Emerson 50 and 60 Hz User Manual

The bypass cabinet enables maintenance operations and repairs to be performed in full isolation 

while also allowing the disabling of each UPS without affecting the ordinary operation of the system 

(depending on the redundancy level).
The optional maintenance bypass cabinet must be used in all configurations where one internal main-

tenance bypass switch is insufficient to supply the full system load.
Each kVA rating has maintenance bypass cabinets sufficient to supply the full system load up to six 

units in parallel power operation.

Interlock the External Maintenance Bypass Switch with the operation of the UPS module(s) prevents 

backfeed of the External Bypass AC power into the Inverter if an incorrect switching sequence is 

used. A volt-free auxiliary status contact from external bypass switch QF3 is connected to UPS termi-

nal X3 (MBC interface) of the parallel control board (M3).

4P

4P

400V, 50Hz

4W

S

Q1

Q2

Q3

Q5

X3

X1

CB

4P

Q1

Q2

Q3

Q5

X3

X1

CB

4P

UPS2

UPS3

400V, 50Hz
3 or 4W

400V, 50Hz

4W

Supplied
by Others

Q1

Q2

Q3

Q5

X3

X1

CB

4P

UPS1