, fastening springs, contacts, bearings, magnetic circuits; check the reliability of internal connections; adjust the mechanical part of the relay; the contacts are thoroughly cleaned and polished with blued material (needles or abrasive materials should not be used).
Next, measure the insulation resistance with a 1000 V megohmmeter between the electrical parts of the relay and the housing, which must be at least 10 MOhm, and check the settings. If defects are found that are beyond the ability to eliminate them in the laboratory, the relay is replaced with a new one.
5.2 Repair work
As a result of operation, accidents, overloads and natural wear and tear, some electrical equipment and networks fail and must be repaired.
Repair is a set of operations to restore the serviceability or performance of electrical devices, restore their resources or their components. A repair operation is understood as a completed part of a repair performed at one workplace by performers of a certain specialty, for example: cleaning, disassembling, welding, making windings, etc.
There are several repair methods: repair by the operating organization, specialized repair, repair by the manufacturer of the product.
The last two methods have significant advantages that make it possible to achieve high technical and economic indicators through the use of non-standardized, highly productive, efficient equipment, production of spare parts, implementation modern technology, close to the technology of electrical machine-building plants, using new materials.
These methods make it possible to create an exchange fund from new or repaired electrical machines and other equipment of common series and types. But these methods exclude the possibility of prompt repair of critical and non-standard equipment, equipment manufactured by foreign companies, and equipment of old brands. In addition, the problem of maintenance, which accounts for more than 80% of the labor intensity of repairing electrical networks and large-sized equipment (transformer substations, switchgears, control panels, etc.), has not been solved. Reliability, uninterrupted operation and safety of electrical equipment and networks can be ensured the right system repair of electrical equipment by the operating organization. Such a system is planned preventive maintenance (PPRM), which is a form of organizing repairs, consisting of a set of organizational and technical measures that ensure the implementation of maintenance and preventive repairs.
In electrical devices, moving, fixed and arcing contacts are most often damaged. Repair mainly consists of identifying the malfunction, eliminating it, replacing damaged and worn parts, followed by adjustment and testing. During operation, the contacts are cleaned of metal deposits, soot, and oxides. Clean with a file with a fine (fine) notch. Eliminates strong and weak contact pressure. To do this, place paper (foil) between the contacts, pulling the movable contacts through a dynamometer and pulling out the foil. Normal force is 0.5-0.7 kg. The magnetic contact system can create noise, humming, the reasons for this are: the armature does not fit tightly to the core, damage to the short-circuited turn, very high contact tension, the armature is skewed in relation to the core, there is rust in places where the armature and core touch, magnetic starters and contactors should not be allowed different times of closing power contacts. Short-circuited turns for contactors and magnetic starters are made of copper, brass and aluminum. They fit into stamped grooves at the ends of the core. Attention is drawn to arc chutes. Their absence can cause the arc to overlap individual phases. Coils are repaired in case of frame damage, breaks, turn short circuits and complete combustion. A break in the coil is detected if no traction force is developed and no current is consumed. A turn fault is detected by abnormal heating and decreased thrust.
Figure 2 - Magnetic starter contactor: 1 - base; 2 - block contacts (auxiliary contacts); 3 - anchor axis; 4 - shock-absorbing springs; 5 - core; 6 - coil; 7 - anchor; 8 - emphasis; 9 - isolation chamber; 10 - fixed contact; 11 - moving contact; 12 - armature return spring
For contactors, main contacts, flexible connections, arc chutes, coils, springs, and short-circuited turns are often replaced. The insulation resistance of the windings should not exceed 0.5 MOhm. The heating elements of the relay burn out more often. Nichrome and fechral are used for heating elements. Individual heating elements are made by stamping. Spiral heating elements are cadmium coated to protect against oxidation. Figure 6 shows the magnetic starter contactor.
Contact repair. Contamination, wear, burning, soot or oxidation, deposits and splashes of metal on the surface of moving (including switch knives) or fixed (knife jaws) contacts, as well as on plates and contact bridges, are eliminated with a cotton napkin soaked in gasoline or a file. When the thickness of the contacts is less than 50% of the original value, the burnt contacts are replaced with new ones. Contacts that have a metal-ceramic (silver-nickel) or other coating that provides increased conductivity or corrosion resistance are not allowed to be cleaned with a file or needle file! Contacts are cleaned with a cotton cloth soaked in gasoline, and especially critical contacts (6-10 kV switches, relays) with alcohol. Use a finely cut file, needle file or glass sandpaper to clean or remove deposits and deposits of metal on uncoated contacts. The contact surface must be clean; cavities with an area of no more than 1 mm2 and a depth of up to 0.2 mm are allowed. The thickness of the jaws and knife switches should not be less than 80% of the original.
