Eaton 9315, Installation And Operation Manual

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7 − 4 EATON Powerware 9315 Parallel Capacity/Redundant System
164201150 Rev. E www.powerware.com
7.2.2 Bypass Mode
The SBM automatically switches to Bypass mode if it detects a UPM overload,
UPMs unavailable, 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 SBM is in Bypass
mode.
Figure 7−2 shows the path of electrical power through the Parallel
Capacity/Redundant system when operating in Bypass mode.
UPM1
UPM2
UPM3
UPM4
SS
FBP
CBP
CBS
BYPASS
INPUT
OUTPUT TO
CRITICAL
LOAD
BATT
UPM
INPUT
BATT
BATT
BATT
SBM
Path of Electrical Power
(open)
Figure 7−2.Path of Current Through the Parallel Capacity/Redundant System in
Bypass Mode.
You can transfer the SBM from Normal mode to Bypass mode manually. However,
the SBM switches automatically to Bypass mode whenever the UPMs can no
longer supply the critical load. If the SBM transfers to Bypass mode from Normal
mode due to an output voltage deviation, the SBM automatically attempts to
transfer back to Normal mode (up to three times within a 10-minute period). The
fourth transfer or an overload condition 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 SBM is unable to return to Normal mode following an automatic transfer to
Bypass mode, an alarm condition will be recorded.