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S&C Instruction Sheet 653-502
System Operation
Under normal conditions, power is supplied from the utility grid to the critical load
through the input circuit breaker, PES, and output isolation circuit breaker.
The system’s utility disturbance monitor (UDM) continuously monitors the supply volt-
age for disturbance activity. When a disturbance occurs, the PureWave UPS System turns on
the system’s high-power inverter(s). The stored energy in the system’s batteries is converted
to ac and supplied through a voltage-matching isolation transformer while the PES is com-
manded off (open) to isolate the customer’s critical loads from the faulted utility. Output
power matches the customer load for one minute at full load (or up to three minutes at
reduced power) during the utility voltage disturbance or momentary power interruption.
The entire transfer sequence occurs typically within 1 to 4 milliseconds (less than ¼
cycle). An electrically operated bypass circuit breaker permits continued service to the
customer from the utility in the event the PureWave UPS System is out of service for
maintenance. See Figure 15 for a diagram of the PureWave UPS System
.
Operation
Figure 15. Diagram of the PureWave UPS System.