Bypass Mode; Battery Mode; Maintenance Bypass - Emerson Liebert NXL series Operation And Maintenance Manual

Liebert NXL UPS
1.2.2

Bypass Mode

When the Liebert NXL is in bypass mode, the load is directly supported by
utility power and is without battery backup protection.
The Liebert NXL's inverter and bypass static switch will shift the load from the
inverter to bypass mode without an interruption in AC power if the inverter is
synchronous with the bypass and any of the following occurs:
• Inverter fails
• Inverter overload capacity is exceeded
• Inverter is manually turned off by the user
NOTE:
If the inverter is asynchronous with the bypass, the static switch will transfer the
load from the inverter to the bypass WITH interruption in AC power to the critical
load. This interruption will be less than 20ms. This interruption time may be
modify through Bypass Transfer Setpoint Menu (for Service only).
1.2.3

Battery Mode

When utility AC power fails, the Liebert NXL protects the critical load by
instantaneously channelling battery power to the inverter, which continues
supporting the critical load without interruption.
When utility power returns and is within acceptable limits, the Liebert NXL
automatically shifts back to Normal mode, with the rectifier powering the
critical load.
1.2.4

Maintenance Bypass

The installation of a Maintenance Bypass Cabinet or Assembly is recommended
to allow you to totally isolate the UPS from all power sources. Use of the
Maintenance Bypass is described in 2.0 - Operation.
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Operation and Maintenance Manual 250-300-400-800kVA