symmetra lx and generator

[Anonymous user]

We have a symmetra lx ups in our data center that is backed up with a 30k generator. Recently when I go to test the generator the ups goes on battery durring the test. On the lcd it reads that the voltage in is 127v. Is that to high for the ups to correct? Is is something I need to have my generator guys take a look at? Thanks for your help.

[Anonymous user]

127V is what it show on the LCD not sure if that is average or which leg it would be. UPS does not give a reason that it is on battery. Atleast not one I see. The load is 45% on 12k and the breakers are two 10k.

[Anonymous user]

There should be ~120v N&L1 as well as N&L2. The two values shouldn't be apart significantly. ~208 between L1&L2 +/- 10% shouldn't be a problem for that UPS. If this isn't making sense, don't do it yourself for your own safety.

Take the three measurements twice. Once using a true RMS(such as Fluke 87). Once using a non true RMS(the common cheap meter) It is ok for the measured value to be within 10%, but if both meters' readings aren't close together, you have harmonic distortions which the UPS will think the power quality is too poor for online operation.

In this case, get an electrician to come to your site with a power quality analyzer.

N+1 brought a good point. While you're at it, check the frequency with the DMM too.

Message was edited by: KVAr

[BillP]

Typically, when it comes to generators, the frequency is often the cause of the UPS still being on battery. Does the UPS report a site wiring fault at all? What size is the generator?

[Anonymous user · Accepted solution]

We have a symmetra lx ups in our data center that is backed up with a 30k generator. Recently when I go to test the generator the ups goes on battery durring the test. On the lcd it reads that the voltage in is 127v. Is that to high for the ups to correct? Is is something I need to have my generator guys take a look at? Thanks for your help.