Three Phase Motor Test
Types of Test, Procedure and Testing Methods.
1- Three Phase Motor Test:
Three phase motor is used widely in domestic, residential, societies , industries and commercial. We utilize to the motor as different types but sometimes motor does not work then we think what happened. If the motor is malfunctioning then the motor will have to test. After testing we can know about actual situation of motor health. Here we are going to discuss about single phase motor.
2- Connection diagram of three phase motor test:
3- Types of three phase motor test:
Mostly three types problems are found in motor as below mentioned.
- Winding insulation resistance test.
- Winding coil open test.
- Short circuit test.
A- Insulation resistance test:
Insulation resistance test is carried out or implemented on running and starting winding. After this we can know about both windings insulation is ok or not. This test can be done as two types like as testing lamp methods and multimeter methods.
B- Open circuit test:
Open circuit test is carried out or implemented on running and starting winding. After this we can know about both windings open or close. This test can be done as two types like as testing lamp methods and multimeter methods.
C- Short circuit test:
Short circuit test is carried out or implemented on running and starting winding. After this we can know about both windings is short or not body or each other. This test can be done as two types like as testing lamp methods and multimeter methods.
4- Types of testing methods:
When motor does not works then we had to check for fault finding. Three types motor testing methods are available just like below mentioned.
- Testing lamp test methods.
- Multimeter test methods.
- Megger test methods.
1- Testing lamp test methods:
Three phase motor is checked when it is faulty or after rewinding. Many methods are available for testing or check three phase motor. Testing lamp method is a popular testing method. It is an instrument test circuit which is connected in series with faulty Equipment.
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.
A- 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. First check and separate all three windings pairs like as U1U2, V1V2, W1W2.
We will have to check all three phase coil pair one by one with testing lamp. R phase windings end points U1 is connected with test lamp B points. The power supply is applied into rest U2 and A points. If the lamp is glowing dim then the coil insulation is normal or ok. If the lamp is glowing brightly then the coil insulation is not ok. This testing procedure will be followed one by one other rest phase Y and B.
B- 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.
We will have to check all three phase coil pair one by one with testing lamp. R phase windings end points U1 is connected with test lamp B points. The power supply is applied into rest U2 and A points. If the lamp is glowing then the coil is not break or ok. If the lamp is not glowing then the coil is break or not ok. This testing procedure will be followed one by one other rest phase Y and B
C- Short circuit test:
In this test all three-phase winding continuity is checked with each other and motor body. Three phase windings are donated as u, v and w that are mentioned on terminal plate as U1, V1, W1, and W2, U2, V2.
First we will have to test R and Y phase. Test lamp A points is connected R phase and B phase is connected with Y phase then the power supply is applied. If the lamp is glowing then R and Y coil is short. If the lamp is not glowing then the R and Y phase winding is not short in each other. Same type procedure will be followed on YB, RY an R with body, Y with body, B with body.
2- Multimeter test methods:
Three phase motor is checked when it is faulty or after rewinding. Many methods are available for testing or check three phase motor. Multimeter test method is given below mentioned.
A- Insulation resistance test:
All three-phase windings insulation is tested with multimeter 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. Multimeter knob is selected on resistance mode for resistance checking.
Multimeter leads is connected with U1 and U2 terminal. The value of resistance should be note down. Same procedure will be followed with other phases Y and B. All three phases resistance will have to comparison. If any phase resistance low then this phase in not working.
B- 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. Select the multimeter knob on the continuity mode.
Multimeter leads are connected with U1 and U2 terminal. If the continuity sound is coming or value on screen is something then winding is close. If the continuity sound is not coming or value is zero then the winding is open or break. Same testing procedure will be followed on other phases Y ans B one by one.
C- Short circuit test:
In this test all three-phase winding continuity is checked with each other and motor body. Three phase windings are donated as u, v and w that are mentioned on terminal plate as U1, V1, W1, and W2, U2, V2. Select the multimeter knob on the continuity mode.
Multimeter leads are connected with R and Y phase winding as terminal U1, U2 with V1, V2 terminal. If the continuity sound is coming or value is showing something. It means both winding is short condition. If continuity sound is not coming or value is zero. It means the windings are not short or ok condition.
Same procedure will be followed on other phase Y and B, R and B, R with body, Y with body, B with body.
3- Megger test methods:
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.
A- Insulation resistance test:
In this test all three-phase winding insulation is checked. Is it normal or not normal? Three phase windings are marked as u, v and w that are mentioned on terminal plate as U1, V1, W1, and W2, U2, V2.
Turn the megger at 150 rpm and megger leads are connected with U1 and U2 terminal. if the value is zero or something on display. It means winding insulation is not ok. If the value on display as infinity, then the winding insulation is normal. This testing procedure will be followed on Other phases Y and B
B- 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.
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 ok. If the value on display as infinity, then the winding is short. This testing procedure will be followed on Other phases Y and B
C- 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.
Test R phase with 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.
Same procedure will be followed on other phases Y and B, R and B, R with body, Y with body, B with body.
