Nokia 7750 SR - Connecting to DC Power

Installation
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7750 SR ESA 100G Chassis Installation Guide
Release 20.5
3HE 16094 AAAA TQZZA Issue: 01
4.3 Connecting to DC Power
The 7750 SR ESA 100G supports –48 VDC source power.
Step 1. Verify that the external DC power feed is between -39 VDC and -72 VDC,
and protected with a circuit breaker.
Step 2. Verify that the external DC power feed designated for the PSU is turned off.
Step 3. Prepare DC ground and input power wires (not supplied), see Figure 9.
Step 4. Plug the DC power cable connector (supplied) into the PSU.
Danger: Before connecting power to the chassis or wiring the DC connector, ensure that
power to the feed lines is turned off at the supply circuit breaker or disconnected from the
power bus.
Warning:
• The DC model variants should be installed only in restricted access areas (such as
dedicated equipment rooms and electrical closets) in accordance with Articles 110-26
and 110-27 of the most recent National Electrical Code ANSI/NFPA 70.
• The plug-in DC power supply must be between -39 VDC and -72 VDC, and protected
with a circuit breaker.
• To provide adequate circuit protection between the DC power supply and the chassis,
all intermediate wiring and circuitry should be rated to carry a load at least two times
the maximum rating for this chassis.
• The 7750 SR ESA 100G is capable of operating -39 VDC to -72 VDC at 37 A maximum
current level.
• The wiring between the DC power supply and the chassis must be stranded copper
wire within the range of 16 to 20 AWG in accordance with local electrical codes.
Note:
• An additional chassis ground point is located below the DC power entry block for
attaching a DC power chassis ground if required by local electrical codes. The ground
point must be connected with an M4 screw and a terminal lug as specified by local
electrical codes.
• If a single power feed (either A or B) is connected to provide power to the system, it
supplies power to both of the PSUs if two modules are plugged in. The DC power
feeds, A and B, are internally bridged using a diode.