If the contact springs are broken or weakened, or the anti-corrosion coating is damaged, the springs are replaced.
Repair of electromagnet coils. Reels can be framed or frameless. The most common damage is cracks up to 15 mm long in the frame. They are eliminated as follows. The surface of the frame around the crack is cleaned of dust and oil with a cotton cloth soaked in gasoline. A layer of BF glue is applied to the surface of the crack and dried in air for 10-15 minutes, then a second layer is applied and left for another 5-10 minutes. After this, the glued parts of the frame are tightened with taffeta or cotton insulating tape and dried in an oven for 1.5-2 hours at a temperature of 100-110 ° C, after which they are cooled and the bandage is removed.
If the insulation resistance is reduced (less than 0.5 MOhm), the coil is placed in a drying cabinet with a temperature of 60-70 ° C for several hours. After this, the insulation resistance is checked and, if the standard is reached (at least 1 MOhm), it is immediately impregnated with one of the BT-988 or BT-987-M varnishes and dried a second time for 8 hours at a temperature of 105 °C.
If the outer layer of the coil insulation is damaged or the winding wire breaks in the upper layers of the winding, remove the outer insulation of the winding and the damaged turns to the point of damage or breakage, solder, insulate the soldering area of the new winding wire and wind the required number of turns, repeating the operations that are performed when winding new coils .
In case of significant damage to the frame, interturn short circuits, or burning of the winding insulation to a great depth, the coil must be replaced with a new one.
Repair of frame reels. Select the frame and wire required for the coil, the parameters of which must correspond to the passport data. The ends of the coil wire are cleaned with sandpaper, tinned and soldered with POS-30 solder to the output conductor. The terminal consists of a sheet or brass part with a conductor of a larger cross-section than the winding wire soldered to it to ensure the mechanical strength of the terminal. The soldering area is insulated.
Before installation on the winding machine, the frame should be wrapped in a double layer of electrical insulating paper with a thickness of 0.02-0.03 mm and the end should be glued to the frame. When winding, you must ensure that the tension on the wire is not excessive, as this may cause the wire to break. When winding, the wire should lie in an even, dense layer. Between the 1st and 2nd layers of the winding, interlayer insulation made of insulating paper is laid. If the coil is heat-resistant, then thin fiberglass fabric is used for interlayer insulation.
The winding terminals can be soft or hard. Soft ones are made from flexible mounting wires. The place where the soft lead is soldered to the winding is insulated with a polyvinyl chloride tube, on which a strip of varnished cloth is applied.
Figure 3 - Split mandrel (a) and frameless coil (b): 1 - part, 2.5 - cheeks, 3 - sleeve, 4 - pin, 6 - nut, 7 - pin, 8 - slot, 9 - output, 10 - bandage
Rigid leads, as indicated above, are made from pre-tinned brass strips. They are isolated from the winding by gaskets. The leads soldered to the coil are secured with threads. The soldering points are wrapped with an insulating gasket that has a cutout for the vertical part of the terminal.
Repair of frameless reels. A split mandrel is made according to the dimensions of the defective coil (Figure 7, a). Its size, taking into account the insulation of the coil, must correspond to the core for which the coil is intended. The mandrel is installed on a lathe and secured to part 1 or on a special winding device. A taffeta tape is placed on the mandrel in four places around the perimeter in such a way that after winding the coil it is enough to install bandage 10 (Figure 7, b). Using taffeta tape, the mandrel sleeve is wrapped in two layers of electrical cardboard with a thickness of 0.2-0.3 mm and a width equal to the height of the coil. To the beginning of the winding, solder a piece of flexible copper wire with POS-30 solder (pin 9). The soldering area is insulated with a micanite strip.
When winding a coil, each layer is covered with impregnating varnish and thin electrical paper 5-7 mm wide than the height of the coil. These edges of the paper are wrapped under the outermost turns of the next layer of the coil.
