How to identify the turn-to-turn fault of motor winding

It is inevitable that the motor will fail in one way or another during use, so how do we identify it and where is the problem?

Today we will tell you:

How to simply identify winding turn-to-turn fault?

No matter what it is, if you read it more, you must have more objective and direct judgment ability. Today, we will introduce a method to judge turn-to-turn fault through actual fault cases.

What is turn-to-turn fault?

The same winding consists of many coils. If the insulation is not good, there will be a short circuit between the superimposed coils, which means that some coils are directly short-circuited and have no effect. After inter-turn short circuit, the winding magnetic field of the motor will be asymmetric, and the current of the remaining coils will increase than before. During the operation of the motor, there will be problems such as increased vibration, increased current and relatively reduced output.

When the motor is running, whether in experimental operation or actual operation, if turn-to-turn fault occurs, the most direct phenomena are current imbalance, burning smell, dull motor sound and obvious vibration problems, especially smoking and shooting.

In the process of disassembling the faulty motor, we will find it difficult to distinguish between phase-to-phase fault, ground fault and turn-to-turn fault. Today, I will only talk about the screening method of turning the topic.

Let's show you a picture of a faulty rotor. Can you tell what the fault is from the signs of the fault? This is a real photo taken at the scene of fault analysis. At that time, some people thought it was wandering around, others thought it was interphase, and the final result was interphase, or it could be considered that interphase was the main reason.

Fault cause analysis

For this kind of problem, we first comprehensively analyze the location of the fault point and the spread of the fault. The fault point is just in the phase-to-phase insulation position, which is a necessary condition for phase-to-phase fault; The second step is to put aside the phenomenon and explore the essence, that is, look at the opposite position of the fault point, that is, look at the other end of the winding. If it is a turn-to-turn fault, there will be a light burn mark on the opposite side, otherwise it is a turn-to-turn problem. The actual inspection shows that the winding fault point is limited to local terminals and is a typical phase-to-phase fault. We will share with you the analysis of the causes of winding phase-to-phase faults in the later period with practical cases.