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Operation 105
3.4.4 Automatic Module Off-Line
For specified UPS module faults, the control logic will initiate an automatic isolation and shutdown of the UPS
module. In the Module Off-Line mode the output, battery (MBD), and input circuit breakers are open. If the UPS
system was operating in the redundant mode when the module was taken off-line, the critical load will remain on
the UPS system. If the UPS system was operating in the non-redundant mode, an automatic transfer to bypass
will be initiated. Note that the bypass line is usually not available during Low Battery Shutdown. One Module
Off-Line is illustrated in Figure 52.
The following UPS module faults will initiate an automatic Module Off-Line:
DC Over-Voltage Shutdown
Hardware Shutdown
Inverter Fault
Low-Battery Shutdown
Overload Shutdown
Over-Temperature Timeout
Rectifier Fuse Blown
Reverse Power
Refer to Table 1 for more information regarding these alarm messages.
3.4.5 Automatic Emergency Modules Off
For the specified UPS system fault, the control logic will initiate an automatic transfer to bypass followed imme-
diately by a shutdown and isolation of the UPS system. In the Emergency Modules Off mode the output, battery
(MBD), and input circuit breakers at each UPS module are open. The System Bypass Breaker (SBB) will be
closed if the bypass line is available. Emergency Modules Off is illustrated in Figure 54.
The following UPS system fault will initiate an automatic Emergency Modules Off:
Output Over Voltage
Refer to Table 1 for more information regarding alarm messages.
Your installation may include a Remote Emergency Power Off mode that can be initiated automatically by a
contact closure in the critical load equipment. Refer to 3.2.8 - Emergency Power Off.
NOTE
A load transfer to the bypass line will be completed whenever an automatic transfer
to bypass is initiated and the bypass line is available. If the OK to Transfer condition
is present, the load transfer will be uninterrupted. If the Static Switch Unable alarm
message is present for any reason, the automatic transfer will be interrupted for 40 to
120 milliseconds. Because of the reliability of the UPS components, an interrupted
load transfer is a very unlikely occurrence.