How Do We Test the Reliability of An Induction Motor

What kind of failures?

How have you made the choice of the motors with respect to the compressors as type and output?

How are the mechanical connections between metors and compressors?

Failure of IMs are not very common. Or to be precise very rare, unless as you pointed out it is incompatible.

OP may check this up.

The second way to find is - are the motors all of same make? Are they new or repaired ? Definitely if the motors of different make are failing it must not be blamed to motors.

Third what are the current readings (and also the power). Try to get the current analysed by FFT.

Fourth (especially in case of mechanical failure) check the vibration on the motor near foot and near the shaft on Drive end face (3 places - Axial, Horiz and vertical) These will give you sufficient data to proceed with the analysis of root cause.

Finally- I second NN, it is not likely to be motor reliability issue.

hi,

i think the best way is to contact the manufacturer! if it was me, i will do it and take the easy way out!

First you should check the load and start-up conditions and the duty cycle. IMs are the most reliable motors.

Hi Umarani,

First of all please describe in detail the nature of failure. It can be due to any of the following reasons:-

1.Bad quality of the motor or not from a reliable mfrs.

2.Overloaded mechanically.

3.Not designed for the application (Compressors).

4.No protection provided in electric circuit for overload or short circuit.

5.Not properly connected with load. Misaligned coupling etc.

6.Not suitable to surrounding environment

Please better contact the mfr who can study the problem at the site and give proper

solution

Suresh Sharma

As you give so littel critical detail and I forgot to bring my crystal ball, I would suggest a motor that is at least 25% more powerful. Though there are many possibilities....as other posters have mentioned!!

Check the currents in all phasesa nd see whether it iswithin limits

second measure temp .You can use a std thermometer .add 10Deg to measured value.Check ambient add temp+ ambient and see whether it is within limits of insulation class used.Mostly in compressor duty motors have a service factor 1.2 or1.15 which means motor can be overloaded by20or15% for short duration as specified by manufacturer.but performance figs do not nessecerily hold good under these conditions like temp rise /eff etc.In compressor duty motor is load flctuates from full to almost nil .This also causes current pulsations.Mostly temp is the caues of failures,also use quality branded motors.Most compressor manufacturers supply what is cheaper for them and rarely aware of the suitabilty of a motor for the application..So make it apoit to specify the motor make while ordering the compressor package.