Substation Switching Procedures

The following procedures describe basic switching guidelines for taking substations out of service. These procedures can be modified to fit particular circumstances.

General Instructions to Clear a Substation to the Feeder Getaway Switches.

These instructions assume there is a standard type of circuit switcher, and Notes indicate differences if there is no circuit switcher or if it is a “post” type such as S&C series 2030.

Note: Stations equipped with circuit switchers for bank high-side protection, use SF6 gas for the arc-breaking medium. There are gas “targets” which indicate the absence of gas. These “targets” are found on the “bottle” of the circuit switcher. The switch or circuit switcher shall NOT be operated when a “target” is found. The System Operator shall be notified immediately. If you are not certain that the circuit switcher SF6 gas target is OK, do not operate the circuit switcher and contact the Energy Control Center, immediately.

Follow these steps to clear a station with a bank circuit switcher.

Step 1: Employee

  • Submits a completed Switching Request to the Energy Control Center (See Section A)

Step 2: System Operator

  • Verifies the request and prepares the switching order
  • Works with the employee to transfer the substation load
  • Remotely opens the circuit breakers via SCADA. As the breakers are opened, takes note of SCADA to verify zero amperage

Step 3: Employee

  • Works with the System Operator to verify that the breakers are open
  • Checks the SF6 gas target(s) on the circuit switcher(s)

Step 4: System Operator

  • Opens the circuit switcher(s) via SCADA. Most circuit switchers have motor operated disconnects which shall have the linkage decoupled, locked open, and tagged with a Master Safety Card

    If the station does not have a circuit switcher, or has a “post” type circuit switcher, the high-side switch shall be manually opened, locked, and tagged. If the substation is fed from transmission circuit breaker(s), the circuit breaker(s) should be opened first to de-energize the transformer

Step 5: Employee

  • Verifies with the System Operator that the circuit switcher (or other high-side switch if appropriate) has opened via SCADA. Decouples the linkage, locks open, and tags
  • Checks the SF6 gas target(s) on the circuit switcher(s)

Step 6: System Operator

  • If the clearance extends to the feeder getaway switches, the System Operator shall order disconnects open and tagged
  • Another clearance option would be to open, rack out, and tag the circuit breakers

Step 7: Employee

  • Opens the feeder getaway switches and tags. Or, for metal clad stations, racks out and tags the circuit breakers

Step 8: System Operator

  • Issues the clearance

Step 9: Employee

  • Receives clearance and proceeds to Verify, Test and Ground, as applicable
  • Proceeds with and completes the work
  • Restores the system within the clearance to the original status or informs the System Operator of any addition or changes to the system or its operation. (This does not include the clearance points)
  • Clears temporary station service backfeed(s), if applicable
  • Releases the clearance and notifies the System Operator that they removed their personal grounds and all personnel and equipment are in the clear

Step 10: System Operator

  • Verifies 12 kV circuit breakers are open
  • Orders the card(s) removed
  • Orders low-side bank switch(es) closed, as appropriate
  • Closes the circuit switcher(s) via SCADA

If the substation is fed from transmission circuit breaker(s), the circuit breaker(s) should be the last device closed to energize the station.

  • Orders feeder getaway switches closed

Step 11: Employee

  • Closes low-side bank switch(es), as appropriate
  • Removes the card(s) and verifies the SF6 gas target(s) on the circuit switcher(s)
  • Unlocks, and re-couples the linkage before the System Operator can close the circuit switcher via SCADA

If there is no circuit switcher or a “post” type circuit switcher, closes and verifies all three phases of the high-side switch.

  • Closes feeder getaway switches to the open circuit breakers

Step 12: System Operator

  • Initiates switching procedure to restore load to the station
  • Closes the circuit breakers via SCADA and verifies that each breaker indicates closed and shows load

Step 13: Employee

  • Verifies the circuit breakers closed
  • Restores the Load Tapchanger (LTC) or regulator to automatic
  • Station back to normal

Hot Line Hold: Before operating distribution voltage circuit breakers or transfer bus switches, the affected circuit(s) shall be placed in Hot Line Hold mode.

Remote Racking: At stations where remote racking has been installed, the remote racking equipment shall be used whenever racking circuit breakers into or out of an energized bus.