Emerson 400V Manuel D’Utilisation

This procedure must be followed to completely power down the UPS and LOAD. All power switches, 

isolators and circuit breakers will be opened and power will be removed from the load.
In multi-module systems – perform each step of the procedure in every UPS module before proceeding 

to the next step.

1. Press the EPO (Emergency Power Off) button at the UPS front panel only. This will disable 

Rectifier, Inverter, Static Switch and Battery operation. The Load will be de-energised.

2. Open the UPS door to gain access to the main power switches.
3. Open the Rectifier input power switch Q1
4. Open external battery circuit breaker (where an external battery is used). This breaker is located 

inside the battery cabinet (if used) or is otherwise adjacent to the battery racks 

5. Open Output power switch Q5
6. Open bypass input power switch Q2
7. Ensure maintenance bypass power switch Q3 is open.
8. All mimic panel LED indications and messages will extinguish as the mains driven internal 

power supplies decay.

9. To completely isolate the UPS from the AC supplies, the main external power input isolator (both 

isolators, where split supplies are provided for rectifier and bypass) and external output isolator 

must be opened and tagged with warning labels accordingly.

This circuit has been designed to switch off the UPS in emergency conditions (i.e., fire, flood, etc.). The 

system will turn off the rectifier, inverter and stop powering the load immediately (including the 

inverter and bypass), and the battery stops charging or discharging.
If the input utility is present, the UPS’s controls will remain active; however, the output will be 

turned off. To remove all power from the UPS, the external feeder breaker should be opened.

The following procedure will switch off all power to the load equipment.

NOTE
Except in an emergency situation, do not press any remote EPO button.

Hazardous Battery Voltage
No operator serviceable parts are located behind covers that require a tool for their removal. 
Only qualified service personnel are authorised to remove such covers.
The UPS battery and connecting terminals remains energized at hazardous voltage levels at 

all times. The battery is located behind protective covers that require a tool for their removal: 

inside the UPS cabinet (30 and 40kVA models), inside a free-standing battery cabinet or on 

open racks inside a dedicated battery room that may be locked.