Nortel Networks Passport 4400 - Manual (Page 105)

10-1
Power Supplies
10
dc Power Supplies
The dc power supply system allows the 4400 to be installed in a telephone company
environment with the necessary dc power input being furnished by the telephone
company to the input of the 4400.
The -48 volts dc version of the 4400 power supply system is identical to the ac
version except for the addition of a terminal power adapter that plugs into the
line cord Electronic Industry Association (EIA) jack on back of the unit. The five
power supplies stack identically to the AC version. The connectors accept the
same cables for input and output power.
The dc input voltage must be within the range of -32 volts dc and
72 volts dc. The plus (+) and minus (-) markings on the input power adapter box
indicate the polarity of corresponding battery connections. They are electrically
floating and can either be connected to house ground or the appropriate dc return.
An additional case ground screw is also on the power adapter box. This connection
must be grounded to the chassis safety ground for safety and electrical noise
suppression. Do not operate the unit without the ground screw connected to the
safety ground.
Figure 10-1. dc Power Supply
E
D
C
B
A
-48 +48 Retur
n
Chassis
+48 Vdc (Return)
-48 Vdc
Chassis Ground
Safety
Plastic Door
Terminal Block
junction box for 48 Vdc
power supply