Bypass Mode; Figure 4. Path Of Current Through The Ups In Bypass Mode - Powerware 9315 Operation Manual

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 directly.
CAUTION:
The critical load is not protected while the UPS is in Bypass mode.
Figure 4 shows the path of electrical power through the UPS system when the UPS
is operating in Bypass mode.
Bypass
Input
CB1
Rectifier
Input
Path of electrical power
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). The fourth transfer will lock the critical load on the bypass source and
requires operator intervention to transfer.
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.
Powerware 9315 (200 kVA ---300 kVA) Operation
164201036 Rev. D 041500
RECTIFIER

Figure 4. Path of Current Through the UPS in Bypass Mode

BYPASS
K4
INVERTER
BATTERY
K3
(open)
TRANSFORMER
Output
11