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What is a Load Operator
A qualified electrical worker that acts as a PIC for an assigned portion of power system-has been assigned both O/R and O/A
What is a PIC
Holds O/A and O/R for an assigned portion of the power system
Where can details of operator duties be found
What equipment is deemed distribution equipment
All PSSP equipment from high-side disconnect switch of substation main transformer downstream to the distribution customer and all equipment in radially fed substations
Who holds O/R and O/A for distribution equipment
Load Operator desks
How are Operating Authority boundaries between Load Desks and Generation, IPPs and Customers with hazardous infeeds defined
Through jointly signed Operating Orders
How are AORs divided
Into geographic areas distributed between 10 desks
Where are Load Desk AORs defined
What should a Load Operator always reference prior to switching in a substation?
The Station Local Operating Order
Describe the “5 R’s” of switching.
- Readings: take readings of affected equipment (max demands of all 3 phases)
- Ratings: determine the ratings of affected equipment
- Reclosing: turn off reclosing
- Reactors: reactor impedance in each branch must be considered to determine loop impedance
- Regulators: neutral/control off (NCO)
What is a low-side or low-voltage tie?
- -A low-voltage tie refers to the low-voltage side of the step down transformer, where bus work is tied together, effectively creating a loop through the transformers to the high voltage side
- -This can result in transformer and feeder overloads
What are the two general types of isolation points? Give examples of each type.
- Disconnect Switches
- Circuit Switcher
- Racked Out Circuit Breaker
- Temporary Line Cuts: (Fixed, non-operable component)
- Section of bus
- Flying Taps
- Drop Leads
What must be done to an isolation point in order for it to be used in support of a Safety Protection Guarantee?
Enforced with a ‘Do Not Operate’ Tag (Clearance, Test&Work, Guarantee of Isolation)
True or False – Voltage Transformer secondaries are Level 5 equipment and therefore, when located inside a Clearance zone, should be opened and tagged Self Protection to prevent backfeed prior to going to work.
- The PIC will 'reach in' to establish isolation as required
Why are gas relays opened and tagged Caution when isolating a substation power transformer?
Gas Trip Relays are opened and tagged as part of SPG so that they do not inadvertently operate while working on the equipment
How is a transfer bus used to maintain service to a feeder position that is coming out of service?
The associated feeder’s load can be tied off to the bus-tie or standby position through the transfer bus
Describe how series reactors can affect load sharing when paralleling feeders.
- -Series reactors significantly affect load sharing if their impedances differ
- -Reactor impedance in each branch must be considered to determine the current shared in each branch
- -This current must not exceed the maximum capability of the associated switch
Where is the criteria listed for D3 switching
involving series reactors?
The theory behind the calculations required to determine the maximum currents a D3 switch can interrupt is explained
Define feeder cable.
- -The underground portion of a feeder that delivers power from the substation potheads to the first switchable device in the field
- -Feeder cable is part of a circuit’s main trunk
Where is the isolation of a feeder cable typically mimicked?
Mimicked in AREVA and POCC
How do cablemen request for station risers to be removed in advance of planned feeder cable work?
- When submitting the outage request form through CROW:
- ‘Comments’ box under ‘Notifications’ will read ‘Remove Stn Risers’
How is the removal of station risers mimicked?
- In AREVA, the Station Pothead symbol for a circuit is a selectable point that can be toggled
- green = risers removed
- black = risers installed
What is ferroresonance?
- A phenomenon that can occur on electric circuits that contain capacitance (underground cable) in series with nonlinear saturable inductance (Transformer, Voltage Reg.)
- Results in nonlinear overvoltages (high harmonic) and can lead to equipment damage and failure
- Excessive voltage can appear across open phases
- Most likely to occur during a switching event (with one(or two) of the phases open)
Where is the feeder cable switching procedure to be followed by Load Operators found?
System OO 2T-27
What must be done prior to opening pothead sleeves on a feeder cable and why?
- Confirm current to be less than 2 Amps
- This ensures that load will not be dropped or a parallel broken on the sleeve
What is a standby circuit?
- -A dedicated circuit that remains energized and will be available if needed to carry the full load of any feeder it provides service to
- -Multiple feeders could be carried at once if loading permits
- -The standby can be tied to in the field through a normally open switch
How can maximum demand readings be used to help make operational decisions?
- Max. Demand Readings – (one of the 5 R’s)
- Maximum observed loads for a particular circuit are considered to determine that equipment ratings and relay settings will not be exceeded.
How can a feeder’s kVA report be used to help make operational decisions?
- The operator can take the %kVa that is connected beyond any switch and multiply it by the feeder’s Max. Demand to approximate how much load is connected beyond that switch
- This allows the operator to open/close switches with confidence that equipment ratings will not be exceeded.
What operating prints are currently used in the
Control Centre to operate and mimic the URD system?
UDDs – Underground Distribution Diagrams
DODs – Distribution Operating Diagrams
Underground Distribution Schematics
Describe a URD loop system?
Loop – Fed URD (Level 4)
A system designed to include multiple feeds to provide an alternate source for the URD primary
What is the normal procedure for switching on a URD loop system?
- The field must call the Control Centre for direction.