A piece of flexible wire is also soldered to the end of the winding for output. The coil is banded with previously laid taffeta tape. The manufactured coils are dried for 2 hours in an oven at a temperature of 80-90 ° C, the insulation resistance and integrity of the winding are checked. Immediately after drying, while still warm, the coil is dipped into an impregnation bath with ML-92 varnish and held until the emission of bubbles stops, after which it is dried again for 4-5 hours at a temperature of 100-110 ° C. The dried winding of the coil is wrapped with two or three layers of insulating paper, two layers of varnished fabric or taffeta tape, the terminals and frame are cleaned of the varnish layer, and a tag is stuck on.
The insulation of a coil ready for use is tested with an alternating current voltage of 2000 V with a frequency of 50 Hz for 1 minute, gradually increasing the voltage. The insulation resistance of the coil after testing should not be less than 0.5 MOhm.
Repair of magnetic circuit. Contaminants are removed with a cotton cloth soaked in gasoline; traces of corrosion are thoroughly cleaned with a steel brush and sandpaper; hardening on the contact surfaces of the core and yoke is removed by grinding the surface with a file on a grinding machine.
The area of contact between the core and the yoke is checked as follows: take sheets of white and carbon paper folded together, compress the yoke and the core with a certain force, and get an imprint of the contact area on the paper, which must be at least 70% of the area of the core. The tightness of the fit is checked with a 0.05 mm feeler gauge. The probe should not enter the space between the yoke and the core more than 5 mm. Places of unevenness are scraped along the steel sheets.
The damaged short-circuited turn is replaced with a new one, made to the size of the defective one from the same material. The damaged coil is sawn and removed. The coil grooves are cleaned with a file and the coil is secured in the grooves.
The reduced value (less than 0.2 mm) of the non-magnetic (air) gap between the middle cores of the core and the yoke of the magnetic circuit is brought to the norm of 0.2-0.25 mm by filing the middle core of the yoke (or core), which is checked with a probe. Non-parallelism of planes is allowed within 0.01 mm.
The cleaned core and yoke are immersed in a bath of GF-92-ХС enamel so that their contact surfaces are not varnished. Painted parts are air dried.
6. TOOLS AND DEVICES
1. Set of screwdrivers;
2. A set of keys;
3. Split mandrel;
4. Frameless reel;
5. Sanding paper;
6. Bakelite varnish or BF-2 glue;
7. 5% solution of soda ash in water;
8. Varnished fabric;
9. Taffeta ribbon;
10. Wiping material;
11. White spirit or gasoline.
7. ORGANIZATION OF WORK
7.1 Requirements for operating personnel
Persons over 18 years of age who have special education and have undergone training to the extent required for the position are allowed to work at electric power facilities.
With the head of the structural unit:
a) introductory and targeted briefing on labor safety;
b) testing knowledge of rules, labor protection standards (safety rules), technical operation rules, fire safety;
c) continuous professional development.
With operational managers, operational and maintenance personnel:
a) introductory, primary at the workplace, repeated, unscheduled and targeted briefings on labor safety, as well as fire safety briefings;
b) training for a new position or profession with on-the-job training (internship);
c) testing knowledge of rules, labor protection standards, technical operation rules, fire safety and other government norms and regulations;
d) duplication;
e) special training;
f) control emergency and fire drills;
g) continuous professional development.
The head of the organization, in accordance with the law, must not allow employees to perform job duties who have not undergone training, instruction, internship, testing of knowledge of labor protection, mandatory medical examinations, as well as in the case of medical contraindications.
Workers hired to perform work in electrical installations must have professional training appropriate to the nature of the work. In the absence of professional training, such workers must be trained (before admission to independent work) in specialized personnel training centers (training centers, educational and training centers).
An employee who has passed a knowledge test on labor protection during the operation of electrical installations is issued a certificate in the established form, in which the results of the knowledge test are entered. For operational managers and managers of operational and repair personnel, the frequency of testing knowledge of labor safety rules and regulations should be at least once a year.
Periodic testing of knowledge of rules and regulations on labor protection (safety rules) of workers of all categories must be carried out at least once a year.
