Vertiv™ |
Liebert® EXM™ UPS 20-100kVA, 50/60Hz User Manual |
42
Load on Inverter
Operating in Load on Inverter Mode, the Liebert
®
EXM’s rectifier derives power from a utility AC source and
supplies regulated DC power to the inverter, which regenerates precise AC power to supply the connected
equipment. The rectifier also uses the utility source power to charge the batteries.
Load on Battery Mode—Requires Optional External Battery Cabinet
When utility AC power fails, the Liebert
®
EXM protects the critical load by instantaneously channeling battery
power from optional External Battery Cabinets to the inverter, which continues supporting the critical load
without interruption. When utility power returns and is within acceptable limits, the Liebert
®
EXM automatically
shifts back to Load on Inverter Mode, with the rectifier powering the critical load.
Auto-Restart Mode
The battery may become exhausted following an extended AC utility failure. The inverter shuts down when the
battery reaches the End of Discharge voltage (EOD). The UPS may be programmed to “Auto Recovery after
EOD” after a delay time if the AC utility recovers. This mode and any delay time may be programmed by the
commissioning engineer.
ECO Mode (Single-Module UPS System Only)
When ECO mode is selected, the Liebert
®
EXM switches inverter power from the UPS input to the bypass input
to save energy by improving UPS efficiency. In this mode, the bypass is the preferred source. If the bypass
voltage or frequency becomes outside preset limits, the UPS load is transferred back to the inverter.
Load on Bypass Mode
When the Liebert
®
EXM is operating in Load on Bypass Mode, the load is directly supported by utility power and
is without battery backup protection.
The Liebert
®
EXM’s static transfer switch will shift the load from the inverter to Load on Bypass Mode without
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 user
Module Redundancy Mode
When the Liebert
®
EXM is in module redundancy mode, the load percentage is calculated using the available
power module capacity or nameplate rating capacity, whichever capacity is lower.
Module redundancy mode can be set at the factory or by the user. A maximum of one module can be set for
redundancy. Availability of this feature depends on module capacity of the frame. Refer to the UPS control
manual, SL-26200, for instructions on setting this feature. The manual is available at Vertiv’s Web site,
www.vertiv.com
Example 1
•
Four 50kVA power modules installed
•
Nameplate rating capacity = 150kVA
•
One power module in redundant mode
•
Configured capacity = 150kVA
•
Load = 150kVA
Load percentage will be calculated based on nameplate rating capacity = 150kVA capacity. In the event of a single
power module fault, the system will signal a Loss of Redundancy Alarm and a Power Hardware Mismatch and
continue in double-conversion mode and provide up to 150kVA capacity.
Summary of Contents for Liebert EXM
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