Connecting the chassis to power

Power is supplied to the Flex System Carrier-Grade chassis when one end of each power cord is connected to a power connector on the rear of the chassis and the other end of each power cord is connected to a power source. The Flex System Carrier-Grade chassis dc-power inputs are configured for dc isolated return (DC-I). The dc RETURN (RTN) terminal or conductor is not connected to the equipment frame or the grounding means of the equipment.

Connecting for N+N power redundancy

The Flex System Carrier-Grade chassis can have up to six power supplies. The chassis allows you to populate power supplies to meet the load demand that is installed in the chassis. As more nodes are installed in the chassis, you can install additional power supplies to meet the increased load demand.

Attention: If there is not enough power available from the power supplies to meet the load demand installed in the chassis, the Chassis Management Module will not allow some of the devices to power on.

To provide power source redundancy for the chassis, you can connect the power supplies in an N+N configuration, where N can be 1, 2 , or 3, depending on the total load installed in the chassis. In this configuration, the power-supply power cords are connected to separate sources. If a supply circuit fails, the remaining power supplies have enough power available to power the entire chassis load. A fully configured chassis with N+N power redundancy has six power supplies.


Illustration showing N+N power redundancy

Connecting for N+1 power redundancy

If power source redundancy is not a concern but you want power supply redundancy, you can connect the power supplies in an N+1 configuration, where N can be 1, 2, 3, 4, or 5 depending on the total load that is installed in the chassis. In this configuration, the power-supply power cords are connected to the same source but there is one extra power supply available (+1). If one of the power supplies fails, the remaining power supplies have enough power available to power the entire chassis load. If two or more power supplies fail, it is possible for the entire chassis to lose power. If the power source circuit fails, the entire chassis will lose power.


Illustration showing N+1 power redundancy
Note: The Flex System Carrier-Grade chassis does not have a power switch. See Disconnecting the chassis from power for more information.

Statement 29


Graphic illustrating Safety Statement 29
CAUTION:
This equipment is designed to permit the connection of the earthed conductor of the dc supply circuit to the earthing conductor at the equipment. If this connection is made, all of the following conditions must be met:

Statement 31



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

To avoid a shock hazard:

To Connect: To Disconnect:
  1. Turn OFF all power sources and equipment that is to be attached to this product.
  2. Attach signal cables to the product.
  3. 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.
  4. Attach signal cables to other devices.
  5. Connect power cords to their sources.
  6. Turn ON all the power sources.
  1. 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.
  2. Remove the signal cables from the connectors.
  3. Remove all cables from the devices.

Statement 34



CAUTION:
To reduce the risk of electric shock or energy hazards:
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) -
  1. 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.
  2. If not connecting to a SELV source which provides Reinforced insulation you must use a Ground Cable.

To connect the chassis to power, complete the following steps:

  1. For dc-powered chassis:
    1. For a chassis powered by -48 to -60 V dc power supplies (restricted-access location is required), connect an earth ground cable to each 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).

      Illustration showing how to attach the ground cable
    2. Connect each power cord from the dc power supplies to a dc power distribution panel (PDP) (restricted-access location is not required).
      Attention:
      • Do not route the power cords over removable modules or allow the cords to interfere with the module handles.
      • In North America, connect the power cords to a UL-listed PDP only.
  2. For an ac-powered chassis (restricted-access location is not required), connect each power cord from the power supplies to a power distribution unit (PDU), uninterruptible power source (UPS) or wall receptacle. AC power is supplied to the Flex System Carrier-Grade chassis by one of the following options:
    1. A power cord that connects to a PDU or UPS supplying a maximum 20 A branch circuit protection.
    2. A power cord that connects to a wall receptacle supplying a maximum 20 A branch circuit protection.
    3. A special use Flex System 3X Power Cord that connects to a wall receptacle supplying a maximum 32 A branch circuit protection.
    Attention: Do not route the power cords over removable modules or allow the cords to interfere with the module handles.
  3. Make sure that the following LEDs are lit:
    • The logo on the chassis front information panel.
    • The dc power in or ac power in and dc power out LEDs on each power supply.
    • The power LED on each I/O module.
    Note: The power LED on each compute node and on the Flex System Manager management node, if one is installed, flashes slowly to indicate that the node is connected to power and is ready to be turned on.
  4. If the LEDs are not lit:
    1. Disconnect the chassis from the power source.
    2. Reseat all of the components in the chassis.
    3. Reconnect the chassis to the power source.
    4. If the problem persists, contact Support.