Three Phase Motor Test with Megger
Testing diagram and testing procedure.
1- Three Phase Motor Test with Megger:
Three phase motor is checked when it is faulty or after rewinding. Many methods are available for testing or check three phase motor. Megger test method is given below mentioned.
Three phase motor has three windings, one is R phase, second is Y phase and third is B phase. Firstly, power connection is disconnected from connection plate then motor can be tested below mentioned procedures.
2-TP motor testing diagram with Megger. :
3- Types of three phase motor test :
Mostly three types problems are found in motor as below mentioned.
- Coil open test.
- Short circuit test.
- Insulation resistance test.
4- Coil open circuit Test:
In this test all three-phase winding continuity is checked. Is it close or open? Three phase windings are marked as u, v and w that are mentioned on terminal plate as U1, V1, W1, and W2, U2, V2.
1- R phase coil open circuit test:
Turn the megger at 150 rpm and megger leads are connected with U1 and U2 terminal. if the value is zero on display. It means winding is close. If the value on display as infinity, then the winding is open or break.
2- Y phase coil open circuit test:
Turn the megger at 150 rpm and megger leads are connected with V1 and V2 terminal. if the value is zero on display. It means winding is ok. If the value on display as infinity, then the winding is short.
3- B phase coil open circuit test:
Turn the megger at 150 rpm and megger leads are connected with W1 and W2 terminal. if the value is zero on display. It means winding is ok. If the value on display as infinity then the winding is short.
5- Short Circuit Test:
In this test all three-phase winding short circuit continuity is checked. Is it short or not? Three phase windings are marked as u, v and w that are mentioned on terminal plate as U1, V1, W1, and W2, U2, V2.
A- Short circuit test between R and Y phase winding:
: Turn the megger at 150 rpm and megger leads are connected with U1, U2 and V1, V2 terminal. if the value is zero on display. It means both windings are short. If the value on display as infinity, then the both windings are ok or normal condition.
B- Short circuit test between Y and B phase winding:
Turn the megger at 150 rpm and megger leads are connected with V1, V2 and W1, W2 terminal. if the value is zero on display. It means both windings are short. If the value on display as infinity, then the both windings are ok or normal condition.
C- Short circuit test between R and B phase winding:
Turn the megger at 150 rpm and megger leads are connected with U1, U2 and W1, W2 terminal. if the value is zero on display. It means both windings are short. If the value on display as infinity, then the both windings are ok or normal condition.
D- Short circuit test between R phase winding and body:
Turn the megger at 150 rpm and megger leads are connected with U1, U2 and motor body. if the value is zero on display. It means R phase winding is short with motor body. If the value on display as infinity, then the R phase winding is not short with motor body.
E- Short circuit test between Y phase winding and body:
Turn the megger at 150 rpm and megger leads are connected with V1, V2 and motor body. if the value is zero on display. It means Y phase winding is short with motor body. If the value on display as infinity, then the Y phase winding is not short with motor body.
F- Short circuit test between B phase winding and body:
Turn the megger at 150 rpm and megger leads are connected with W1, W2 and motor body. if the value is zero on display. It means B phase winding is short with motor body. If the value on display as infinity, then the B phase winding is not short with motor body.
6- Insulation Resistance Test:
All three phase windings insulation is tested with test lamp methods. in this test all three-phase winding insulation is checked. Is it ok or failure? 3 phase windings donate as u, v and w, which are mentioned on terminal plate as U1, V1, W1, and W2, U2, V2.
1- R phase winding insulation test.
Megger is connected with U1 and U2 terminal. If the resistance is zero or low then winding insulation is weak or it has burn or failure. If the insulation is infinity or more than winding insulation is normal.
2- Y phase winding insulation test.
Megger is connected with V1 and V2 terminal. If the resistance is zero or low then winding insulation is weak or it has burn or failure. If the insulation is infinity or more than winding insulation is normal.
3- B phase winding insulation test.
Megger is connected with W1 and W2 terminal. If the resistance is zero or low then winding insulation is weak or it has burn or failure. If the insulation is infinity or more than winding insulation is normal.
