Telephone Systems Efficiency Co. Inc.


The SEI PoweRack 300

The PR300-U is an enhanced version of the PoweRack 300R. This a premises powering unit that integrates NT1 caging, 48 volt DC power, and battery backup in a single unit for powering ISDN telephones and Lucent B-300 NT1's or equivalents. The PR300-U is available in four models that house and power 12 to 48 NT1's and provide power for 24 to 96 phones in a multipoint mode. In addition, the 24 and 72 line versions of the PR300 are field upgradeable by adding a 300R-U NT1 cage. The PoweRack 300-U can be either wall or rack mounted. The small footprint and simple installation of the PR300-U allows a cost-effective installation without the requirement for punchdown blocks (an optional wiring harness is available to facilitate NT1 input cabling). Battery holdover can be increased by adding external battery packs. During extended periods of utility outage the batteries are protected from over-discharge by the built-in low voltage detector and disconnect circuit. Remote monitoring is provided by a contact closure that can be interfaced to a remote alarm unit.

All PR series units are mountable either on a wall or on 19" racks.  Mounting brackets for 23" or 25" racks may be ordered as options (specify 23RM or 25RM after the model number).

Ordering Information

Model # Description Dimensions
(W" x D" x H")
PR300-24-U PoweRack with 1 NT1 card cage
and 2.5 AmpHr battery (2 hour holdover)
19 x 6 x 12
PR300-48-U PoweRack with 2 NT1 card cages 
and 2.5 AmpHr battery (1 hour holdover)
19 x 6 x 17
PR300-72-U PoweRack with 3 NT1 card cages 
and 8 AmpHr battery (2 hour holdover)
19 x 6 x 30
PR300-96-U PoweRack with 4 NT1 card cages
and 8 AmpHr battery (1 hour holdover)
19 x 6 x 35


RA Remote alarm unit 2.5 x 4 x 1
300R-U Additional twelve position NT1 rack 19 x 5 x 5.25
BP2 Additional 2.5 AmpHr battery pack (for the PR300-24-U and PR300-48-U) 19 x 5 x 7
BP8 Additional 8 AmpHr battery pack (for the PR300-72-U and PR300-96-U) 19 x 5 x 7
NT1B-300 Lucent B-300 NT1 with multipoint capability
G-B300 Lucent-compatible NT1 sub-assembled in USA with multipoint capability 

Technical Specifications

Electrical Environmental
Universal Input (90-265 VAC)
Frequency 47-440 Hz
Output Voltage 42-56 VDC
Operating 0 deg C to +50 deg C
Storage -25 deg C to +60 deg C
Humidity 95% non-condensing

Optimum battery life will be achieved if the unit is operated at a temperature of 25 deg C.
NT1 Compatibility Standards
Lucent NT1B-300 UL 1012

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