Charge timers

DOE-SPEC-3021-97

specified float charge voltage. Following a prolonged discharge of

the battery (see paragraph 3.3.3.6, below), the output voltage shall

provide the option of automatically switching to the battery

manufacturer's specified equalize charge voltage for a period of time

set by the timer specified in paragraph 3.3.3.6, below or continue

charging at the predetermined float level.

Charge timers. The rectifier/charger shall be equipped with two

3.3.3.6

automatic equalization charge timers to control the output voltage.

Timer 1 shall be a fixed two-minute timer that prevents application of

an equalization charge if the ac input power loss is less than two

minutes. Timer 2 shall be an adjustable timer that can be selected

from 0 to 72 hours in increments of 1 hour. This timer shall initiate

and control the length of the equalization charge. At the end of the

equalization charge time the charger shall automatically revert to

float charge. [Also provide manual equalization capability.]

Temperature compensation. The rectifier/charger shall be equipped

3.3.3.7

with temperature compensation controls to limit current drawn by

the battery string dependent on the battery cell(s) skin temperature.

3.3.3.8

Filtering. The rectifier/charger shall limit ac ripple voltage on the dc

bus to 5% maximum of the rated ac input voltage.

3.3.3.9

Recovery control. The rectifier/charger shall include circuits and

controls to recover gradually, following a loss of ac input power.

This "walk in" circuit shall control the dc output from 0-100% of

normal operation over a period of less than 60 seconds. The output

voltage shall be increased gradually until it reaches the required

charge voltage or current limiting takes place.

3.3.4

Battery power supply. In the event that the battery is disconnected for

maintenance, the UPS shall continue to operate in a power-conditioning mode

and the output characteristics of the UPS shall not be degraded. Upon failure of

the normal source for the UPS system, the load shall continue to receive power

from the dc system, which shall have the following characteristics:

ATTENTION:

The following information concerning the backup battery must be obtained from the DOE Standard "Sealed

Valve-Regulated Lead-Acid Storage Batteries" or "Flooded-Type Lead-Acid Storage Batteries." Remember - the

short-circuit current capability of a sealed, valve-regulated battery is higher than the same size flooded-cell

battery. If a new battery system is purchased with the UPS system, items b. through e. may be provided by the

battery manufacturer at a later date.

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]

a. Battery Type:

[

b. Nominal Voltage,

Ungrounded:

[

] [To be provided by battery

manufacturer]