Replacing a power supply

Use these instructions to install a power supply in the Flex System Carrier-Grade chassis. You can install a power supply while the Flex System Carrier-Grade chassis is powered on.

Statement 31

DANGER

Electrical current from power, telephone, and communication cables is hazardous.

To avoid a shock hazard:

• Do not connect or disconnect any cables or perform installation, maintenance, or reconfiguration of this product during an electrical storm.
• Connect all power cords to a properly wired and grounded power source.
• Connect to properly wired power sources any equipment that will be attached to this product.
• When possible, use one hand only to connect or disconnect signal cables.
• Never turn on any equipment when there is evidence of fire, water, or structural damage.
• Disconnect the attached ac power cords, dc power sources, network connections, telecommunications systems, and serial cables before you open the device covers, unless you are instructed otherwise in the installation and configuration procedures.
• Connect and disconnect cables as described in the following table when you install, move, or open covers on this product or attached devices.

To Connect:

To Disconnect:

Turn OFF all power sources and equipment that is to be attached to this product. Attach signal cables to the product. Attach power cords to the product. For ac systems, use appliance inlets. For dc systems, ensure correct polarity of -48 V dc connections: RTN is + and -48 V dc is -. Earth ground should use a two-hole lug for safety. Attach signal cables to other devices. Connect power cords to their sources. Turn ON all the power sources.

Turn OFF all power sources and equipment that is to be attached to this product. For ac systems, remove all power cords from the chassis power receptacles or interrupt power at the ac power distribution unit. For dc systems, disconnect dc power sources at the breaker panel or by turning off the power source. Then, remove the dc cables. Remove the signal cables from the connectors. Remove all cables from the devices.

Statement 34

CAUTION:

To reduce the risk of electric shock or energy hazards:

• This equipment must be installed by trained service personnel in a restricted-access location, as defined by the NEC and IEC 60950-1, First Edition, The Standard for Safety of Information Technology Equipment.
• Connect the equipment to a properly grounded safety extra low voltage (SELV) source. A SELV source is a secondary circuit that is designed so that normal and single fault conditions do not cause the voltages to exceed a safe level (60 V direct current).
• Incorporate a readily available approved and rated disconnect device in the field wiring.
• See the specifications in the product documentation for the required circuit-breaker rating for branch circuit overcurrent protection.
• Use copper wire conductors only. See the specifications in the product documentation for the required wire size.
• See the specifications in the product documentation for the required torque values for the wiring-terminal screws.

Attention: The following circuit breaker and ground cable ratings apply to -48 V dc power supplies only:

Breaker	Listed 70 A	See Note 1
Ground cable	4 AWG with Listed lug which can accept M6 ground screws	See Note 2
Torque rating for ground screws	4.0 - 4.8 Newton-meters (35.4 - 42.5 inch-pounds)	-
The maximum steady state current of the -48 V dc power supply is less then 70 A. However during specific events, such as over subscription, it is possible for the power supply to briefly draw a current greater than 70 A. Therefore it is recommended that the power supply be protected by a Listed circuit breaker that will support up to 90 A for a minimum of 20 ms. The suggested Telect High Current Panel Dual 350A Power Distribution Panel (part number 350CB06) using the Telect 70 A circuit breakers (Part number 090-0052-0070) conforms to this specification. If not connecting to a SELV source which provides Reinforced insulation you must use a Ground Cable.

Important:

• Do not mix different types of power supplies in the Flex System Carrier-Grade chassis.
• Each chassis must contain either all dc-powered supplies or all ac-powered supplies.
• Make sure that the power cord is not connected to the power supply when you install the power supply in the chassis.
• Do not remove the plastic strain-relief ties from the rear of the power supply.

To install a power supply, complete the following steps.

1. If you are adding a power supply, remove the filler from the power-supply bay in which you want to install the power supply (press the release tab, grasp the filler by the slot, and pull it out of the bay).
2. Grasp the power-supply handle and slide the power supply into the bay until it locks in place.
3. If you are installing a -48 to -60 V dc power supply, connect the earth ground cable to the power supply.
   1. Use a 10 mm nut driver to remove the hex nuts from the ground studs.
   2. Remove the lock washer and one of the flat washers from each ground stud.
   3. Push the ground lug onto the ground studs; then, place the flat washer, the lock washer, and the hex nut back on each ground stud.
   4. Use a 10 mm nut driver to tighten the hex nuts to 4.0 - 4.8 Newton-meters (35.4 - 42.5 inch-pounds).

   
   
   
4. Connect the power cord to the power supply:
   1. Loosen the strain-relief ties that are attached to the power-supply handle, but do not remove them.
   2. Align the power cord with the power-supply handle; then, secure the cord to the handle with the strain-relief ties.
      
      
   3. Loop the power cord connector around and connect it to the power supply.
      
      
   4. Push the power cord back through the strain-relief ties to remove excess cable from the loop.