Toshiba – Toshiba 1500 SERIES User Manual

Page 18

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TOSHIBA

5.0

Operating the UPS

5.1

Operation Modes

5.1.1

AC Input Mode (normal operation)

Power flow in AC input mode

The above illustration shows circuit power flow in the ac input mode. The UPS

unit's rectifier, included in a boost chopper circuit, converts ac input power to dc

power. This dc power runs the unit's transistor inverter and charges the batteries.

The boost chopper circuit maintains a constant voltage, with current limiting, for

charging the batteries and assures proper sine waveform generation for the

output current. The unit's batteries are maintained in a constantly charged state

when the UPS is in the normal operation mode. On the front panel, LED's labeled

"On Line" and "AC Input" should be on and the "Fault" LED should be off

(See Section 9.2 Panel Layout).

5.1.2

Battery Backup Mode

Power flow in battery backup mode

The above illustration shows circuit power flow in battery backup mode. When

commercial ac power failures occur, the UPS's batteries instantly begin supplying

dc voltage to the UPS's main inverter circuit. This circuit changes (inverts) the dc

power into ac power. The ac power is available at the unit's output receptacles.

This back-up process will continue until the UPS's battery voltage drops below a

specific minimum level. When this occurs, the batteries will stop supplying power

to the load. This minimum level is the rated minimum voltage (Vmin). The rated

battery voltage chart in section 5.6 (See Section 5.7 for battery backup time)

shows (Vmin). On the front panel, LED's labeled AC Input and Fault should be

off. The On Line and Backup LEDs should be on (See Section 9.2 Panel

Layout).

5 - 1

UPS batteries

Bypass circuit

UPS

main

circuit

UPS

receptacles

(rear panel)

= power flow

5-15P

5-15R

Power

input plug

Fuse

Transformer

(Plus Series)