Distribution Switching Devices and Equipment

Revised: January 2019
  • Energized load break elbows on Kuhlman submersible transformers shall not be used to isolate or drop load unless the transformer has a yellow plastic sign on top stating “OK to switch.” For more information see Standards Bulletin #180 and T&D Guideline #4-20-12.0. If the transformer cannot be identified in the field, ECD shall attempt to verify the type of transformer before switching is ordered
  • Non-load break underground elbow shall not be used to drop load
  • Load break elbows shall not be used to make or separate ties between two different substations

If the overhead equipment does not have an additional load side disconnect switch, disregard references to the load side disconnect switch(es) in the following switching procedure.

Switching Underground Switchgear:

  1. Verify that the location and the number of the vault or UG switch matches the switching order or the Energy Control System Operator instructions.
  2. Unlock and open the switch cabinet and visually inspect the condition of the cabinet and switch(es). (Refer to District T & D Guideline 4-20-10.2 for information regarding “Missing Arc Compressor Covers in S & C Padmounted Switch Cabinets”)
  3. Visually verify the switch(es) position and the barrier board location. (The barrier board shall only be placed between the switch(es) when a clearance is in place, all other times the barrier board should be hanging in front of the switch blades providing a barrier from the exposed conductors.)
  4. After ECC gives permission to operate the switch(es), make sure no one is standing in front of the open bay doors or close the bay doors before operating the switch(es). You shall wear your rubber gloves or provide another form of insulation (i.e., rubber blanket to stand on) before operating the switch(es).
  5. Operate the switch(es) as instructed by ECC.
  6. After you have operated the switch(es), visually inspect the contacts to verify that the switch(es) functioned correctly.

To Disable Reclosing on Line Recloser

The District has two basic types of line reclosers; hydraulic and electronic.
The hydraulic reclosers may be manually or electrically controlled.

When requesting a Hot Line Hold on a 12kV circuit, all source side reclose device(s) shall be placed on Hot Line Hold.

For this process refer to Tagging Procedures, Hot Line Hold section.

To Remove a Line Recloser from Service

The following procedures describe basic switching orders for the overhead and underground distribution systems. These procedures can be modified to fit particular circumstances.

Step 1: Employee

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

Step 2: System Operator

  • Reviews the request and verifies the exact location of the work
  • Orders the bypass switches closed
  • Orders the source and load disconnect switches to be opened, if applicable
  • Orders recloser tagged with Abnormal Condition Card

    The line side of the recloser may have solid connections. A crew will need to open the line side jumpers of the recloser if a clearance is requested.

Step 3: Employee

  • Closes the recloser’s by-pass switches and opens the recloser’s source and load side disconnect switches
  • Tags recloser with Abnormal Condition card
  • Verifies with the System Operator that the line recloser is out of service

To Isolate a Line Sectionalizer

The following procedures describe basic switching orders for the overhead and underground distribution systems. These procedures can be modified to fit particular circumstances.

For certain switching conditions, (trap run, cold load pick up, etc.) the System Operator may request that the sectionalizer be by-passed.

Step 1: Employee

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

Step 2: System Operator

  • Reviews the request and verifies the exact location of the work
  • Orders the employee to close the by-pass switch(es) and open the sectionalizer
  • Orders source and load connections opened
  • Orders the sectionalizer to be tagged with an Abnormal Condition Card

The sectionalizer may have solid connections. A crew will be needed to disconnect the sectionalizer.

Step 3: Employee

  • Closes the sectionalizer’s by-pass switch(es) and opens the sectionalizer
  • Opens the sectionalizer’s source and load connections and tags with an Abnormal Condition card
  • Notifies the System Operator that the sectionalizer has been bypassed, and that the source and load connections are opened and tagged

To Isolate an Auto-Booster/Regulator

Do not by-pass an auto booster/regulator unless the tapchanger is verified to be in the NEUTRAL position and the controller is in MANUAL or OFF.

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

For certain switching conditions, (trap run, etc.) the System Operator may request that the equipment be by-passed.

