What should a Load Operator always reference prior to switching in a substation?
Station Operating Order
Describe the “5 R’s” of switching
Readings
Ratings
Reclosers
Reactors
Regulators
What is a low-side or low-voltage tie?
Low side ties are higher Voltage circuits that are normally tied together directly, tied together through Lower Voltage ties.
What are the two general types of isolation points? Give examples of each type. (1T-09)
There are two types of isolation points; conventional and temporary linecuts. Examples of conventional isolation points are a cut-out and a disconnectswitch. A temporary line cut is normally a fixed, non-operable component suchas a riser or a section of bus that has been removed or securely tied back toprovide visible separation
What must be done to an isolation point in order for it to be used in support of aSafety Protection Guarantee?
Isolation point must be tagged with a Do Not Operate tag (T+W, CL, GOI)
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.
False
Why are gas relays opened and tagged Caution when isolating a substation powertransformer?
Gas relays are opened so that they do not inadvertently open whenworking on the equipment.
How is a transfer bus used to maintain service to a feeder position that is comingout of service?
An energised transfer bus maintains service to a feeder by theassociated D3 being closed, energising the feeder.
Describe how series reactors can affect load sharing when paralleling feeders.
Series reactors having different impedances can affect load sharing whenparalleling feeders because the current that will run through each branch willbe different. This could cause the current to be exceed the currentinterruption capability of the switch
Where is the criteria listed for D3 switching involving series reactors?
2T-27
Define feeder cable
A feeder cable is the underground portion of a feeder that deliverspower from the substation to the first switchable device in the field
Where is the isolation of a feeder cable typically mimicked?
AREVA and POCC
How do cable men request for station risers to be removed in advance of planned feeder cable work?
Cable men can request the station risers to be removed in advance but entering “Remove STN risers” is the comments box, under the notification heading in CROW.
How is the removal of station risers mimicked?
Removal of the station risers is mimicked in AREVA but toggling the station potheadsymbol to green which means that risers are removed.
What is ferro-resonance?
Ferro-resonance can occur on an electric circuit that contains capacitance in series with nonlinear saturable inductance. This can create over voltages with high harmonic content that can damage equipment and hurt people
Where is the feeder cable switching procedure to be followed by Load Operators found?
2T-27
What must be done prior to opening pothead sleeves on a feeder cable and why?
It must be confirmed that current is less than 2 amps to ensure that load is dropped or a parallel is not broken on the sleeve.
What is a standby circuit?
A dedicated circuit which normally has no load on it and will be available to carry the full load of any of the feeders it provides standby too.
How can a standby and partial standby circuits be identified on AREVA and POCC?
A true standby circuit is shown buy having a solid red box around the feeder name in AREVA and POCC. A partial standby circuit has a dashed red box around the feeder name in AREVA and POCC.
How can maximum demand readings be used to help make operational decisions?
Max demand readings are used to determine if a circuit has sufficient room to carry additional load during peak times.
How can a feeder’s kVA report be used to help make operational decisions?
A feeders KVA report can be used to determine how much a load a certain part of the feeder is carrying. This can allow confidence that equipment ratings will not be exceeded while opening and closing switches.
What operating prints are currently used in the Control Centre to operate and mimic the URD system?
UDD, UDS or DOD depending on the portion of the province.
Describe a URD loop system?
A URD loop system has multiple feeds to provide an alternate source for the URD primary. The is achieved by the use of NO points to ensure equipment is only fed from one source at a given time.
What is the normal procedure for switching on a URD loop system?
“Break” before “Make”
What factors must be considered when closing a loop on the URD system and why?
The magnitude of the loop current must be considered because it could be high enough to blow fuses or overload URD equipment.
Where is the Communication Protocol to be followed by the PIC and field worker found?
SPR and SOO 1T-13
What category of PSSP must a worker be authorized to in order to receive an SPG?
CAT 5
What is a Designated Isolation Point? Where would a DIP be recorded?
A designated isolation point is used when equipotential grounding is not practicable (station feeder work). Worker woll identify to the PIC if a DIP is required. It is recorded on both FVO and field SPG forms.
