Detailed Explanation of Three-phase AC Motor Winding Technology

Wiring Technology of Three-phase AC Motor Windings

After all the coils of the winding are embedded in the core slots, the three-phase winding can be connected according to the prescribed connection method. The specific wiring steps are as follows:

(1) Preparation before wiring Before wiring, you should prepare materials and tools such as glass fiber insulation sleeve, glass fiber varnished cloth tape, wax wire, rosin, solder, lead cable, hammer, scissors, wire cutters, wire management board, elastic scraper and soldering iron.

(2) Inspection before wiring: Based on the records of the original technical data, check the relative positions of the three-phase winding output terminals, the number of parallel branches, the connection method, the output direction, etc. Check whether the coils of each phase winding are reversely inserted, connected incorrectly, or the insulation pads between the phases are incorrect. If any errors are found, they should be corrected immediately.

(3) When connecting the windings, the outlet ends of each winding should be arranged first, and the position of the lead-out end should be reasonably selected. Generally, the outlet position is selected on both sides of the end of the winding near the outlet box. The connection can be carried out phase by phase in the order of A, B, and C three-phase windings. The connection method of each phase winding can be connected in accordance with the salient pole or common pole connection method. When connecting, put glass fiber paint sleeves on the two wire ends that need to be connected. The length of the sleeve should extend into the coil nose about 20mm. Then use the elastic scraper shown in Figure 5-44 to scrape off the insulation layer of the wire. The two wire ends can be connected by parallel twisting. Then use an electric soldering iron or solder and rosin to weld the tip twisted part. After welding, the electric soldering iron should be moved away from the welding part to avoid leaving the solder tip there and piercing the insulation. Then use an insulating sleeve or insulating varnished cloth tape to wrap it in two layers to carefully insulate the welding part of the connecting wire.

(4) Welding of lead cable: Measure the length of lead cable according to the outlet position and cut it, and strip off the insulation layer at the lead cable connection point, connect it with the winding lead wire end with the paint layer scraped off, and weld it carefully and firmly after the wire end is connected. Then wrap the lead cable connection point with varnished cloth tape, and put a glass fiber varnished sleeve of appropriate size on the outside of the wrapped insulating varnished cloth tape.

(5) Binding of winding ends First, use a hammer and a wire-straightening plate to trim the horn U at the winding end, so that the horn mouth is round and meets the size requirements. The connecting wires and cables should be arranged flatly at the winding end and tied firmly with wax wire.

Wire Embedding Technology for Three-phase AC Motor Windings

The insertion of the three-phase AC motor random coil is a relatively delicate work, which requires the wound three-phase winding to be inserted into the core slots one by one according to the specified pitch and connection method. The specific steps of the random coil insertion are as follows:

1) Carefully check and clean the residue in the core slot, use files and screwdrivers to correct the protruding silicon steel sheets and burrs, correct the bending of the silicon steel sheets at both ends of the core caused by the removal of the old winding, and use a hair dryer or leather tiger to blow away the debris in the slot.

2) Prepare slot insulation, phase insulation, slot wedges, three-phase windings of the entire motor, hammers, scissors, wire crimping plates, wire management plates and other materials and tools, and place the slot insulation into the slot one by one.

3) Carefully check the original technical data of the motor repair to clearly understand the winding form, pitch, number of parallel branches and connection method, and select a reasonable wire embedding starting position and winding embedding sequence based on the above data.

4) When starting to embed the wire, flatten the first coil to be embedded with your fingers near the component in front of your chest, so that all the turns are flat in a row, and then obliquely embed part or all of the turns of the coil from the slot at one end. When many turns are blocked in the slot, gently shake the coil with your fingers to slowly embed the turns into the slot, or use a wire management board to sort out the turns and embed them neatly into the slot.

5) Push the other side of the first coil to be embedded through the pitch slot and do not embed it in the slot for the time being, and use both hands to gently press the bell mouth on both sides of the coil. If it is a single-layer chain type, single-layer cross type and double-layer stacked winding, the other side of the coil can only be embedded in its pitch slot when the number of coil side embedded in the slot reaches the number of slots of the coil pitch.

6) When inserting the second coil and subsequent coils of the starting pole phase group, the connecting wires between the coils should be arranged before inserting them into the slot. Then, the coil elements are twisted and flattened once and pulled into the slot. The connecting wires should be placed on the inside of the coil, because this will make the winding neat and beautiful after insertion.

7) After the first pole phase group of phase A is embedded, the interlayer insulation is inserted, and the interlayer insulation is flattened and compacted with a hammer and a wire pressing plate. Then, the first pole phase winding of phase B is embedded in the same way and the interlayer insulation is padded, and then the first pole phase group of phase C is embedded. When the coil in the pole phase group reaches the number of pitch slots, the other element side of the coil should be embedded in the upper layer of the pitch slot. After the coil is embedded in the slot, the excess insulation paper outside the slot can be cut off, and the insulation paper can be folded and pressed into the slot with a wire arranging plate and compacted with a wire pressing plate, and then the slot wedge is driven in. However, special attention should be paid to avoid damaging the slot insulation and electromagnetic wire when driving the slot wedge. Then, the coils that reach the number of pitches in the first pole phase group of phase C are embedded in the same way. Then, the second phase group of phase A is embedded. After the coil is embedded, the slot wedge is driven in, the interlayer insulation is padded, the interphase insulation at the rear end is separated, and the leads of the pole phase group are arranged.

8) When embedding into the first pitch, it is best to leave the coil component edges that have not been embedded yet (commonly known as "hanging handle" coils). At this time, these coils should be turned up one by one and tied up with yarn tape. The turning height should be based on not affecting the embedding of the last coil component edge. After the lower layer component edges are embedded, the "hanging handle" coil component edges are put down and embedded in the slots in sequence.

9) After all the coils of the winding are embedded in the core slots, you can use a hammer and a wire management plate to tap the end of the winding lightly to make the end of the winding a rounded bell mouth that is lower than the inner diameter of the stator core.

10) Trim the insulation paper at the end of the winding so that it is 2-3mm higher than the coil surface.

11) If the insulating paper at the bottom of the slot is found to be broken or too loose during the wiring process, it is necessary to pad it with the same insulating material to repair and fill it.

12) If the ends of the coils and connecting wires are messy or severely crossed, they need to be straightened and organized with a wire management board.

Cutting Technology of Three-phase AC Motor Windings

The slot insulation, phase insulation and interlayer insulation of the three-phase AC motor winding random-wound coil generally use 6520 polyester film green shell paper composite foil (commonly known as DMD) for E-level insulation.

The slot insulation is used to pad the core slot, and both sides of it need to be higher than the slot opening so that the coil can be embedded without damage, as shown in Figure 542. In order to ensure the reliable dielectric strength of the winding, the slot insulation should also extend a certain length from both ends of the core. The length of the slot insulation extending from the core should vary depending on the power of the motor. The length of the slot insulation extending from the motor with high power can be slightly longer. Figure 5-43 shows the general slot insulation structure of a three-phase AC motor.