Powerware 5075 kVA operation manual Path of Current Through the UPS in Bypass Mode

Bypass Mode

The UPS automatically switches to Bypass mode if it detects an overload, load fault, or internal failure. The bypass source supplies the commercial AC power to the load through an internal switch and an internal transformer.

CAUTION:

The critical load is not protected while the UPS is in Bypass mode.

Figure 19 shows the path of electrical power through the UPS system when the UPS is operating in Bypass mode.

Rectifier Input

BYPASS

K4

RECTIFIER

CB1

		Bypass
	(BIB)	Input
	(closed)
		(MBP)
		(open)
	OUTPUT
	TRANSFORMER
K3		Output
	(MIS)
	(closed)
(closed)

Input

Isolation

Transformer

DC/DC

CONVERTER

CB2

(closed)

BATTERY

Path of electrical power

Figure 19. Path of Current Through the UPS in Bypass Mode

You can transfer the UPS from Normal mode to Bypass mode manually. However, the UPS switches automatically to Bypass mode whenever the inverter can no longer supply the critical load. If the UPS transfers to Bypass mode from Normal mode due to any reason other than operator intervention, the UPS automatically attempts to transfer back to Normal mode (up to three times within a 10-minute period).

Bypass mode is a normal operating mode, and not an alarm condition. However, if the UPS is unable to return to Normal mode following an automatic transfer to Bypass mode, an alarm condition will be recorded.

42 Powerware BPIII Harsh Environment UPS 50--75 kV Installation and Operation

164291261 Rev. F 111503