Emerson Liebert APS Installation Manual download pdf (Page 26)

18 Chapter 2 Operation

Liebert APM Modular UPS User & Installation Manual

interruption is programmable but typically set to be less than 3/4 of an electrical cycle, for example, less than 15ms

(50Hz) or less than 12.5ms (60Hz).

2.2.5 Maintenance Bypass Mode

If UPS maintenance or repaired is needed, you may use the manual maintenance bypass switch to transfer to the

load to the maintenance bypass, with no interruption in power to the load.

Warning: risk after load transfer to maintenance bypass

After the UPS is transferred to maintenance bypass, the power modules and bypass module are inoperative and the LCD has no

display, only the green indicator of the input surege protective device (SPD) shows the UPS has mains input, but the output

terminals corresponding to closed output distribution switches and the neutral bars are energized.

2.2.6 ECO Mode

IF economical (ECO) mode is selected, the double-conversion UPS operation is inhibited at most times for the

purpose of saving energy. In this mode of operation, the bypass is the preferred source, and only when the voltage

and frequency of the bypass supply are outside specifications will the load be transferred to the inverters. This

transfer takes place with an interruption of less than 3/4 of an electrical cycle, for example, less than 15ms (50Hz) or

less than 12.5ms (60Hz).

2.3 Battery Management

2.3.1 Normal Function

The following functions are configured by the commissioning engineer through dedicated configuration software.

1. Constant current boost charge

The charge current can be set.

2. Constant voltage boost charge

The boost charge voltage can be set as required by the type of battery.

For valve regulated lead acid (VRLA) batteries, the maximum boost charge voltage should not exceed 2.4V/cell.

3. Float charge

The float charge voltage can be set as required by the type of battery.

For VRLA batteries, the float charge voltage should be between 2.2V and 2.3V.

4. Float charge temperature compensation (optional)

The temperature compensation coefficient can be as required by the type of battery.

5. EOD protection

When the battery voltage drops to the EOD voltage, the battery converter will shut down automatically and the battery

is isolated to avoid further battery discharge. The EOD voltage is settable from 1.6V/cell to 1.75V/cell (VRLA) or

0.9V/cell to 1.1V/cell (NiCd).

6. Battery low warning time

The setting range is between 3 minutes and 60 minutes. The default setting is 5 minutes.

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Emerson Liebert APS Installation Manual Page 26