
1 -48 Volts: This terminal screw connects to a -48 Volt DC power source.
2 Return: This terminal screw connects to the power source return.
3 Ground: This terminal screw connects the card to the chassis ground.
4 Power: This green LED indicator is ON when -48 VDC power is being supplied to the unit.
5 3 Amp GMT Fuse: These two fuses (F1 and F2) protect the 1251 card from input power shorts.
TRANSPORT
®
POWER
MAINT
PWR
3 Amp
GMT
1251
TRANSPORT
®
CARD
-48
RTN
GND
1 2 3 4 55
General
The 1251 Power Maintenance Card is designed to provide temporary
power to a 1555 APC chassis during shelf maintenance periods which
involve the removal or replacement of the Power and Alarm card.
Caution: The 1251 card is not mechanically or electrically com-
patible with the Power and Alarm card slot. Do not insert this card
into Slot 1.
The 1251 front panel contains a screw terminal strip with 3 connectors,
two GMT type power fuses, a power LED indicator, and two card-
retaining thumb screws.
Design Features
• The card may be installed in any vacant 1557 APC card slot.
• The card is compatible with any 1555 APC chassis.
• The card provides fused input protection and a power indicator.
Operation
Refer to the front panel diagram above and to the simplified circuit dia-
gram below for the following operational features.
An external -48 VDC fused source is fed into the card from the front
panel screw terminal strip. This power is then fed through front panel
card fuses F1 and F2 (GMT type, 3 Amps). The power is then fed to
both the A and B power bus pins of the card connector. Both A and B
feeds are diode protected from power reversals.
The front panel power indicator is diode biased to allow the LED to be
on only when the proper polarity of -VDC is wired to the front panel
terminal connections.
Specifications
Mechanical
Dimensions: 10.5" H, 1" W, and 11" D
Weight: approximately 10 ounces
Environmental
Operating Temp: 0° to 50° C(32° to 122°F)
Storage Temp: -20° to 85° C(-4° to 185°F)
Humidity: 95% max (non-condensing)
Part Number
F-1251-001--11
Chassis Ground
Return (B)
-48 VDC (B)
Return (A)
-48 VDC (A)
Fuse F2
Ground
Return
-48 VDC
Simplified Circuit Diagram
Power
Card
Fuse F1
Power
Terminal
Diode
Isolation
Connector
Power/Polarity
ON Indicator
1251 Power Maintenance Card
Configuration Guide
Part Number 45-00062
Rev 1.00
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