- Level 4 equipment, where there is more than one source of hazardous energy, requires an SPG(Clearance, T&W)
- The PIC will issue switching steps to the field
- *The only exception is for cable fault troubleshooting. The Field may switch Level IV URD under a LiveLine*
- **Parallels are not normally made**
What factors must be considered when closing a loop on the URD system and why?
- Single phase URD:
- -the sources of either side of a normally open may not be the same phase
- -a ‘break’ before ‘make’ policy(with a short outage) is used to eliminate a phase to phase fault when switching
- Three phase URD:
- -when making parallel (closing a loop) the operator must consider the magnitude of the loop current that could flow
- -loop current could be high enough to blow fuses and overload equipment
- -fuses may need to be replaced with solid links
- -Possibility of incorrect phasing?
Where is the Communication Protocol to be followed by the PIC and field worker found?
The Safety Practice Regulations (SPRs) and System Operating Order 1T-13
What is a Designated Isolation Point? Where would a DIP be recorded?
- Designated Isolation Points (DIP) are used where equipotential grounding is not practicable at the worksite.
- This DIP will be under worker control by placing a Grounding/Blocking Tag immediately upon receiving an SPG.
- If a DIP is required by the field, it must be agreed to during the issuing of the SPG and must be recorded on both the BCH Control Center and field worker’s SPG forms
What fundamental questions must be answered by the field worker when returning an SPG to the PIC?
The SPG holder is responsible for telling the PIC the status of the equipment that was worked on by declaring whether or not it is “Ready for Service” and whether or not “Worker Protection Grounding/ Bonding” is removed. Also, whether or not station risers are removed and if phasing is required.
What are the PIC’s responsibilities following the return of an SPG declared “Not Ready for Service”?
- -The PIC will check the appropriate box on the Returned eSPG and write notes on the eSPG indicating the reason for the “Not Ready for Service” condition.
- -When a new eSPG is issued to return the equipment to service, the PIC will inform the receiver of the “Not Ready for Service” state.
- -The Returned eSPG (the original eSPG) is then promoted to the Completed state as soon as the new eSPG is issued.
What are the PIC’s responsibilities following
the return of an SPG with “Worker Protection Grounds Applied”?
- -The PIC will check the appropriate box on the Returned eSPG and write any required / relevant notes on the eSPG.
- -The PIC will then place a removable Field Ground device symbol within the isolated zone or on at least one of the devices associated with the isolated zone and tag it with a GROUNDED tag
- -The eSPG will be kept in the Returned eSPG section.
What is the purpose of a CNE?
- A Commissioning Notice to Energize (CNE) is required to energize new equipment.
- The CNE authorizes the Operating Authority to proceed with the initial system energization tests of electric system plant additions, modifications, and replacements.
What is a Plant Alteration?
- -The addition or removal of high-voltage (less than 60 kV) plant on the distribution system.
- -All changes to the distribution system, which impact the operating records, require a PA.
What part of the power system requires a PA for the addition and removal of plant?
- It covers the distribution primary from the feeder-cable terminations and overhead feeder connections in the substation outward.
- Basically, any equipment outside the station fence
What is the purpose of the PA process and what operating order is the process defined in?
-To track the progress of a PA from the time it is issued through the time it is completed and the new drawings have been updated, approved, and issued.
What is PAT?
The Plant Alteration Tracking (PAT) system is the computer program used to track the progress of a PA from the time it is issued through the time it is completed
What is the role of the PA Coordinator?
- -The PA Coordinator is responsible for managing the PAT tool
- -The PA Coordinator will print a hard copy of the electronic PA(PDF) and attach a PA cover sheet to it.
- -This will form the PA package and will be filed in the PA filing cabinets in the control room.
- -The PA Coordinator will proofread for errors and accuracy before the PA reaches a Load Desk
When working on a PA to install a new underground loop connection, at what point is a Safety Protection Guarantee required?
- “Installation of the new cable between two existing portions of the electrical system requires the establishment of a Safety Protection Guarantee (SPG) prior to the termination of the cable at either end that will serve to create a loop on the system.
- The cable becomes a part of the power system when it is terminated even if risers are not installed yet.”
What are the Load Operator’s responsibilities
following the completion of a PA?
- It is the duty of the Load Operator to asses the PA and to determine what operating drawings and operating tools have been impacted.
- It is the responsibility of the Load Operator to ensure all operating drawings and the POCC mimic are updated in real time to reflect the system accurately.
What is a PACTOR?
The commissioning process to be adhered to for all Protection, Control, and Telecommunications equipment for which BC Hydro has asset management
Briefly describe the process for commissioning a brand new field recloser with supervisory control.
- 1. A PA is required to install the new field recloser.
- 2. Field crews will call in and complete the PA to indicate the device is installed.
- 3. Prior to allowing the device to be put in service, the control centre must add the device to the CROW (P3) database and the official mimic display.
- 4. A PACTOR document is then required by the Control Center for upgrading the new manually-controlled device to have supervisory functions.
- 5. The CROW event shall not be completed (closed) until the new supervisory facilities have been commissioned and are available for service.
What is a Declaration of Compatibility?
-A Declaration of Compatibility is provided to the Control Centre when an IPP is becoming commissioned