The following are subject to verification:
a) operating rules, intersectoral labor protection rules, fire safety rules for energy enterprises;
b) job and production instructions, emergency response plans (instructions), emergency modes;
c) the design and principles of operation of technical safety equipment, emergency protection equipment;
d) the design and principles of operation of equipment, instrumentation and controls;
d) technological schemes and energy production processes;
f) safety conditions for the operation of power plants;
a) use protective equipment and provide first aid to victims of an accident;
b) power plant control (using simulators and other technical training aids).
Operating personnel servicing electric energy meters, current and voltage measuring transformers must have diagrams and instructions on the permissible operating modes of electrical equipment in normal and emergency modes, as well as requirements for servicing this equipment, presented in the local operating instructions for electric energy meters, measuring transformers current and voltage.
Personnel with special education and training in accordance with the requirements for the position must be allowed to work on operation and maintenance. Work with personnel must be carried out according to plans approved by the management of the power facility and structural unit.
The functions of the duty personnel of electric power facilities should include:
Periodic inspections, monitoring the performance and condition of technical equipment - electricity meters in accordance with the operating instructions;
Monitoring the presence and condition of meter seals and test boxes;
Maintaining records of the state of the system's technical equipment in the operational log and trouble log;
Ensuring safe maintenance and repair of technical equipment in electrical installations of the facility.
The facility's duty personnel must know methods for visually diagnosing the condition of technical equipment installed on panels and in metering cabinets.
For the operation and maintenance of facilities, depending on local conditions, maintenance units (services, departments, bureaus or teams) should be formed. As a rule, they should include:
Administrator;
Operators or dispatchers;
Repair teams, including mobile ones.
8. SAFETY PRECAUTIONS
Electrical installations and devices must be in full working order, for which they must be periodically checked in accordance with the operating rules. Non-conductive parts that may become live as a result of insulation breakdown must be reliably grounded.
It is prohibited to carry out work or tests on live electrical equipment and equipment in the absence or malfunction of protective equipment, blocking fences or grounding circuits. For local portable lighting, special lamps with 12 V lamps must be used. The use of faulty or untested power tools (electric drills, soldering irons, welding and other transformers) is prohibited. In rooms with an increased risk of electric shock (damp, with conductive floors, dusty), work must be performed with special precautions. Great importance is attached to protective equipment.
Disabling live parts. Turn off equipment that requires repair, and those live parts that can be accidentally touched or approached at a dangerous distance. The disconnected section must have visible breaks on each side of the live parts to which voltage can be applied. Visible breaks are caused by disconnected disconnectors, load switches, circuit breakers, removed fuses, disconnected jumpers or parts of the busbar.
When disconnecting the voltage, safety measures must be taken (for example, fuses are removed using insulated pliers while wearing dielectric gloves and safety glasses).
Hanging prohibiting posters and fencing live parts that are not disconnected. Posters are hung on disconnected switching devices: “Do not turn on - people are working!”, “Do not turn on - work on the line!”, “Do not open - people are working!” (on air supply valve drives); If necessary, fences are installed on live parts that are not disconnected.
Checking for no voltage. First, the permanent barriers are removed. Connect portable grounding to a metal bus connected to a grounding device. The voltage indicator is used to check the absence of voltage, but before doing this, it is necessary to check its serviceability by bringing the probe (contact-electrode) closer to the live part at a distance sufficient for the lamp (LED) to glow. If it starts to glow, it means the pointer is working.
Using a working indicator, check the absence of voltage between phases, between each phase and the ground, between phases and the neutral wire. If the indicator shows voltage on the live part, it is necessary to replace the removed fences and find the cause of the voltage. It is impossible to draw a conclusion about the absence of voltage at the installation based on the readings of the signal lamps and voltmeter, since they are only additional means of control.
Applying and removing grounding. After checking that there is no voltage, the disconnected parts are immediately grounded using a portable ground, one end of which has already been connected to a grounding device. In this case, portable grounding clamps are applied to the disconnected current-carrying parts, first using an insulating rod, and then these clamps are secured with a rod or manually. Remove grounding (after completion of work) in reverse order: first from live parts, and then from the grounding bus using an insulating rod. All work is performed with dielectric gloves.
Fencing the workplace and posting safety posters.
Along the path from the entrance to the electrical installation to the place of repair work, temporary fences or portable shields are installed, on which (as well as on the permanent fences of neighboring cells) warning posters (“Stop - voltage”) are hung, and at the work site - instructive posters (“Work here” , “Get in here”).
