10. Secure each power cable lug to the terminal studs, first with the split washer, then with the nut. Apply
between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut (see Figure 152 on page 419).
Do not overtighten the nut. (Use a 7/16-in. (11 mm) torque-controlled driver or socket wrench.)
a. Attach the positive (+) DC source power cable lug to the RTN (return) terminal.
b. Attach the negative (–) DC source power cable lug to the –48V (input) terminal.
CAUTION: Ensure that each power cable lug seats flush against the surface of
the terminal block as you are tightening the nuts. Ensure that each nut is properly
threaded onto the terminal stud. The nut should be able to spin freely with your
fingers when it is first placed onto the terminal stud. Applying installation torque
to the nut when improperly threaded may result in damage to the terminal stud.
CAUTION: The maximum torque rating of the terminal studs on the DC power
supply is 58 lb-in. (6.5 Nm). The terminal studs may be damaged if excessive
torque is applied. Use only a torque-controlled driver or socket wrench to tighten
nuts on the DC power supply terminal studs.
CAUTION: You must ensure that power connections maintain the proper
polarity. The power source cables might be labeled (+) and (–) to indicate their
polarity. There is no standard color coding for DC power cables. The color coding
used by the external DC power source at your site determines the color coding
for the leads on the power cables that attach to the terminal studs on each
power supply.
NOTE: The DC power supplies in slots PEM0 and PEM1 must be powered by dedicated
power feeds derived from feed A, and the DC power supplies in PEM2 and PEM3 must
be powered by dedicated power feeds derived from feed B. This configuration provides
the commonly deployed A/B feed redundancy for the system. For information about
connecting to DC power sources, see “Electrical Specifications for the MX960 DC Power
Supply” on page 225.
11. Loosen the captive screw on the cable restraint on the lower edge of the power supply faceplate.
12. Route the positive and negative DC power cables through the left and right sides of the cable restraint.
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