Emerson 7400 user manual Isolator on both modules, Following points will be live within the UPS

Series 7400 Single Phase 1+N UPS

How to turn OFF the System but continue to provide

Load power through the Maintenance Bypass

This procedure should be followed if one-plus-oneis to be powered-down while continuing to supply load through the maintenance bypass line. Note that during this procedure the load will be unprotected against mains supply disturbances once the inverter(s) has been switched off.

Step Action Response

1.Ensure that LS3 is illuminated on the mimic panels (indicating that the static bypass supply is healthy).

2.Press the Inverter OFF switch (S6) on both modules

3. Close the Maintenance Bypass

Isolator on both modules.

4.Open the Output Isolator on both modules.

5.On each module - Open the battery circuit breaker followed by the input Isolator (and Static Bypass Isolator if separate. For 110V systems Static bypass isolator is mounted in auxiliary cubicles).

6.Isolate the UPS input supply from the mains distribution panel to make the UPS safe for work to be carried out internally.

Mimic panel LEDs LS4 and LS6 should extinguish on both modules and LS5 should illuminate to show that the load has been transferred to the static bypass line.

Note: On a redundant system both Inverter OFF switches (S6) must be operated before LS5 illuminates but in a non-redundant system the Inverter OFF switch must be pressed on one module only before LS5 illuminates. However, as the load is transferred to the static bypass, the second module should be turned OFF also.

Mimic panel LEDs - No change

Mimic panel LED LS5 should extinguish on both modules.

All the operator panel led indications and messages should extinguish as the mains driven internal power supplies decay.

WARNING

The following points will be live within the UPS:

-Bypass supply input terminals

-Maintenance Bypass Isolator switch

-Static Bypass Isolator Switch (if fitted)

-UPS output terminals

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