61212073L1-5D
Issue 4, August 2004
3
Figure 2. NIU3 Circuit Diagram
Figure 3. NIU3 3-Slot Shelf Rear Panel
Power
Fully populated, the NIU3 3-Slot Shelf operates on
local –48 VDC at 0.375 amps maximum, or ±24 VDC
at .750 amps maximum. The shelf backplane has spade
lug terminal connections (
TB1
) for both an “A-side”
and “B-side” independent DC source, plus Frame
Ground (see
Figure 4. Local DC Power Connection
WARNING
Ensure power is off and tagged out-of-service
before making power wiring connections.
Use one of the following requirements for powering the
unit locally:
1. Connect to a grounded
−
48 VDC source, electri-
cally isolated from the AC source. Provide branch
circuit overcurrent protection with a fuse or circuit
breaker, minimum 48 VDC, maximum 15 amps.
Provide an easily accessed approved and rated
disconnect device in the field wiring.
2. Connect to an approved Class 2 Type (LPS) power
supply rated 48 VDC, maximum 240 VA.
For those slots not populated with an NIU3 circuit card,
blank covers (P/N 1212076L1) must be installed.
The following terminal connections are made:
1. Connect –48 V or ±24 V local supply to
PWR A
.
2. Connect the associated return wire to
RET A
.
3. If redundant power is intended, make similar
connections to
PWR B
and
RET B
.
CAUTION
Terminate grounds to an approved ground
location. Check metal-to-metal contact on all
ground connections. Verify ground circuit
continuity.
4. Connect the common frame ground terminal or
ground lug (6 AWG max.) to an approved ground
location.
CAUTION
Per GR-1089-CORE, October 2002, Section 9,
this system is designed and intended for
installation in a DC-C (common) bonding and
grounding system only. It is not intended or
designed for installation in a DC-I (isolated)
bonding and grounding system.
Independent Power Supply
An optional independent power supply unit is available.
The Power Supply/Rectifier (PS/R), P/N 1212080L1,
provides –54V at 2 A. The PS/R plugs into a standard
SLOT 2
SLOT 3
P7
P8
P4
P3
COM NC NO
DC POWER
SLOT 1
PWR
B
RET
B
RET
A
PWR
A
P2
P1
48V
, 375MA / 24V
, 750MA
USE COPPER CONDUCTORS ONLY.
CERT.TO CAN/CSA STD.
C22.E NO.225-950
CONF TO ANSI/UL
STD 1950
IN
NIU3
1212073L2
OUT
CUST
NTWK
3
IN
OUT
CUST
NTWK
2
IN
OUT
CUST
NTWK
1
THIS UNIT MAY BE POWERED
BY MULTIPLE SOURCES.
DISCONNECT ALL SOURCES
PRIOR TO SERVICING.
REFER TO INSTALLATION
INSTRUCTIONS BEFORE
CONNECTING POWER.
PWR
B
RET
B
RET
A
PWR
A
B
Supply
B
Return
Frame
Ground
A
Return
A
Supply
TB1
