How to determine winding short circuit

In the coils the field coils can sometimes happen interturn short circuit. The reason for this faulty coils is mechanical damage or destruction of the winding insulation overheating. The result is a decrease in the resistance of the winding, which in turn increases the current. The winding temperature increases and leads to the closure of a number of turns of the coil. It is therefore necessary to identify the presence of short-circuited turns as early as possible.

You will need

• - ohmmeter;
• - ammeter;
• - the voltmeter;
• - portable flaw detector.

Instruction

1. Shorted turns in the coil winding define, measure coil resistance using an ohmmeter, or by removing the ammeter (voltmeter) when powered coil from the battery. Record the readings of the measuring device. Divide the voltage value of the current and calculate the resistance. If coil resistance was less (compared to nominal) and the short turns. Troubleshooting the rewind coil or its replacement.
2. To check the coil for a short use also another method. Connect it through an ammeter to the battery. Measure the amperage in the circuit of the winding. Now measure the amperage in the circuit of the winding other coil, known good. If the circuit is missing, both measurements will show approximately the same current.
3. For the detection of interturn short circuit in the windings of electric machines use a portable flaw detector. Connect the device to a power source and place it in the bore of the stator to the groove sections check the winding located between the air gaps of the steel packages flaw. About inter-turn short circuit will signal fire on the instrument lamp.
4. To manufacture the simplest flaw detector collect electrical steel core. Pull the core plates by bolts, isolated from steel strips. Wind on a core of 800 turns of wire of brand of PEV-section of 0.8 mm.
   
5. To check the windings put her on the "shoulders" of the device core. Put on plate, steel plate from tinplate. Connect the coil of the device to the network. Now slowly rotate the coil holding plate. If one of the pairs of windings the insulation is damaged, the steel plate is drawn.
6. By visual inspection the presence of interturn short-circuit without special equipment determined by the local destruction of the windings. Note also this sign as "coking" of oil and the interior surfaces of the device. Often with inter-turn short circuit will trigger automatic protection at start-up of the unit.