Electric motors are a necessary thing in any household and industry. They perform many functions by moving the substance being transported by means of mechanical devices.
These machines are synchronous and asynchronous, as well as DC. Asynchronous motors are widely used in everyday life. In such motors, the rotation speed does not change with increasing load. That is why such models are most often used.
1 Types of electric motors and repair features
- 1.1 Motor disassembly
2 Rewind motor windings
- 2.1 Features rewind electric motor do it yourself
3 Motor assembly
- 3.1 Rewind specialists recommendations
Types of electric motors and repair features
These devices are made in different designs. The failure of the winding in the industry is repaired by sending the engine to the repair shop, where the engines disassemble, clean, inspect.
Then the rewinding windings are trying to rewind on special winding installations. After that, the engines are assembled and tested at operating speeds with a measurement of the no-load current and under the expected load.
Electric motors are divided into two types:
- with a short-circuited rotor, the motors are easy to manufacture, cheap, and have a high coefficient of usefulness;
- with a phase rotor, use such a constructive solution with insufficient supply voltage, if this power is not enough to start the device.
The malfunction of such devices in everyday life is eliminated together with the service department or handing over this motor to the workshop. But, what to do if there is no service nearby and there is no opportunity to give in for repair to professionals?
The only option to try to make out at home and provide rewind independent forces. Rewind winding can man possessing minimal knowledge about how to rewind.
Before disassembling, it is necessary to treat the motor with wet cleaning, then clean it with a rag. Turn off the fan cover, remove all bolts in sequence. After this, we press the fan, after unscrewing its fixing bolt.
Turn off the mounting stand and fastening flanges. Disconnect boro electric motor with terminal block. All fasteners and bolts must be folded separately so that there will be no problems later on with the assembly. Turn off the front flange with the rotor and pull out.
The different arrangement of electric motors makes one wonder beforehand: “Which of the windings failed the rotor or stator”. Using instruments ohmmeter and megohmmeter we carry out an inspection of the windings.
Call the engine with an ohmmeter between the three phase terminals for the same resistance. We check with ohmmeter each phase to earth, the resistance should be of the order of several megohms and above. Then we take the megohmmeter and check the insulation resistance each winding on the case.
Determined with a faulty winding, in our case stator winding faultyand the rotor has a non-collapsible design. Removing the stator is not an easy task, as it would seem at first glance.
If the winding has melted very strongly and the electric motor has failed due to overheating, then it will not be necessary to beat it out. easy enough to be removed from their attachment points. It so happened that the winding burned a little or it was in a cliff, then the varnish would be very good to hold, and even attempts to knock down with a chisel will not lead to the complete removal of old parts.
Alternatively, you can make a fire and heat the stator housing to all the varnish inside burned out. After such actions, the old deposits will pour out.
It is necessary to allow the body to cool in air, without resorting to liquid cooling, otherwise the body will not stand the temperature difference and crack. Cleaning the inner surface is required until the state of gloss. There should be no dross from melted varnish and copper.
It will require counting the number of turns and wire parameters. We select for rewinding magnet wire. This wiring has special properties. The shape are rounded and rectangular.
Wiring possesses very low insulation resistance. In the repair shops there are mechanical devices for winding the windings, wires are taken with increased insulation strength, the letter M is added to the marking. We rewind our own hands, so we take the wire with conventional insulation with the parameters of the previous one.
Rewind motor windings
It is necessary to rewind the windings with the help of a template; we manufacture it ourselves according to the size of the stator housing. The first thing we begin our repair cardboard laying as insulation from the body.
By pattern we make the first turn winding, then run it into the groove without biting the conductor, the wire must be intact, connected to all turns of the same phase.
Rewind should first be the turns of one phase and laid in the grooves. After snacking wiring, making loose ends. For the resulting turns, we make good insulation with cardboard.
We perform similar actions for each separate phase. Special attention needs to be paid insulation quality, to prevent interturn closures. Mark the start and end of the windings.
Strapping is necessary. The outer parts are formed into the desired geometry and tied. The turns with the cardboard should protrude 5 millimeters outside the stator housing before forming and strapping. You can use to rewind hand winding machine.