What fundamental questions must be answered by the field worker when returning anSPG to the PIC?
Equipment ready for service
Worker Protection grounds applied
Workers clear, warned to stay clear
What System Operating Order defines the life cycle of an SPG card?
1T-07J
What are the PIC’s responsibilities following the return of an SPG declared “Not Ready for Service”?
Not ready for service box ticked and a note as to why
When new SPG is issued, worker must be informed that equipment is not ready for service
What are the PIC’s responsibilities following the return of an SPG with “Worker Protection Grounds Applied”?
Place field ground device symbol with the isolated zone and tag with a grounded tag (in Areva)
Place grounded tag on paper mimic display
What are the PIC’s responsibilities following the return of an SPG with phasing requirements?
Not available tag on electronic mimic display describing the phasing requirements.
What is a Guarantee of Isolation and how is a GOI recorded?
A means of effecting guaranteed isolation between different operating authorities. It is recorded in a SPG.
What is a Transfer of Operating Authority and how would a TOA be recorded between a Load Desk and adjacent Grid Desk at FVO?
A GOI is used to move the operating boundary between two PICS. It is logged in paper logs and TOA tag on device.
What category of PSSP must a worker be authorized to in order to receive a Live Line Permit?
CAT 5
What category of PSSP must a worker be authorized to in order to receive an Assurance of No Reclose Permit?
CAT 4
What is a Guarantee of No Reclose?
A stated and fully logged guarantee between two PICS of different operating authority that a specified conductor or equipment shall not be reclosed manually or automatically until the PIC who has received the guarantee authorized reclosing.
Whattool is used by the Load Operator to log the issuing and returning of Live LinePermits, Assurance of No Reclose Permits, and Guarantee of No Recloses?
CROW
What is the purpose of a CNE?
The CNE authorizes the Operating Authority to proceed with the initial system energization tests of electric system plant additions, modifications and replacements.
What part of the power system requires a CNE for the commissioning of equipment?
Substation Equipment
Following the completion of a CNE, what must be done if an updated EMS one-line displayis not ready for upload to reflect the changes to the system?
If the Electronic PSSP Mimic Display has not been updated, the PIC will set this condition by clicking on the “PSSP Mimic Display” text to display a drop down menu and poke the “Check Paper One-Line” red button. This will enable dynamic yellow text to flash and display “CHECK ONE-LINE”. This will be logged in CROW as an EMS/SCADA condition for the station with “XXX Check One-Line” in the event description where XXX is the station abbreviation. In the comments field, the Operator will describe the nature of the discrepancy between the Electronic PSSP Mimic Display and the temporary marked-up Paper One-Line.
What is a Plant Alteration?
The addition or removal of high voltage (less than 60kv) plant on the distribution system.
What part of the power system requires a PA for the addition and removal of plant?
60kv or less
What is the purpose of the PA process and what operating order is the process defined in?
To ensure all parties responsible for the operation of the electrical system maintain accurate and up to date operating drawings and mimics.
What is PAT?
Plant Alteration Tracking
Whatis the role of the PA Coordinator?
Manage the PAT tool
When working on a PA to install a new underground loop connection, at what point isa Safety Protection Guarantee required? (1D-01)
A SPG is required prior to termination of the cable at either end that will serve to create a loop on the system.
What are the Load Operator’s responsibilities following the completion of a PA?
Sign off
Date
Note name of electrical worker
Decide if new drawings are needed
Give to PA coordinator
Ensure all drawings and POCC are updated
What is a PACTOR?
Protection, Control and Telecom Operation Report
When commissioning protection, control, and telecommunications equipment; when is aPACTOR not required? (1T-36)
When protection, control and telecommunications equipment is commissioned concurrent to power system equipment then procedure listed in SOO 1T-35 should be followed and CNE is used rather than PACTOR form
Briefly describe the process for commissioning a brand new field recloser with supervisory control
A PA completion is required
Ensure that protection, control and telecommunications systems have been tested
Prior to allowing the device to be put in service, the control centre must add the device to the CROW database and the official mimic display
What is a Declaration of Compatibility?
