Motor Insulation Resistance Testing

Depends on the standard to which the motor was built. Do you know what that was?

What DO you know?

IEC motors

Probably

i do not have a copy of that .so you can please tell me what is in this code regarding my question.

I don't have a copy, either. You should buy one, or ask the motor manufacturer for this information. I don't deal with electric motors any more.

If the motor has always been operated within the specified parameters, then the insulation life should not be a concern until the motor has been in operation for however many hours are specified for its particular insulation class. You can find the class on the nameplate, then maybe you can search for the information yourself, or call the manufacturer.

Be realistic lyn, coolyaar buy a publication and read it?

coolyaar if you really need this information you're company would have no problem buying it for you and the company in general.

Its a simple test, why not just test it anyway? Is there some limiting factor such as cost, minimal resources, remote location, etc etc. Or, is this for a maintenance plan or something similar?

The only reason you should test a motor is if....

1. it has tripped on overload

2. it has blown a fuse

3. been immersed in water

4. subjected to extreme heat

Please feel free to add to this list.....

As for testing a motor "in service".... I see no benefit, and continual testing with a "insulation tester" has been proven to damage the winding insulation.

I have seen motors (and I'm sure others have too) that have been tested, and then fail after 30 seconds, 30 minutes, 30 hours etc.... so if it's gonna blow.... it's gonna blow, and it don't matter what test you do to it!!

It depend on so many factors like- HT or LT motor, insulation class, indoor or outdoor installation, protection type, ambient temp & RH etc.

As of I know, there is no specific standard for it. The reason we need to check is the ingress of moisture & dust along with air inside the winding space and affecting insulation resistance. In rainy season or hot & humid atmosphere it need to be checked more frequently compared to dry and winter weather. So it may range from 10 days to 45 days.

Now a days you can get motors (generally above 15 kW) along with built-in heaters with auto start and shut-off facilities based on timer or temp to protect the insulation resistance. In such motors there is no need to check it.

its your choice.

What's your ISO norms stats?

You can test every 6 months / 12 months / 24 months. depend upon the application /environment in which motor is running / any tripping faced etc...

If the motor is placed in Hazardous area, definitely, every time after a gap you start motor, one should check as a safety.

otherwise, no need.

Harry.. the LAST thing you want to do in a hazardous area is introduce a spark potential, as you would/could get from using a 1000v "insulation tester"

Safety first!!

Mr. Brich,

5. In case of burn smell

6. Observe smoke

if I found my motor with either one, then I would not waste my time testing!

New motor!!

At the time when you want to run it.