Switched Reluctance Motor Inductance Test

[Leendabests]

Dear All,

I have done an inductance and winding resistance test for 75 KW SRM Motor. How could I determine whether the motor is in good condition or not based on the Inductance test result. The test has been done offline.

1) Inductance test at 100 HZ using LCR Meter :
A1-A2 @ 100Hz Lmin = 0.93
A1-A2 @ 100Hz Lmax = 4.38
A phase Lmax/Lmin Ratio = 4.38/0.93

B1-B2 @ 100Hz Lmin = 1.63
B1-B2 @ 100Hz Lmax = 5.24
B phase Lmax/Lmin Ratio = 5.24/1.63

C1-C2 @ 100Hz Lmin = 0.44
C1-C2 @ 100Hz Lmax = 0.48
C phase Lmax/Lmin Ratio = 0.48/0.44

2) Insulation Resistance Test at 1000 V:
A1 or A2 to earth = 0.8 GΩ
B1 or B2 to earth = 0.9 GΩ
C1 or C2 to earth = 0.9 GΩ

A1 –B1 = 2.2 GΩ
A1 –B1 = 2.1 GΩ
A1 –B1 = 2.2 GΩ

3) Winding Resistance Test :
A1 - A2 = 0.4 Ω
B1 - B2 = 0.3 Ω
C1 - C2 = 0.3 Ω


Thank you.

 

[dArsonval]

What about inductance variation with respect to the rotor position?
Was the test performed on an assembled motor, or with the rotor removed?

John

 

[Leendabests]

The test has been made on assembled motor. We just rotate the rotor and take the inductance reading without knowing the rotor position.

 

[cswilson]

I don't know much about SR failure modes, but I don't see how you could get any torque out of Phase C, since the torque is proportional to dL/dTheta. I am also uncomfortable about the difference between A and B values.

 

[dArsonval]

An assembled motor can, will, and does give erroneous winding test results.

John

 

[Leendabests]

According to R.Krishnan,‘‘Switched Reluctance Motor Drives, Modeling, Simulation, Analysis, Design, and
Applications’’. The range of the ratio between unaligned and aligned inductance should be 0.07 < Lmin/Lmax < 0.18 which Lmin is unaligned and Lmax is aligned rotor. Can it be used as reference since we don't know the rotor position?

 

[flexoprinting]

Watch your LCR meter as you rotate the motor slightly between rotor bars you will see quite a change, I think in
EE speak this is called "Q" factor however I agree with previous replies, position of rotor is significant.

Chuck