Emerson 250-400kVA - Manual (Page 28)

Operation
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2.3.4 Off Battery
The battery plant can be disconnected from the UPS, if required for battery maintenance, by opening
the module battery disconnect (MBD) circuit breaker. In this situation the UPS module will continue
to supply conditioned power to the critical load, but if input power fails the UPS system cannot supply
power to the load.
Figure 27 Load on UPS, battery not available
2.3.5 Emergency Module Off
The Local Emergency Module Off (LEMO) mode will transfer the critical load to the bypass line and
remove power from all UPS module components except the controls, bypass circuit breaker and the
static switch.
The Emergency Module Off control is a guarded pad next to the display touchscreen (Figure 2).
Lift the cover and press the pad. The load will be transferred to bypass, and the battery (MBD), input
and output circuit breakers will be opened (tripped). Refer to 2.5 - Shutdown Procedures.
Figure 28 Emergency modules off
!
CAUTION
When the UPS system is operating with the module battery disconnect (MBD) circuit
breaker(s) open, the critical load is not protected from loss of the utility source power.
Bypass
Input
Battery
System
DC Bus
Module
Output
BFB
CB2 CB1
MBD
Bypass
Battery
System
DC Bus
Module
Output
BFB
CB2 CB1
MBD
Input