Emerson NX Manuel D’Utilisation

In this operating mode, the connected loads are supplied from line power via the Static Bypass 

Switch. The Static Bypass Switch is used to provide power to the loads. If an overload or short-circuit 

on UPS output occurs, the Static Bypass Switch is automatically activated to provide uninterrupted 

power to the loads. The Bypass operating condition is displayed. From this operating mode, the UPS 

automatically reverts to on-line operation after the fault is corrected. Bypass operation can also be 

specifically selected from the control panel using the push button.
Load on Bypass is shown in Figure 13. The UPS system could be in this mode of operation during 

either initial startup or UPS system shutdown or isolation for maintenance.

Risk of unexpected power loss. Can cause equipment damage.
When the critical load is being supplied power from the bypass line, the load is vulnerable to 

utility failure and fluctuations.

DC 

Bus

BFB

UPS Module

To DC Supply

Module Rectifier
AC Input

Module Bypass 
AC Input

UPS Output

Critical 

Load

DC 

Bus

BFB

UPS Module

To DC Supply

Module Rectifier
AC Input

Module Bypass 
AC Input

UPS Output

Critical 

Load

BFB

UPS Module

To DC Supply

Module Rectifier
AC Input

Module Bypass 
AC Input

UPS Output

Critical 

Load

DC 

Bus