Work in electrical installations must be carried out by trained personnel with electrical safety qualification groups (I-V), and technical activities must be carried out by operational personnel (one of them must have a qualification group of at least IV).
Organizational measures during the preparation of the workplace and during the period of repair work include: drawing up a work permit (work order) or order; permission to work; supervision during work; recording in a journal entries about breaks in work, transitions to another workplace, and the end of work.
Permission work order (work order) is an order drawn up on a special form for the safe performance of work, defining its content, place, start and end times, necessary safety measures, composition of the team and persons responsible for the safe performance of work.
Workers are responsible for their compliance with safety rules and instructions received upon admission to work and during work.
LIST OF LITERATURE
1. Rules for the construction of electrical installations (PUE). 7th ed. - M.: Publishing House NC ENAS, 2003.
2. Rules for the operation of consumer electrical installations. Energy service. - M., 2003. (PTEE)
3. Akimova N.A., Kotelenets N.F., Sentyurikhin N.I. Installation, technical operation and repair of electrical and electromechanical equipment. - M.: Publishing house “Masterstvo”, 2002.
4. Atabekov V.B. Installation of electrical networks and power electrical equipment. - M.: Higher School, 2007. Zhivov M.S. Installation of lighting electrical installations. - M.: Higher School, 2007.
5. Zhivov M.S. Electrician installing switchgear for industrial enterprises. - M.: Higher School, 2007.
6. Kisarimov R.A. Electrical equipment repair. - M.: Radio Soft, 2005.
7. Sibikin Yu.D., Sibikin M.Yu. Maintenance and repair of electrical equipment and networks of industrial enterprises. - M.: Academy, 2003.
Posted on Allbest.ur
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V. A. Smirnov, K. V. Panov
EDUCATIONAL MANUAL
for PERFORMING laboratory WORK
WHEN STUDYING A DISCIPLINE
"Production and REPAIR OF ROLLING STOCK"
Part 2
UDC629.4.083: 629.488
Educational and methodological manual for performing laboratory work when studying the discipline “Production and repair of rolling stock.” Part 2 / V. A. Smirnov, K. V. Panov. Omsk State University of Communications. Omsk, 2016. 31 p.
Developed in accordance with the discipline program “Production and repair of rolling stock”. Contains basic information about technological processes for repairing components and assemblies of electric rolling stock. The educational manual consists of two parts. The second part includes four laboratory works devoted to the study of technological processes for revising electrical devices.
Intended for fourth year students of the specialty "Rolling Stock" railways» specializations “Electric railway transport” and “High-speed ground transport” full-time and part-time courses. The educational and methodological manual can be used to train students in blue-collar professions and during training courses for railway transport workers.
Bibliography: 4 titles. Rice. 4.
Reviewers: Dr. Tech. Sciences, Professor V.A. Kruczek;
Ph.D. tech. Sciences, Associate Professor O. V. Balagin.
___________________________
© Omsk State. university
Railways, 2016
Introduction. 5
Laboratory work 5. Inspection of individual contactors. 6
5.1. General information. 6
5.2 Work order.. 10
5.3 Used measuring tools and devices. eleven
5.5. Test questions.. 11
Laboratory work 6. Revision of a group switch. 12
6.1 General information. 12
6.2 Work order.. 15
6.3 Used measuring instruments and devices. 16
6.5. Test questions.. 17
Laboratory work 7. Inspection of a high-speed switch. 17
7.1 General information. 17
7.2. Work order... 22
7.3. Used measuring instruments and devices. 23
7.5. Test questions.. 24
Laboratory work 8. Inspection of the pantograph. 24
8.1 General information. 24
8.2. Work order... 27
8.3. Used measuring instruments and devices. 28
8.5. Test questions.. 28
Bibliographic list. thirty
INTRODUCTION
During the operation of electric rolling stock (EPS), wear of the rubbing surfaces of parts, aging of insulation, the appearance of fatigue cracks, and disruption of the adjustment of components occur.
The entire process of repairing a part, assembly, piece of equipment or an electric locomotive as a whole is conventionally divided into four independent technological processes: cleaning, defect detection, repair and testing (acceptance), performed in specialized positions. These works form the basis of the technological process of repairing any electric locomotive bridle.
