My Eaton UPS 9390 120KVA is malfunction with bypass

hples2020 · Feb 29, 2020

My Eaton UPS 9390 120KVA is malfunction. The active alarm now is “ALRM: CHECK BYPASS SWITCH” . We get the following status/alarm logs when we try to power UPS and press BYPASS at menu on display:

1. When power on UPS:

- STATUS: CONTROL POWER STATUS ON

- ALARM: CONFIGURATION ERROR 34

- NOTICE: OUTPUT AC UNDER VOLTAGE

- STATUS: INVERTER SWITCHGEAR OPEN

- STATUS: BATTERY SWITCHGEAR OPEN

- STATUS: BYPASS SWITCHGEAR OPEN

- ALARM: CHECK BYPASS SWITCHGEAR

- NOTICE: BYP SOURCE OUT OF TOLERANCE

- ALARM: CHECK BYPASS

- ALARM: CHECK STATIC SWITCH 1

- ALARM: CHECK STATIC SWITCH 2

- ALARM: CHECK STATIC SWITCH 3

- ALARM: CHECK BYPASS SWITCHGEAR OK

- ALARM: CHECK BYPASS OK

- ALARM: CHECK BYPASS SWITCHGEAR

- ALARM: CHECK STATIC SWITCH 1

- ALARM: CHECK STATIC SWITCH 2

- ALARM: CHECK STATIC SWITCH 3

- ALARM: CHECK BYPASS SWITCHGEAR OK

- ALARM: CHECK BYPASS SWITCHGEAR

- ALARM: CHECK BYPASS SWITCHGEAR OK

- ALARM: CHECK BYPASS SWITCHGEAR

- ALARM: CHECK BYPASS SWITCHGEAR OK

- NOTICE: BYP SOURCE OUT OF TOLERANCE OK

- ALARM: CHECK BYPASS SWITCHGEAR

2. When press BYPASS at menu to force UPS go to bypass:

- CMD: TO BYPASS COMMAND

- ALARM: CHECK STATIC SWITCH OK

- ALARM: CHECK BYPASS SWITCHGEAR

- NOTICE: BYP SOURCE OUT OF TOLERANCE

- ALARM: CHECK STATIC SWITCH 1

- ALARM: CHECK STATIC SWITCH 2

- ALARM: CHECK STATIC SWITCH 3

- ALARM: CHECK BYPASS SWITCHGEAR OK

- ALARM: CHECK BYPASS SWITCHGEAR

- ALARM: CHECK BYPASS SWITCHGEAR OK

- ALARM: CHECK BYPASS SWITCHGEAR

- ALARM: CHECK BYPASS SWITCHGEAR OK

- NOTICE: BYP SOURCE OUT OF TOLERANCE

We have isolated UPS from the sytem (disconnect the load, disconnect battery) and done the following works to slove the problem:

- Inspect the circuit boards, parts…but no burn found.

- Clean boards: 3 power boards, 01 control board, 01 static switch board..

- Inspect static switch board, not sure OK or not OK.

- Inspect 3 thyristers, they seem OK.

- Remove the static switchgear (K5) out the UPS and test, K5 seems OK.

We have also replaced the Static Switch Board with spare board but this did not solve the problem.

What is happening with my UPS? What can I check more and solve the issue?

If you need more information, please let me know.

Thanks.

marconi · Mar 3, 2020

hples2020: Greetings from London.

Could you tell me please whether your UPS is single feed or dual feed? By this I mean is there one shared supply to the Rectifier-Inverter(R-I) and to the Bypass(BYP) or does the R-I use a different supply to the BYP?

If dual feed is the second supply derived from the first or not? If it is not could you tell me where it originates from?

Could you measure and tell me the line-to-line voltages you measure for the R-I input and also the BYP input.

Sorry to ask the obvious but have you checked the backfeed contactor K5 and the fuses between it and the static switch?

marconi · Mar 4, 2020

One of the messages is 'BYP(bypass) source out of tolerance'. This is the voltage and frequency specification - are the line voltages and frequencies of the feeds in range:

208 Vac for operation from 177 Vac to 229 Vac
220 Vac for operation from 187 Vac to 242 Vac
380 Vac for operation from 323 Vac to 418 Vac
400 Vac for operation from 340 Vac to 440 Vac
415 Vac for operation from 353 Vac to 457 Vac
480 Vac for operation from 408 Vac to 528 Vac

Has the UPS been 'told' what the normal voltage and frequency are? I recommend you either check or re-input them.

Is there much variation of the input voltage and frequency over time? Too much change or too high a rate of change of either may be detected as an unstable/low quality supply by the UPS preventing changeover to bypass - this might be the case if the second feed for the bypass was derived from a generator.

Are all lines present and energised and do both feeds have the same phase rotation sequence?
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Does your 9390 have the 'Sidecar'?

marconi · Mar 4, 2020

Will the UPS run up correctly in Normal mode ie: Power to Input A(UPS) to rectifier - inverter with battery on float? Is the ac output voltage and frequency to the critical load output correct in Normal mode?

DPG · Mar 4, 2020

I think you're chatting to yourself Marconi.

marconi · Mar 4, 2020

See page 7-1 Fig 7.1 of:

https://www.eaton.com/content/dam/e...al-serial-number-7th-digit-at-A-164201554.pdf

hples2020 and DPG: Noting the message 'Configuration Error 34' and 'BYP Source out of tolerance' my musings at the moment are:

1. The second feed input (B) for the Bypass pathway is of a voltage, frequency, or has excessive temporal variation such that the UPS switchover to Bypass logic regards it as out of tolerance and hence unsuitable to power the critical load - so Bypass remains open even when commanded. This might be because the second feed is indeed out of tolerance or because the UPS's preset values (viz the configuration values) for critical output voltage and frequency are wrong or so far removed from what the second feed can provide that there is a mismatch preventing selection of Bypass Mode.

2. A derivative of 1 above - one or more of the line voltages is/are out of specification.

3. The circuitry which monitors and measures the second feed's voltage and frequency is defective.

4. The inverter's frequency control cannot track the second feed's frequency variation sufficiently well to briefly synchronise with the second feed to allow a quarter cycle of handover during which both inverter and second feed (via static switch) are both supplying the load momentarily before the inverter output contactor K3 opens (make before break transfer). Similar thinking for the inverter voltage control.....

5. A derivative of 4 - the UPS inverter is configured to output say 50Hz (tolerance +/- 5Hz) and the second feed is 60Hz (or vice versa). Or the inverter is set to output say 380V ac nominal (acceptable range 323-418V) and the second feed for bypass has voltage of 430V. In neither case can the inverter adjust its voltage and/or frequency to match the second feed - it would be so much of a mismatch as to be wholly unacceptable to the critical load - so the make before break transfer is barred from happening to enter the Bypass Mode.

I think 'Configuration Error 34' and 'BYP source out of tolerance' are the salient messages on what is the problem.

Or something along these lines....