Insulation must be laid in such a way that exclude touching the case motor in the future. The condition of sufficient isolation can be checked with an ohmmeter, ringing the windings for the output ends and checking the insulation resistance on the ground-housing.
Features rewind electric motor do it yourself
Observe the number of turns needed very accurately. We have 6 coils in 2 areas. The difference between the coils will lead to a difference in the currents in the windings and, as a result, the burning of the coils.
There should be no overlap conductors when rewinding. Rewind evenly with the same distance between the wires, to facilitate the laying of the coils in the stator slot.
The template can be made to the size of two rounded sticks, connecting them at the desired distance to the number of turns of one winding. The geometry of the coils should not differ from each other. To place the turns in the stator can be used special tool - tamper.
She represents blade type with a thickness under the size of the groove and saves laying time with a large number of engines. It should be remembered coils are located in the slots of the stator with an offset. Necessary condition of the rotor in the electromagnetic field.
The upper part above the turns in the slots of the stator closed by a cardboard. We put the prepared arrows of insulating material and push them in to fix them. Interphase insulation is carried out with the same material with strapping of each turn. We lay the coils along the front of the stator.
The terminals of the coils are filled into insulating tubes and conducted into the hole that goes to the installation site boro. Tubing must be insulated by material not only having the necessary ductility, but also good temperature resistance. Wires during operation and the motor housing will be very hot.
The cut ends left after laying the insulation are assembled into the star circuit; the winding connections are produced by the method ordinary soldering soldering iron. We impose on these places the insulation tube and give the final shape of the front of the windings.
We fix them with cord thread or strapping wire and proceed to the final isolation procedure. All parts protruding beyond the body of the grooves and the stator, we well tamped.
To assemble the engine follows put the rotor in place and bait the required number of bolts. All the fixtures do not need to put, collect to measure the currents in the circuit.
Measure the currents of each phase device "current tongs". Currents must be equal in three phases and correspond to tabular data.
After testing the rotation of the engine and checking the operation at idle, disassemble the motor again.
We produce varnish coating. When the windings are soaked and all the voids are filled, the stator is placed in a suspended state for a long time. Excess varnish should drain and dry for 3 hours in the open air. You can dry the coated parts in the oven.
Having dried the engine, we carry out motor assemblycheck the insulation resistance again. Then we check the currents at idle.
- It is not recommended to turn the rewound motor into full voltage immediately. First run is run through a transformer - step-down. The motor should start to rotate weakly, the absence of smoke and burning odors indicates good operation.
- If any deviations in work are noticed, it is necessary to identify the reason for the idle motor. Only after this, having repeated the test with the help of a transformer, should be switched on to full voltage.
The result was a rewound motor.
Rewind specialists recommendations
- In determining the failure of the engine must be remembered that in quite frequent cases when the insulation resistance has fallen and has any small values, it is enough to clean the engines of dirt and dry the accumulated moisture using a stove called “thermal cannon. "
- In rare cases, the repair of old insulation is possible: if a short circuit occurs due to vibration and the place of contact under the flanges. Stripping insulation, its restoration and pour varnish will help.
- When dialing is installed interturn closure? The resistance of one winding is lower than the other. Determined by ohmmeter. You can try to determine the desired coil. To do this, you have to bite the wires between the turns and determine the resistance of each.
- In rare cases, you can remove the spoiled coil, replace it with a new one, solder the ends and check on the stand. The same steps can be used in case of short circuit.
- It is necessary to rewind the coil onto the template evenly, filling the wire to the wire, without warps, without overlaps, according to the dimensions of the stator. Otherwise there is a risk during assembly not to insert the rotor. The section and brand of wires must match the original.
Next, you should fill the winding special varnish. Be sure to check the rotation of the engine with a transformer before pouring. Then under full stress. This check will eliminate the possibility of spoiled material.
The use of calibrated instruments to determine engine parameters: resistance and no-load current. When checking in the motor power circuit should stand proper protectionconfigured above two thirds of rated current.