ADC 70 - Manual (Page 10)

ADCP-80-524 • Issue 1 • November 2001
Page 10
©
2001, ADC Telecommunications, Inc.
1.1 Power Buses
Each
fuse panel has two separate power buses (feeds). Each bus distributes the input power to
the
output power circuits. In each bus circuit, current flows from the input power bus, through
the
fuse, to the output power circuit. A typical fuse panel block diagram is shown in
Figure 7 .
The
current capacity of each bus of the traditional power fuse panel is 65 Amps maximum. The
output
fusing of the traditional fuse panel should not exceed 65 Amps per bus. This provides a
total
capacity of 130 Amps per panel. The maximum current per bus is marked on the fuse
panel.
The
current capacity of each bus of the uninterrupted power fuse panel is 60 Amps maximum.
However,
the output fusing of the uninterrupted fuse panel should not exceed 30 Amps per bus.
This
provides a total capacity of 60 Amps per panel. The maximum current per bus is marked
on
the fuse panel.
Each
of the feed buses has a capacity of eight fuse positions. Other fuse capacity configurations
may
be available by special order. When a fuse fails, the input power bus is disconnected from
the
corresponding output circuit. This causes the alarm LED for the bus to light and also opens
or
closes the alarm relay contacts (form C contacts).
1.2 Redundant Power (Uninterrupted Power Fuse Panel)
The
uninterrupted power fuse panel provides redundant power to fused equipment through the
use
of Schottky steering diodes. When power to one bus is interrupted, the Schottky steering
diodes
enable the other bus to supply power to the entire fuse panel and to maintain output
power
for both buses (bus A and bus B). If bus A loses power, bus B will support the power load
of
bus A while maintaining its original power load. Likewise, if bus B loses power, bus A will
support
the power load of bus B while maintaining its original power load.
1.3 Input Voltage
The
fuse panel can accommodate either –24 Vdc on both buses or –48 Vdc on both buses. The
voltage
level is sensed by the fuse panel circuitry. The input voltage used with the fuse panel can
have
the following characteristics:
• –24
Vdc nominal, within range of –21 Vdc to –30 Vdc
• –48
Vdc nominal, within range of –42 Vdc to –56 Vdc
Fuse
panels for use with other input voltage and polarity power may be available by special
order.