motor pm

[elecguy21]

I am at this company that does what they call pm on their motors. what i saw was the maintenance man take a shot from their fluke temperture meter and another test with a vibration meter and that was it. both meters appeared to be at the bottom of their product line, if that makes a differrence.
should there be more on the pm list? and if so, what would you do? some of these motors are outdoors.

 

[masterinbama]

I would also do an amp draw reading at this time. It is also important to write these results down for comparison at the next PM interval.
Most of the motors at the Water plants I contract with have GE Multilin MPR's or equivalent.
These can be linked together and monitored on a PC. You can pull up start current, full load current, and motor starting curves.

 

[Besoeker]

I am at this company that does what they call pm on their motors. what i saw was the maintenance man take a shot from their fluke temperture meter and another test with a vibration meter and that was it. both meters appeared to be at the bottom of their product line, if that makes a differrence.
should there be more on the pm list? and if so, what would you do? some of these motors are outdoors.

I think the extent of the tests depends on a number of aspects of the application.
How critical it is, and what the consequences of failure would be, for example.
More tests cost more money. If it's a small motor that won't significantly affect plant output, it might just be cheaper to let it fail and replace it if/when it does.
On the other hand if it is say, the main compressor motor in a LNG plant, all the monitoring would already be part of the system.
In short, there is no one size fits all but thermal and vibration measurements are, in my opinion, a good basic indication.

 

[ptonsparky]

Vibration meter. Mmmm, sounds like a new toy for the tool box. Anyone have preferences as to brand?

 

[masterinbama]

I can't find the one I own,but this one is close. They are really handy at finding bearing and coupling problems. Then again I worked with an old millwright years ago that would just balance a nickel on edge to detect vibration.

 

[zog]

I am at this company that does what they call pm on their motors. what i saw was the maintenance man take a shot from their fluke temperture meter and another test with a vibration meter and that was it. both meters appeared to be at the bottom of their product line, if that makes a differrence.
should there be more on the pm list? and if so, what would you do? some of these motors are outdoors.

There are a lot of tests that should be done on motors, the recommended tests depend on the size, voltage, type and AC or DC. I suggest to refer to the ANSI/NETA testing standard or NFPA 70B.

 

[billsnuff]

We track and trend every motor (on the critical-to-operations list) in the building:

Temperature - same location on motor each time (its marked)
Vibration - Front top, front side, RT and RS (vib tags attached)
Amp draw. (read at MCC)

Recorded quarterly and trended over 18month time period.......we try not to run to failure. Sometimes running to failure is the less expensive option, depends on the application. Also, test equipment is tested and calibrated annually.

 

[Besoeker]

We track and trend every motor (on the critical-to-operations list) in the building:

Temperature - same location on motor each time (its marked)
Vibration - Front top, front side, RT and RS (vib tags attached)
Amp draw. (read at MCC)

Recorded quarterly and trended over 18month time period.......we try not to run to failure. Sometimes running to failure is the less expensive option, depends on the application. Also, test equipment is tested and calibrated annually.

Good philosophy there in my opinion.
We have annual maintenance contracts with many of our customers, particularly those in the process industries where downtime can be megabucks. We are electrical engineers so we generally don't get involved in vibration measurement but we normally check to see if any abnormal readings can be correlated to the drive system.

 

[jdsmith]

...Most of the motors at the Water plants I contract with have GE Multilin MPR's or equivalent.
These can be linked together and monitored on a PC. You can pull up start current, full load current, and motor starting curves.

We have around 200 Multilins installed right now and have another 290 on order as part of four new unit substations. The nice things about the Multilins is that they are a solid state protective relay that includes the classical trip settings with the option to fine-tune trip settings a lot more on some critical applications. We do have ours networked with GE's power monitoring control system (PMCS system). Very expensive to have GE do the integration work, but they do a good job and you can view all of the voltages and currents, long time trends of all numerical data, time of last trip, reason for trip, number of trips, running hours since last PM activity, and the list goes on and on. The other key selling point for us was the waveform capture feature. Any time a trip occurs an oscilloscope-type waveform capture is triggered and sent back to the computer that runs the system. This lets us pinpoint very quickly the root cause when a few 5 kV motors trip along with 6-8 switchgear breakers all spread among 5 or more substations. The reduction in downtime had been significant because of the ability to troubleshoot the problem and see the waveforms from when the event occurred.

 

[Mule]

I am at this company that does what they call pm on their motors. what i saw was the maintenance man take a shot from their fluke temperture meter and another test with a vibration meter and that was it. both meters appeared to be at the bottom of their product line, if that makes a differrence.
should there be more on the pm list? and if so, what would you do? some of these motors are outdoors.

The way I understand it, is that the smaller vibration probes (IRD makes one) just measure "peak to peak", and I been a part of a PM program in the past where simular test where done using smaller instrument, and if the readings where greater than a certain threashold, then a more intense vibration analysis is performed to find the root cause.

As for the temperature probe, a ambient temperature can be shot of a near by mass, and then measure the degrees of rise on motor, bearing hot spots, and/or winding areas. Here again if the temperature is suspect, then a more intense test can be done with IR.............