Substation Voltage Regulators, LTC's and Controls

Substation Voltage Regulators/ LTC’s and Controls

Do not by-pass a regulator unless the tap changer is verified to be in the NEUTRAL position and the controller is in MANUAL or OFF.

Closing the by-pass with the regulator off neutral will result in large amounts of circulating currents that can be hazardous to the employee/worker and may cause catastrophic equipment failure. If the regulator cannot be verified in the NEUTRAL position, report the situation to the System Operator. Further switching shall be done to transfer or drop load as the circumstance warrants.

When switching between substations, follow the procedure in the Substation Switching Procedures Section. After the switching, the station carrying the new load may remain on switching settings, if applicable, until switched to normal. Follow District Conservation Voltage Reduction (CVR) procedures.

To Bypass a Station Regulator

Step 1: Employee/Worker

Step 2: System Operator

  • Reviews the request and verifies the exact location of the work.
  • Orders the regulator placed in neutral and the controller placed in manual or off.
  • Orders the by-pass switch(es) closed and the source and load side disconnect switch(es) opened.
  • Orders the regulator to be tagged with an Abnormal Condition Card, if applicable.

Step 3: Employee/Worker

  • Verifies or places the regulator in the neutral position and the controller in the manual or off position.

    If the neutral position cannot be verified, see next procedure in this section.

    DO NOT CLOSE THE REGULATOR SOURCE OR LOAD DISCONNECTS WITH THE BY-PASS SWITCH(ES) CLOSED WHEN NOT ON NEUTRAL.

  • Closes the by-pass and opens the source and load side disconnect switch(es).
  • Tags the device with an Abnormal Condition Card, if applicable.

To restore regulator to service, reverse above steps as ordered by the System Operator.

To Remove a Station Regulator/LTC NOT on NEUTRAL
Cannot be bypassed and has acceptable voltage.

The following procedures describe steps to remove a regulator/LTC that is NOT in the NEUTRAL position, when the voltage is acceptable.
(Removing a regulator/LTC with unacceptable voltage is covered in the next section.) These procedures can be modified to fit particular circumstances.

NOTE:

Acceptable voltage is usually 120 volts + or - 5%.

Step 1: Employee/Worker

  • Submits a completed Switching Request to ECC (see Section A)

Step 2: System Operator

  • Verifies the request and prepares the switching order
  • Orders the regulator/LTC controller placed on manual or off.

Step 3: Employee/Worker

  • Verifies voltage (usually at the control panel).
  • Places the regulator/LTC controller on manual or off.

Step 4: System Operator

  • Works with employee/worker(s) to transfer the substation load. Verifies the voltage after each circuit breaker is opened. (As the station is off-loaded the voltage on the unregulated station will increase.)

Step 5: Employee/Worker

  • Works with the System Operator to off-load station, arrange for a clearance, installs Master Safety Card(s) and provides station service as needed.

Step 6: System Operator

  • Issues clearance, if applicable.

Step 7: Employee/Worker

  • Receives clearance and proceeds to Verify, Test and Ground, as applicable.
  • Proceeds with and completes the work.
  • Informs the System Operator of the status of any addition or changes to the system or its operation.
  • Clears temporary station service backfeed(s).
  • Releases the clearance and notifies the System Operator that they have removed their personal grounds and all personnel and equipment are in the clear.

Step 8: System Operator

  • Verifies the 12kV circuit breakers and regulator by-pass switches to be in the open position.
  • Orders the 12kV circuit breaker disconnects closed, if applicable.
  • Orders the regulator source and load disconnects closed.
  • Closes the 115kV circuit switcher (or orders the high-side switch(es) closed, if applicable).

Step 9: Employee/Worker

  • Verifies that the regulator/LTC is in the neutral position and controller is in manual or off.
  • Verifies the 12kV circuit breakers and regulator bypass switches are open.
  • Closes the 12kV circuit breaker disconnects.
  • Closes regulator source and load disconnects.
  • Verifies the 115kV circuit switcher has closed (or closes the highside switch, if applicable).

Step 10: System Operator

  • Initiates switching to restore load to the station.
  • Orders the employee/worker to place the controller in the auto position.

Step 11: Employee/Worker

  • Works with the System Operator to transfer load back on the station, adjusting voltage as necessary.
  • Returns the regulator/LTC back to the normal settings.
  • Verifies voltage to insure that the regulator/LTC is working.

Note: The employee/worker on site may request the regulator/LTC to be energized from a remote location.

To Remove a Station Regulator or LTC NOT on NEUTRAL
(Unacceptable Voltage - Emergency Situation)

The following procedures describe steps to remove a regulator/LTC that is NOT in the NEUTRAL position, when the voltage is unacceptable (above 126 or below 114 volts). These procedures can be modified to fit particular circumstances.

Step 1: System Operator

  • Verifies SCADA for an abnormal condition at the station.

Step 2: Employee/Worker

  • Places the regulator or LTC controller on manual or off, if it can be done safely.
  • Verifies the by-pass is open.

Step 3: System Operator

  • Opens circuit breakers via SCADA.

Step 4: Employee/Worker

  • Works with the System Operator to isolate the regulator or LTC for a clearance and places Master Safety Card.
  • Provides station service as needed.

Step 5: System Operator

  • Issues clearance.

Step 6: Employee/Worker

  • 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).
  • Releases the clearance by notifying the System Operator that they removed their personal grounds, and all personnel and equipment are in the clear.

Step 7: System Operator

  • Orders regulator source and load disconnects closed and verify the bypass switches opened (if applicable).
  • Closes the transformer bank circuit switcher (or high-side switch as appropriate).
  • Orders controller placed in automatic position.

Step 8: Employee/Worker

  • Verifies that the regulator or LTC is on neutral and the controller is in manual or off.
  • Verifies the circuit breakers are open, closes the circuit breaker disconnects.
  • Closes regulator source and load disconnects, opens the regulator by-pass switches (if applicable).
  • Places controller in the automatic position.

Step 9: System Operator

  • Transfer load back on to the station.

Step 10: Employee/Worker

  • Restores control power to the regulator or LTC.
  • Works with the System Operator to transfer load back on to the station.
  • Verifies voltage to ensure that the regulator is working. Station normal.