Emerson NX User Manual

The UPS system will initiate an automatic load transfer to the bypass line if an overload condition 

exceeds the current-versus-time curve of overload capacity or if specified UPS system faults occur.
The Overload Transfer and Output Undervoltage alarm messages will initiate an automatic transfer 

to bypass. Other UPS system faults will initiate an automatic transfer to bypass followed 

immediately by the shutdown and isolation of the UPS system. Refer to 2.6.3 - Automatic Transfers 

to Bypass, UPS System Faults.

For specified UPS system faults, the control logic will initiate an automatic transfer to bypass 

followed immediately by a shutdown and isolation of the UPS system. The DC source (MBD) and 

input circuit breakers are open. The bypass static switch will be closed if the bypass line is available.

The following UPS system faults will initiate an automatic transfer to bypass:

• DC Overvoltage Shutdown
• Inverter Fault
• Low-Battery Shutdown
• Output Overvoltage and Undervoltage
• Overload Shutdown
• Equipment Overtemperature
• Rectifier Fuse Blown

Some installations may include a Remote Emergency Power Off mode that can be initiated 

automatically by a contact closure in the critical load equipment. Refer to 2.4.4 - Remote 

Emergency Power Off.

NOTE
A load transfer to the bypass line will be completed whenever an automatic transfer to bypass 

NOTE
The bypass line is usually not available during Low Battery Shutdown. 

NOTE
A load transfer to the bypass line will be completed whenever an automatic transfer to bypass