Specifications

Issue 6 February 2007 407
The DC power relay protects the batteries from over discharging.
EMI filters
The Electromagnetic interference (EMI) filters suppress noise voltage on the AC input line to the
MCC1 cabinet.
Ring generator
The ring generator converts the -48 VDC input to a 67-VAC to 100-VAC, 20-Hz or 25-Hz ringing
voltage. The analog line circuit packs use this AC voltage output to ring telephones. The AC
outputs are routed from the ring generator to port carriers, expansion control carriers, and
control carriers.
Fuses
20-A fuses protect the power in each cable that goes from the AC power distribution unit to
power converters in the carriers.
The following figure shows AC power distribution in some MCC1s. The DC power distribution
cables are on both sides of the cabinet. These cables supply power to each of the carriers. The
optional battery charger is at the right side of the power distribution unit.
Figure 87: AC power distribution in MCC1 cabinets
Power backup
If AC power fails, three 48-VDC batteries power the system for:
● 10 seconds in a PPN cabinet
● 15 seconds in an EPN cabinet
● 10 minutes in the control carrier of a standard reliability system
● 5 minutes in a control carrier of a high reliability or critical reliability system
● 10 minutes in the expansion control carrier in the A position of an EPN cabinet
3
"D" position
carrier
Battery
charger
(optional)
"E" Position
Carrier
Power
distribution
unit
lcdfacpd RPY 053097