3 phase transformer- single phase load

[stardust]

Have a three phase 480 delta -240 delta transformer feeding a ups. The transformer is being fed with 2 legs of 480v 3 phase. 2 legs coming out to a fused disconnect, then to the ups. Ups faults - incorrect input voltage - 182v. Read 244v between hot legs. To ground read 40v one leg, 200v other. Any ideas? Print called for single phase transformer, have no idea why 3 phase was installed.

 

[retirede]

My first guess is that the UPS is expecting a conventional 240 single phase input and is looking for 120 to ground on each phase.

 

[rlundsrud]

Is there equipment at the site that is causing a temporary voltage drop (like an elevator) that might be causing the fault. If that is the cause, is there a setting on the UPS to increase the alarm delay?

 

[retirede]

Is there equipment at the site that is causing a temporary voltage drop (like an elevator) that might be causing the fault. If that is the cause, is there a setting on the UPS to increase the alarm delay?

I took the OP to mean that the UPS errors immediately on power up. But now that I read it again, it doesn’t say that.
Your scenario is plausible.

 

[texie]

Have a three phase 480 delta -240 delta transformer feeding a ups. The transformer is being fed with 2 legs of 480v 3 phase. 2 legs coming out to a fused disconnect, then to the ups. Ups faults - incorrect input voltage - 182v. Read 244v between hot legs. To ground read 40v one leg, 200v other. Any ideas? Print called for single phase transformer, have no idea why 3 phase was installed.

You're going to have to supply more info. What are the exact specs for the UPS input? You are going to get all kinds of bizarre reading with the 240 delta secondary if it is ungrounded and also missing an input phase. I am confident that any UPS will not be rated to connect to a source as you are describing.