1- Single Phase Motor Test with Megger:

Single phase motor is checked when it is faulty or after rewinding. Many methods are available for testing or check single phase motor. Megger test methods are given below mentioned.

Single phase motor has two windings, one is running winding second is starting winding. Firstly, power connection is disconnected from connection plate then motor can be tested below mentioned procedures.

Megger is a test instruments which is used in commonly for winding coil insulation test, open circuit test, short circuit test.

2-SP motor testing diagram with Megger. :

3- Types of single phase motor test :

Mostly three types problems are found in motor as below mentioned.

• Insulation resistance test.
• Coil open test.
• Short circuit test.

1- Insulation Resistance Test:

Both windings insulation is tested with multimeter. in this test running and starting winding insulation is checked. Is it ok or failure? single phase windings donate as R1, R2 and S1, S2 which are mentioned on terminal plate as main R1, starting S1 and common point R2, S2.

Firstly, both winding end points is separately as running winding R1, R2 and starting winding S1, S2. Select knob of megger at resistance mode.

A- Main or running winding insulation test.

Megger black lead endpoint is connected to the R1 and red lead point is connected with R2. Measure the resistant and note down. Main winding resistant should be low because winding conductor size is bigger than resistant will be low.

B- Starting winding insulation test.

Megger black lead endpoint is connected to the S1 and red lead point is connected with S2. Measure the resistant. And note down. Starting winding resistance should be more because winding conductor size is thin and length is more than resistance will be high. As per equation R = p l/a the area is low and length is more than resistant will be more.

2- Open Circuit Test:

Firstly, both winding end points is separately as running windingR1, R2 and starting winding S1, S2. Select knob of Megger at continuity mode.

A- Running winding open circuit test:

Megger red endpoint is connected with R1 and another black end is connected with R2. If the continuity value is available or sound is coming than winding is not open. If the sound is not coming than winding is open or break.

B- Starting winding open circuit test:

Megger red endpoint is connected with S1 and another black endpoint is connected with S2. If the continuity value is available or sound is coming than winding is not open. If the sound is not coming than winding is open or break.

3- Short Circuit Test:

Firstly, both winding end points is separately as running winding R1, R2 and starting winding S1, S2. Select knob of Megger on continuity mode.

A- Short circuit test between running and starting winding:

Megger one end is connected to the R1, R2 and second end is connected to the S1, S2. If the continuity sound is coming than both winding are short each other. if sound is not coming or value is zero then windings is not short with each other.

B- Short circuit test between running winding and motor body:

Megger lead one end connects to motor body and second end connects to the running winding R1, R2. If continuity sound is coming or value is showing something then it means running winding is short with body. If continuity sound is not coming then running winding is not short with body.

C- Short circuit test between starting winding and motor body:

Megger lead one end is connected to the body and second point is connected to the starting winding S1 and S2. If the continuity sound is coming then starting winding short with body. If the continuity sound is not coming then winding is not short with body.

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