Connecting a 300 W DC Power Supply to the Source Voltage

Two 300 W DC power supplies are available: model 10933 (front-to-back airflow) and model 10944 (back-to-front airflow). Both can connect to either a +24 V or a –48 V power source.

The connection instructions, starting at step 4, are different depending upon whether you are connecting to a +24 V power source or a –48 V power source.

The DC power connection at your facility must be made by a qualified electrician, following these instructions.

Warning

Warning

Always make sure that the DC circuit is de-energized before connecting or disconnecting the DC power cables on the DC power supply.
Caution

Caution

Provide proper connection and strain relief on the DC power cables in accordance with all local and national electrical codes.
  1. Verify that the DC circuit is de-energized.
  2. Attach an ESD-preventive wrist strap to your bare wrist and connect the metal end to an appropriate ground point on the rack.
  3. Slide the cover off the terminal block.
  4. Connect the DC power input cables as follows:
    When connecting the power supply to a +24 V source:
    1. On each terminal, loosen the screw enough to allow the spade terminal to slide underneath the captive square washer.
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      Loosening Terminal Screws (Connecting to a +24 V Source)
      ../Graphics/Sh_210_DC_connect_1a.svg
    2. Slide the spade terminal of the negative wire (–24 V) under the captive square washer on the negative terminal (labeled –24 V).
    3. Slide the spade terminal of the positive wire (+24 V) under the captive square washer on the positive terminal (+24 V).
    4. Tighten both screws on the terminal block to 11 in‑lb (1.25 N m).
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      Tightening Terminal Screws (Connecting to a +24 V Source)
      ../Graphics/Sh_211_DC_connect_2_24V.svg
    When connecting the power supply to a –48 V source:
    1. On each terminal, loosen the screw enough to allow the spade terminal to slide underneath the captive square washer.
      Click to expand in new window
      Loosening Terminal Screws (Connecting to a –48 V Source)
      ../Graphics/Sh_210_DC_connect_1.svg
    2. Slide the spade terminal of the negative wire (–48 V) under the captive square washer on the negative terminal (labeled –48 V).
    3. Slide the spade terminal of the positive wire (–48 V RTN) under the captive square washer on the positive terminal (labeled RTN).
    4. Tighten both screws on the terminal block to 11 in‑lb (1.25 N m).
      Click to expand in new window
      Tightening Terminal Screws (Connecting to a –48 V Source)
      ../Graphics/Sh_211_DC_connect_2.svg
  5. Slide the cover into place over the terminal block.
  6. Connect the cables to the DC source voltage, using hardware appropriate to the installation site and following local and national electrical codes.
  7. Energize the DC circuit.

Leave the ESD strap permanently connected to the rack, so that the strap is always available when you need to handle ESD-sensitive components.

You can now connect network interface cables to the switch, using the instructions in Connecting Network Interface Cables.