User manual

10-1
Power Supplies 10
dc Power Supplies
Thedcpowersupplysystemallowsthe4400tobeinstalledinatelephonecompany
environmentwiththe necessary dcpowerinput being furnished bythe 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
floatingandcaneitherbeconnectedtohousegroundortheappropriatedcreturn.
Anadditionalcasegroundscrewisalsoonthepoweradapterbox.Thisconnection
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
Return
Chassis
+48 Vdc (Return)
-48 Vdc
Chassis Ground
Safety
Plastic Door
Terminal Block
junction box for 48 Vdc
power supply