Powerware 9390 operation manual Understanding UPS Operation

Understanding UPS Operation

The neutral from the system input is connected to the neutral regulator in the DC capacitors. The output neutral of the system is connected with the required neutral supplied at the utility bypass input and should never be bonded to ground at the module’s output.

The inverter produces a three-phase AC output to a customer’s load without the use of a transformer. The inverter derives regulated DC from the rectifier and uses IGBT devices and pulse-width modulation (PWM) to produce a regulated and filtered AC output. The AC output of the inverter is delivered to the system output through the output contactor K3.

If the utility AC power is interrupted or is out of specification, the UPS automatically switches to Battery mode to support the critical load without interruption. When utility power returns, the UPS returns to Normal mode.

If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode. The UPS automatically returns to Normal mode when the overload condition is cleared and system operation is restored within specified limits.

If the UPS suffers an internal failure, it switches automatically to Bypass mode and remains in that mode until the failure is corrected and the UPS is back in service.

Powerware® 9390 UPS (40–80 kVA) Installation and Operation Manual S 164201535 Rev C 7-5