A declaration of Compatibility form is used to commission distribution IPP’s. The IPP has the responsibility
What is differential protection?
Protection that will operate when it has determined that the difference between the current going into the transformer and coming out of the transformer has exceeded a pre-determined amount.
What is the advantage of using differential protection over simple over-current protection to protect transformers?
What is the limitation of using over-current relays to employ differential protection?
How do percentage differential relays increase the sensitivity of differential protection?
How can magnetizing inrush current pose a problem to differential protection?
How are a gas relay’s alarm and trip outputs triggered?
An alarm is initiated by detecting an accumulation of gas which may indicate a developing fault. Gas displaces the oil in the relay chamber, a float follows the oil and at a certain point initiates the alarm. A trip is initiated by an internal fault. Arcing caused by a fault will vapourize the oil resulting in a rapid buildup of gas pressure. A pressure wave moves a flexible bellows in the gas relay to operate a micro switch which initiates a trip.
What two conditions in combination will trigger “bullet-hole” protection?
Low oil alarm
Gas accumulation alarm
How does a winding temperature device measure temperature? What is it used for?
Measures temperature based on top oil temperature and the current in the transformer winding.
Protects against overload.
How are faults cleared on substation transformers without high-side circuit breakers?
Transfer trip
Just transfer trip? What about a SOG?
What is transformer auto isolation?
Following a transformer circuit breaker tripping to clear a fault, the disconnect switches are opened to isolate the transformer. The disconnects cannot be closed until lockout is reset.
What type of relay is generally used in bus protection?
Over current relay
How must the phase and neutral relays of bus protection be set in terms of coordination?
Phase relay – Set above max load current and coordinate with feeder phase over current relaysNeutral relays – Set above max neutral current and must coordinate with feeder neutral relays
What is the purpose of torque control and how does it function?
To ensure that bus protection does not operate on load current.
What is the risk in using the under-voltage method of torque control?
Loss of voltage to the under-voltage relay may cause bus protection operation.
Why would a distance relay be used to provide torque control?
A distance relay would be used when there may be insufficient voltage to operate an under-voltage relay.
What is the risk in using the distance method of torque control?
The risk in using the distance method is that if there is a loss of voltage to the distance relay will prevent bus protection operation for a bus phase fault.
Describe typical substation feeder relaying.
A typical substation feeder relay protections usually consist of 4 over-current relays. One for each phase and one for the neutral. Each relay usually consists of a timed element and an instantaneous element which would operate faster than the timed element for a high current fault.
How is a feeder fault cleared if the feeder circuit breaker fails to operate?
If the feeder breaker fails to open, the corresponding bus will trip.
How does a fused cut-out function?
If a transformer fails or the primary short circuits, the fuse link melts and the hinged portion will open.
What is an expulsion fuse?
Cut out fuses are call expulsion fuses because the heat generated by the melting creates gases that expel arc products from the fuse tube.
How does the fault protection provided by vista switchgear differ from that of aswitching kiosk?
Switching kiosks have fuses and Vistas have way switches.
How are the majority of dead-front transformers protected?
Expulsion fuses and back up current limiting fuses.
Can a bay-o-net fuse be used to break load in an LPT?
No
How are shunt capacitor banks primarily protected? What benefits does this provide?
Shunt capacitor banks are primarily protected by individual capacitor fuses.
What means of protection can be provided to isolate a shunt capacitor bank from thesystem in the event of a major fault?
Phase fuses or phase and ground over-current relays may be used between the system and the capacitor bank for major bank faults.
Why is neutral-shift over-voltage protection applied to shunt capacitor banks?
Neutral-shift over-voltage protection is applied incase there is a failure in one of the phases that would cause the neutral to swing on to the line potential causing a line to line voltage on the remaining two phases.
What type of feeder outage will a Load Operator be most concerned with?
Outages on level 4 portions of the feeder
What are the most typical causes of feederfaults?
