What would cause the CTR-M to turn off (fan related, Open the bypass)?

It depends on the thermal sensor mounted near SCR. When the thermal sensor operates, stop the SCR gate drive. Then, UPS will display “WARNING” on LCD, and store a log “TEMP ALARM (STS)”. In the case of the parallel redundant UPS, the UPS that detects the abnormal temperature is disconnected (parallel-off). And the normal UPS(s) […]

Are the 2 fans in the front of the cabinet on the SCR heatsink fed from the same power supply?

Yes. 2 fans are connected to one power supply. And 3 power supplies are connected to one control transformer.

It looks like there are 3 fan power supplies and each power supply runs 2 fans. (6 fans total)

Yes, 4 fans on the top and 2 fans on the front for SCR. Fuji has verified a single power supply failure. That means that 2 fans failure simulated.

Is an alarm produced for a single fan failure?

No, it is not. Only one type of caution message is displayed. Please visually check it because you do not know which fan has failed.

Please provide a brief comment on a single fan failure in a CTR-M.

Each fan has a speed alarm. When any one alarm is detected, UPS will display “CAUTION” on LCD, and store a log “CTR FAN ERROR”. CTR-M continues running.

What would cause the UPM to turn off? (fan related)

UPS will continue running until IGBT thermal sensor operates (rectifier, inverter or chopper).

It looks like there are 3 fan power supplies and each power supply runs 2 fans. (6 fans total)

Yes, on the top. Fuji has verified a single power supply failure. That means that 2 fans failure simulated.

Is an alarm produced for a single fan failure?

No, it is not. Only one type of caution message is displayed. Please visually check it because you do not know which fan has failed.

Please provide a brief comment on a single fan failure in a UPM.

Each fan has a speed alarm. When any one alarm is detected, UPS will display “CAUTION” on LCD, and store a log “FAN ERROR”. UPM continues running.

What is the trade-off relation of the IGBT power devices?

The trade-off relationship of an IGBT describes the relation between ON-state conduction losses, switching losses and short circuit withstand capability. An IGBT can be optimized for either one. For example, when reducing the conduction losses, the switching losses will increase and the short circuit withstand capability decrease.