Laboratory work is intended for students to more deeply study repair technological processes, as well as acquire practical skills in identifying defects, adjusting and testing individual components and assemblies of EPS.
The second part is devoted to the study of technological processes for revising electrical devices: individual contactors, group switches, high-speed switches and pantographs.
Students prepare for laboratory work in advance, independently, using the literary sources indicated in the guidelines. The student is allowed to perform the next work only after an interview with the teacher, as well as if there is a report on the previous work.
During laboratory work, the student uses literary sources, repair manuals and instructions from JSC Russian Railways, posters, measuring instruments, tolerance control tools and devices recommended by guidelines. Work is carried out by teams of no more than four people.
Each student completes reports on all work individually in a special notebook. The preparation of reports must comply with the requirements of the guidelines, as well as the approved standards of the enterprise (university).
Particular attention should be paid to compliance with safety rules, instructions on which are given by the teacher before the start of each laboratory work.
Laboratory work No. 5
REVISION OF INDIVIDUAL CONTACTORS
Purpose of the work: to gain practical skills in checking parameters, assessing performance and identifying defects of individual electropneumatic and electromagnetic contactors. Familiarize yourself with the technology for inspecting individual contactors and methods for eliminating defects.
General information
Inspection, revision and repair of individual contactors are carried out in accordance with the requirements of the Electric Locomotive Repair Manuals.
Individual contactors are subject to inspection and revision at TP-1 and TP-2. At the same time, the arc-extinguishing chambers are removed from the contactors and sent to the workshop for more thorough cleaning of carbon deposits and blowing with compressed air. The contactors themselves are inspected and repaired directly on the electric locomotive. Repairs involving disassembly of contactors are carried out using TR-3 with removal from the EPS.
When performing laboratory work, operations are provided in the scope provided for by the technological process of inspecting individual contactors during routine repairs of TR-1.
On an electric locomotive, they check by ear the clear operation of all devices when switched on from the control cabin, and control the operation of electrical circuits. Pay attention to the proper operation of the pneumatic drive. It is advisable to carry out such a check together: one mechanic controls the devices from the remote control in the driver’s cabin, and the other, being in the high-voltage chamber, carefully monitors the switching on and off of the devices and makes sure that there are no air leaks from the pneumatic system.
Usually, based on the first check, it is possible to draw a conclusion about the condition of the device and even establish the cause of the damage. For example, an electro-pneumatic contactor turns on clearly, but turns off slowly. This may be due to a jammed moving system, damage to the trip spring, or loosening of its fastening.
After checking the functioning, the arc chutes are removed, the dimensions and wear of the parts are checked for compliance with existing tolerance standards, cleaned of dust and carbon deposits, and blown with compressed air at a pressure of 300-350 kPa (3-3.5 kgf/cm2).
Feeler gauges are used to measure the gaps in the hinges, and also measure the diameters of the rollers, axles, bushings and holes. Rollers and axles whose dimensions are equal to the maximum values are replaced. The normal operation of the devices can be disrupted not only as a result of large wear in the hinges, but also due to the formation of scoring in them or lack of lubrication. There are frequent cases of welding of hinges as a result of the flow of short circuit currents, breakage or loosening of copper shunts. To identify possible jams, the operation of the moving systems of the devices is checked by lightly moving them by hand.
Be sure to make sure that all free rotation axes are pinned or secured from falling out in some other way. When changing components and parts, it should be remembered that bolted connections must have spring washers or, in accordance with the drawings, must be secured in another way to prevent the bolts and nuts from being unscrewed.
The condition and fastening of power and low-voltage wires is checked. Wire tips with a break of more than 20% of the wires, with loose soldering, cracks or a contact surface reduced by more than 1/3 must be replaced and re-soldered.
The condition of the insulation of wires, coils of electromagnetic valves, including electromagnets, and the surface of insulating posts is checked. They may have both electrical and mechanical damage. Damaged glaze of porcelain insulators, damage to the crimping surface of contactor stands are usually washed from soot and dirt with napkins soaked in gasoline, cleaned with glass cloth and coated with NTs-925 varnish or GF-92HK enamel.
