Liebert 350VA to 1000VA Bi-Directional Converter 2.2.2.1 General, Battery Recharge, Overload

2.2.2Bi-Directional Converter 2.2.2.1 General

The Bi-Directional Converter incorporates solid-state devices and control circuitry to convert AC power to regulated DC power for battery charging; and convert DC power from the battery to regulated and conditioned stepped-sinewave AC power for supporting the critical load. The Bi-Directional Converter is a pulse width modulated (PWM) design. The Bi-Directional Converter operates in the following modes:

1.In Normal mode of operation, the Bi-Directional Converter maintains the battery system at a float charge.

2.In Battery mode of operation, the Bi-Directional Converter converts DC power from the battery to regulated and conditioned stepped-sinewave AC power for supporting the critical load.

3.In the recharge mode of operation, the Bi-Directional Converter converts AC power to regulated DC power to recharge the battery.

2.2.2.2Battery Recharge

The UPS contains a battery recharge rate designed to prolong battery life. The battery is constant voltage charged to recharge and maintain the battery in a fully charged state. Recharge time is 6 hours maximum to 90% rated capacity after discharge into full resistive load.

2.2.2.3Bi-Directional Converter DC Protection

The following DC shutdown levels protect the UPS:

DC Overvoltage Shutdown

DC Undervoltage Shutdown (End of Discharge)

DC Undervoltage Warning (Low Battery Reserve)

2.2.2.4Output Protection

For output faults including short circuits and overloads, the UPS is protected by the input circuit protector during Normal mode and by electronic current limiting during Battery mode.

2.2.2.5Overload

The UPS is capable of supplying power for overloads exceeding 100% and up to 110% of full load rating, continuously. A visual indicator and audible alarm indicate overload operation. For greater current demands, the UPS employs circuit protector and electronic current-limiting protection to prevent damage to components. The UPS is self-protecting against any magnitude of connected output overload. The UPS control logic senses and disconnects the UPS from the critical AC load and clears the protective circuit breaker during Normal mode.

2.2.2.6Output Frequency

An oscillator controls the output frequency of the UPS. The oscillator maintains the output frequency to + 0.5 Hz of nominal when not synchronized to the utility/mains source.

2.2.2.7Battery Over-Discharge Protection

To prevent battery damage due to excessive discharge levels, the UPS control logic automatically monitors the battery voltage and load level and switches off the output at the predetermined battery shutdown voltage set point.

PowerSure PSA	6	Guide Specification
350 – 1000VA		SL-23271 8/03