Emerson NX manual Load Transfer and Retransfer-Single Module System, Transfer Procedure

Operation

2.5.3Load Transfer and Retransfer-Single Module System

Changing the load from the UPS system to the UPS bypass is called a transfer. Changing the load from UPS bypass to the UPS system is called a retransfer. Note that the UPS system control logic can initiate automatic load transfers and retransfers. Refer to 2.6 - Automatic Operations.

Transfer Procedure

1.Press the “Stop Inverter” menu button on the touchscreen.

2.The load will transfer to Bypass mode and Inverter will turn Off.

Retransfer Procedure

1.Press the “Start Inverter” menu button on the touchscreen.

2.The Inverter will synchronize with the bypass and transfer the load to Normal mode.

2.5.4Maintenance Bypass Load Transfers-Single Module System: If Load is on UPS Bypass

Follow these instructions to manually transfer the load between the Maintenance Bypass and the UPS bypass line. Do not transfer the load between the Maintenance Bypass and the UPS module (inverter) output. Use the Monitor/Mimic Display screen to verify that the UPS bypass line is available.

NOTICE

Risk of improper operation. Can cause equipment damage.

Failing to follow the proper sequence when operating any circuit breaker may cause damage to the connected equipment. Operating a Maintenance Bypass circuit breaker out of sequence could cut Off power to the critical load.

NOTICE

Risk of improper operation. Can cause equipment damage.

The UPS system must be on internal bypass before the following procedures are performed or the MIB or the MBB is operated. Doing so may damage to the UPS and the critical load may be lost.

1.Transfer the UPS system to bypass (see 2.5.3 - Load Transfer and Retransfer-Single Module System). The “OK to transfer” lamp on the key-release unit will light.

NOTE

If the maintenance bypass cabinet or switchboard has any other type of custom interlock, follow the specific instructions for that interlock system to remove the key.

2.If using a key interlock system:

a. Depress the key-release unit push button, turn the key and remove from key-release unit.

NOTE

The UPS system is now locked in bypass and cannot be retransferred to the inverter until the key is reinserted.

b. Insert the key into the lock for the Maintenance Bypass Breaker (MBB); retract the bolt.

3.Close the Maintenance Bypass Breaker (MBB).

NOTICE

Risk of improper operation sequence. May cause equipment damage.

Failure to close the Maintenance Bypass Breaker (MBB) will interrupt power to the load.

4.Open the Maintenance Isolation Breaker (MIB). The UPS system is now isolated from the critical load and the load is now on Maintenance Bypass.

5.If using a key interlock system,

a.Remove the key from the lock for the Maintenance Isolation Breaker (MIB).

b.Put the key back in the solenoid.

6.If UPS bypass shutdown is required, open the Bypass Input Breaker (BIB). This breaker is external to the UPS; it may be in the Maintenance Bypass Cabinet.

Liebert®NX™ 20