An electric arc, when there is a disruption in the arc extinguishing process or a short circuit, often burns and chars the insulation of arc extinguishing coils and racks to a layer of mica and even to metal. If only the outer layer of insulation is damaged, the burnt area is cleaned with a glass cloth, then thoroughly washed with gasoline and covered with enamel.
An important condition for maintaining the functionality of electrical devices is the regular addition of lubricant to the friction unit. If necessary, lubricant is added to the hinges of the moving parts of devices where friction of steel on steel or on brass occurs.
External inspection and measurements of wear, tear and contact pressure values check the technical condition of the moving and fixed contacts. When starting to clean contacts, especially power ones, they evaluate the color, size of the melting and the nature of the spread of frozen copper splashes over the surface of the contacts. The main reason for the deterioration of the contacts is a decrease in their pressure. It occurs not only from incorrect adjustment of the device, jamming of its moving parts, but also in the event of damage or misadjustment of the lapping, turning on or off spring. The spring may also lose its elastic properties due to excessive heating when the fastening is loosened or the copper shunt bridging it is broken, the electric arc is transferred, or the contacts of the device become unacceptablely heated. The consequences of reducing contact pressure are significantly aggravated by the dynamic effects of the body, leading to “rattling” of the contacts of the switched on device.
Another reason for excessive heating may be improper mating of the contact surfaces, which leads to burnout of the metal at the point of contact and the formation of a spot with a rough surface. Subsequently, these burns cause darkening of the entire contact and its melting. Repair manuals state that the length of the contact line must be at least 80% of the contact width. To test the touch, carbon paper and thin (tissue) paper are used. Retracting the movable contact with your hand, place carbon paper and blank paper between the contacts, and use your son-in-law to lower the movable contact. The touch line is clearly imprinted when the contacts collide. The lateral displacement of the contacts should not exceed 1 mm.
The contact pressure is checked with a spring dynamometer. Considering that the springs pressing the contacts have significant rigidity, the pressure is controlled directly at the moment of separation of one contact from the other. To do this, a thin strip of paper is clamped between the contacts (Fig. 5.1, a). Then, hooking the dynamometer to the movable contact, pull it strictly along the shutdown line, while simultaneously applying force to the strip of paper. To eliminate errors in measuring contact pressure, the attachment point of the dynamometer must be chosen so that the line of application of force to the dynamometer passes through the point of contact of the contacts.
Rice. 5.1. Checking the controlled parameters of the contactor
Important factors that determine the stable operation of movable contact connections are solution (rupture or opening), rubbing and failure of contacts. The solution is the shortest distance A between the contacts of a completely switched off contactor (Fig. 5.1, b). For most devices, it is convenient to measure the contact opening with a caliper, but it is more advisable to use pass-through and non-pass-through templates.
The rubbing of the contacts is checked when the contactor is turned on manually by directly observing the rolling of the contacts. In this case, the moving contact lever must have some free play after the contacts come into contact. It is also necessary to keep in mind that good lapping is ensured by the geometric dimensions of the moving contact parts, the engaging and lapping springs, and the shape of the contacts. For contactors it also depends on the failure of the moving contact.
By failure we mean the distance that the moving contact could travel if the fixed contact was removed from a fully switched device. However, in reality it is not possible to measure this distance. Therefore, failure is determined indirectly by the gap between the contact holder and the lever (Fig. 5.1, c).
Work order
1. Study the procedure and content of inspection and revision of individual electromagnetic and electro-pneumatic contactors of an electric locomotive, become familiar with possible malfunctions and methods for eliminating them
2. Inspect and audit the individual contactor as directed by the teacher. At the same time, by inspection, evaluate the technical condition of contacts, arc extinguishing devices, brackets, racks, pneumatic and electromagnetic drives of individual contactors.
3. When inspecting contactors, check the condition of the flexible shunts of the arc extinguishing coils, their fastening, measure the thickness, gap, pressing, failure, lateral displacement of the contacts and the line of their contact. Check the operation of contactors at the minimum permissible values of compressed air pressure and voltage of the electrical control circuit of the electric locomotive, measure the contact pressure values. Enter the results of inspection and measurements in the table. 5.1.
Based on a comparison of the actual values of the monitored parameters with the acceptable ones, make a conclusion about the (un) suitability of individual contactors for operation, as well as the need to replace individual components and parts or carry out repair work to eliminate detected defects.
Table 5.1
Contactor inspection and measurement results