Along with regulators, auto-boosters shall be operated correctly to avoid injury or catastrophic failure. They shall be on neutral prior to being bypassed. Auto-boosters are single-phase, rated at 10%, four-step voltage control devices (four steps to raise voltage 10%).

Step 1: Employee

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

Step 2: System Operator

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

Step 3: Employee

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

If the neutral position cannot be verified, orders will be issued to drop load by opening autobooster/regulator source and load side disconnect switch(es) (if load break rated) or at the next up stream load break device.

DO NOT CLOSE THE AUTOBOOSTERS/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 auto-booster/regulator to service, reverse above steps as ordered by the System Operator.

De-energizing a three-phase Distribution line that could have a capacitor on-line

Overhead lines

All lines can be safely de-energized at any location by using:

  • All three-phase gang operated devices
  • All single-phase devices rated to break load, such as a single phase recloser or sectionalizer
  • All single blade line switches when a load buster tool is used

Exception:

The District has a small number of capacitors that have been installed off the main three-phase line. All of these capacitors have 100 amp fuses protecting the line between the main line and the capacitor.
The fuses can be safely opened with a load buster tool to de-energize the line without taking the capacitor off first.

Underground lines

All lines can be safely de-energized at any location by using:

  • All three-phase gang operated devices
  • All underground padmount capacitors are identified on the underground prints. When a three-phase section of line needs to be de-energized and is feeding an underground capacitor the capacitor shall be taken off-line first, unless the outage is from the gang operated device. The capacitor can be taken off-line by pushing a button on the inside of the enclosure or by pulling the yellow operating handle on the side of the unit. When completed, all other switching can be done

Distribution SCADA Switches or Recloser Procedures

The following procedures describe basic switching guidelines for SCADA-controlled switches and recloser. These procedures can be modified to fit particular circumstances.

Normal Operations

System Operator is in control of the distribution SCADA equipment in the same manner as SCADA-controlled equipment inside the substation.

Outage Operations

Patrol

  • The System Operator will dispatch Qualified Employee(s) to patrol when a protective device has relayed to lockout.
  • When a Qualified Employee(s)’s patrol brings them to a SCADA-controlled switching device they shall communicate to System Operator whether the line is clear from the source to that point.
    • If the line is clear from the as-operated substation source to the SCADA-controlled switching device (apparatus), the System Operator may perform remote switching to energize the patrolled section of line.
    • If the line is not clear and can be resolved without a clearance, the Qualified Employee(s) may place any SCADA-controlled switching devices into LOCAL mode prior to removing object from line
      • During normal working hours the Qualified Employee(s) that placed SCADA-controlled distribution devices into LOCAL shall place them back into REMOTE control.

Taking a Clearance

  • To take a clearance beyond a SCADA-controlled switching device, Qualified Employee(s) shall open the appropriate switching devices to provide the required visible open points for a clearance. When taking a clearance on a SCADA-controlled switching device(s), open the clearance-side disconnects for the visual open point and leave the non-clearance-side disconnects closed to maintain voltage for the battery charger.
    • Qualified Employee(s) shall place the SCADA-controlled switching device(s) used for the clearance into LOCAL mode.
  • The Qualified Employee(s) may put additional SCADA-controlled distribution SCADA switching devices located upstream or downstream of the clearance into LOCAL mode for additional safety precautions.

Releasing a Clearance

  • Qualified Employee(s) shall close the appropriate disconnects.
  • All devices put into LOCAL mode during the clearance shall be returned to REMOTE and/or Normal settings after clearance is released as directed by System Operator. The System Operator shall operate the SCADA-controlled switching devices to return to normal after the clearance is released.
  • During normal working hours the Qualified Employee(s) that placed SCADA-controlled distribution devices upstream or downstream of the clearance into LOCAL for additional safety precautions shall place them back into REMOTE control.

Distribution SCADA Control Failure

  • Dispatch Qualified Employee(s) to investigate and if necessary, notify additional departments for resolution.