· Trees
· MVA’s
· Animal contact
· Fire
· Ice
· Snow
· Failed equipment
What should a Load Operator suspect as the possible cause of a sustained feederfault when there has been no report or evidence as to the cause of the fault?
Failure of the feeder cable
What are some typical causes of substation equipment outages?
· Internal faults within a transformer, voltage regulator, reactor, etc
· Capacitor bank may trip offline due to can failures
· Circuit breakers and disconnects mail fail during operation
· vandalism
What has BC Hydro done within their substations to help prevent animals and birdsfrom causing equipment outages?
BC Hydro has installed animal and bird guarding to protect buses and equipment from being in contact.
Where is BC Hydro’s feeder reclosing policy documented?
1D-51
How long does a Load Operator have to attempt a manual reclose on a feeder circuitbreaker following a trip?
60 Seconds
How can a Load Operator determine if reclosing is permitted on a given feedercircuit?
Circuit breakers that are not permitted to be reclosed per 1D-51 appendix have an “X” inside the circuit breaker symbol in AREVA.
Where is BC Hydro’s distribution substation bus reclosing policy documented?
1T-29B
How can a Load Operator determine if bus reclosing is permitted at a givensubstation?
Substations that allow bus reclosing will have the text “Feeder Bus Reclosing in Effect” under the nameplate.
What is cold-load pickup?
Cold load pickup is the loading imposed on the system after prolonged service interruption which diversity among loads such as heaters, ranges and AC has been lost.
When is a feeder outage considered to be momentary and when is a feeder outageconsidered to be sustained? What are the Load Operator’s responsibilities interms of reporting?
Momentary - less than 60 seconds
Sustained – longer than 60 seconds
Report to HRC (and SCM or DSM when a major loss occurs)
How are Power Line Technicians dispatched?
HRC
How are Station Electricians and CPC Techs dispatched?
FVO - (1T-82)
General and role-specific logging procedures can be found in what operating order?
SOO 1T-07
What must a Load Operator first do upon assuming PIC duties?
Sign the log
When is a Switching Order required?
3 or more switching steps
The Switching Order procedure is defined in what operating order?
1T-06
Where are the definitions, rules, and procedures pertaining to Safety ProtectionGuarantees found?
SPR section 600
In addition to recording the issue of a Safety Protection Guarantee with an SPG card, what additional logging must take place?
The paper desk log will record the SPG number, Designation of lines or equipment to which the SPG applies and the time/date.
What is the purpose of POCC?
POCC mimics the level 4 trunk of the distribution system.
What operating order describes the guidelines for using and updating POCC?
1D-52
What operating order describes specifically how POCC is to be used as a mimic display?
1D-06
How are reclosers and SCADA switches displayed in POCC and why?
They are represented as a blue device to indicate that the device status must be verified in AREVA.
What does the “L” symbol displayed in the POCC Schematic Window represent?
The “L” symbol represents a level 4 loop.
What is a composite schematic?
A composite schematic displays multiple feeders on the same schematic so that the user can easily trace between circuits when switching involved more than one feeder.
Why is the POCC Geographic Window not used for operating in real time?
The POCC geographic window is not used because it is not kept up to date in real time when changes are made.
How can updates be made to POCC schematics in real time? What is the preferred method of updating a POCC schematic?
POCC schematics can be updated in real time electronically with the POCC schematic editing and redline tools or the user can print a paper copy of the POCC schematic, mark up the drawing by hand, and set the electronic document out of date. The preferred way is to update it electronically.
Generally speaking, what is the purpose of the CROW application?
Communication between field staff and Grid Ops staff
What line of operating orders are the CROW guidelines described in?
1T-54
What are the four different browsers within CROW?
· Outage requests
· Events
· Permit requests
· Station / field reclosing browser
What is a CROW Outage Request?
A formal process by which planned work is evaluated and approved by outage scheduling.
What must be done in CROW when an approved Outage Request is taken?
Implemented
When should an implemented Outage Request in CROW be completed?
When the distribution customer is returned to service or the distribution or station equipment becomes available to the system.
