3 Phase Rotation with GenSet Question

[snydl0ga]

We have 3 phase Utility with ABC rotation. The GenSet Is connected to an ATS and the GenSet puts out ABC, according to our phase rotation monitor.

The issue is when the power is out and we run on the GenSet some of our motors run backwards.

I know it is a strange statement but I checked the rotations of both Utility and GenSet when we installed the generator.

Opened to suggestions.

 

[Jraef]

Are the ones that run backward 3 phase motors or single phase motors?

 

[kwired]

Did you check rotation of both sources at the transfer switch or just at each source?

If something got crossed over between either source and transfer switch then there could easily be opposite rotation from each transfer switch input.

I know it is a strange statement too, but something really simple is likely being overlooked.

 

[ceb58]

Did you check rotation of both sources at the transfer switch or just at each source?

If something got crossed over between either source and transfer switch then there could easily be opposite rotation from each transfer switch input.

I know it is a strange statement too, but something really simple is likely being overlooked.

I agree something is crossed. Crank the generator and check rotation on the generator lugs and the utility lugs in the transfer switch. You may want to verify the readings with another rotation meter to make sure you are getting correct readings.