Emerson Liebert APS Installation Manual download pdf (Page 30)

22 Chapter 3 Operating Procedures

Liebert APM Modular UPS User & Installation Manual

Battery start button

Figure 3-2 Location of battery start button

3.3 Procedures Of Transfer Between Operation Modes

3.3.1 Transfer From Normal Mode To Battery Mode

Open the input switch to cut off the mains input, and the UPS enters battery mode. To return to normal mode, wait a

few seconds and close the input switch to connect the mains power to the UPS. The rectifiers will restart

automatically after 10 seconds and resume feeding power to the inverters.

3.3.2 Transfer From Normal Mode To Bypass Mode

Press and hold the INVERTER OFF key for two seconds to transfer the UPS to bypass mode.

Note

In bypass mode, the load is being powered by the mains input and is not receiving conditioned power through the inverters.

3.3.3 Transfer From Bypass Mode To Normal Mode

In bypass mode, press and hold the INVERTER ON key for two seconds. When the inverters are ready, the UPS

transfers to normal mode.

3.3.4 Transfer From Normal Mode To Maintenance Bypass Mode

When the UPS is operating in normal mode, use the following procedures to transfer the load from the inverter output

to the maintenance bypass.

Caution

Before performing this operation, read the messages on the LCD to be sure that bypass supply is normal and the inverters are

synchronous with it. If these conditions are not present, there is a risk of a short interruption in powering the load.

1. Press and hold the INVERTER OFF key on the right side of the operator control and display panel for two seconds.

The inverter indicator turns off, the status indicator turns yellow and an audible alarm sounds. The load is transferred

to the static bypass and the inverters turn off.

Note

Pressing the SILENCE ON/OFF key cancels the audible alarm, but leaves the warning message displayed until the appropriate

condition is rectified.

2. Close the maintenance bypass switch. The load is now on maintenance bypass.

Warning

If a module needs repair, wait about 10 minutes for the internal DC bus capacitors to discharge before removing the faulty module.

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Emerson Liebert APS Installation Manual Page 30