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POWERING TECHNOLOGY

Manual No. MS0027-MAN rev. 4

guardian_access_3u_ms27-man-rev4-0817.indd

2.3.2.1 Low Voltage Disconnect (LVD) and Dummy LVD

Generally, the system is equipped with low voltage battery disconnection, which prevents

the batteries from deep discharging, thus prolonging the battery life. A disconnection

requires a detected mains failure at the supervision unit.

If disconnection occurs, the batteries will not supply power to the load until they have

been recharged to set voltage level, which can be adjusted by the user.

If disconnection occurs, the batteries will be reconnected when mains supply returns.

A dummy LVD can also be installed into the power system if the Low Voltage

Disconnection function is not needed.

2.3.2.2 Partial Load Disconnection / Load Shedding (PLD)

Partial load disconnection can be congured to be voltage or time dependent, this is

selected when ordering the power system.

At a mains outage the controller will open the PLD contactor when the batteries have

discharged to a certain voltage or if the battery voltage has been under a certain voltage

for a predetermined time. The disconnection has to be set according to the present load

and battery manufacturer’s discharge tables or requirements.

2.3.3 Rectier Module

The fan-cooled rectier converts the AC input to -48VDC output for loads and batteries.

It is designed for parallel operation and plug-in installation in the power shelf and supplies

extremely stable DC power.

Each rectier incorporates an internal microprocessor that sends frequent updates to the

system controller and adjacent rectiers. This ensures accurately controlled load sharing

among rectiers and supplies status and identication information to the controller.

The rectier module features two LEDs for status indication, thermal protection with

power derating, and input over voltage disconnection with automatic reset. The rectier

module is hot-swappable and can be quickly removed and replaced without disrupting

the system or load.

Handles

Cooling Fans

Status LEDs

Figure 2-5 Guardian Rectier

Unipower Guardian Access 3U User Manual

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