Specifications

The system battery shall be sized to provide the specified back-up time to the

inverter when the UPS is supplying 100% rated load. The battery shall be of the

VRLA, Flooded Lead Acid or Nickel Cadmium types.

3.8.1. VRLA Battery System Example (EXAMPLE using 375 kVA UPS)

a. The battery system shall include a DC cable landing box equipped with a

1000A/600Vdc breaker. The landing box shall interface the UPS’ DC input

to battery cabinets.

b. Each battery cabinet shall include a 400A/600Vdc breaker to facilitate

isolation of one or more string for maintenance purposes.

c. The battery shall be capable of operating in an average ambient temperature

of 25 °C, with excursions of 16 °C to 32 °C and shall be sized as follows:

1. float voltage: 540 VDC

(2.25 to 2.27 V/cell)

2. final voltage: 400 VDC

(1. 67V/cell)

4. FUNCTIONAL DESCRIPTION

4.1. Rectifier

4.1.1. General

The Rectifier shall convert the incoming AC power into regulated DC power

to supply the inverter input and system battery. The front end shall be a

simple 3-phase diode bridge. AC reactor and capacitor shall filter the Rectifier

input.

4.1.2. Reflected Harmonic Content

The Rectifier shall not produce more than a maximum of 6% reflected current

distortion into the Rectifier input utility source when nominal voltage and

rated load is applied. Typically, the amount of reflected current distortion

shall not exceed 9% THD at 50 % load.