WorksheetsSystem Operation — Study Guide Key (Chapter 1)
Total questions: 49
Worksheet time: 25mins
For each system there is typically a central point from which operation of the system is conducted. This is called the ________.
Operations center
Control panel
Service desk
Command post
The title that is widely recognized as a highly skilled and knowledgeable individual who monitors and directs the operation of the power system is ________.
System operator
Line technician
Power dispatcher
Grid analyst
The jurisdiction of an operating center refers to:
The geographic area and scope of authority managed by the operating center.
The number of employees working at the operating center.
The financial budget allocated to the operating center.
The type of equipment used at the operating center.
The system operator uses the wall maps to:
monitor and manage the system's operations
decorate the control room
track employee attendance
display company advertisements
What does NERC stand for, and how might this organization affect a system operator?
North American Reliability Council Certification Program establishes standards of competency for system operators who operate the interconnected transmission grids.
National Energy Resource Commission oversees the distribution of natural gas in North America.
Nuclear Emergency Response Committee manages nuclear plant safety protocols.
National Environmental Regulation Council enforces environmental laws for power plants.
Define the term: Clearance.
A formally recognized condition of a line, line section, or equipment that has been de-energized from all potential sources of energy by opening devices in the path or the potential flow of power.
A process of increasing the voltage in a transmission line to improve efficiency.
A method of measuring the resistance of electrical equipment.
A type of maintenance performed on energized equipment.
Define the term: Clearance point.
Any device, connector, or open that is used to isolate the line or piece of equipment from a potential source of energy.
A point where two electrical circuits meet and transfer power.
A location where safety equipment is stored.
A device used to increase the voltage in a circuit.
Define the term: Energy sources.
Specific sources of energy that potentially could energize a line, line section, or piece of equipment that needs to be cleared and worked on.
A type of renewable energy that is always available.
A device used to store electrical energy for later use.
A process of converting mechanical energy into electrical energy.
What are the three main objectives that apply to clearing lines and equipment?
To assure the safety of those employees who may be working to clear the line and those employees who will be working on the line or piece of equipment, to minimize the impact to reliability and capacity of the system that will occur as a result of the clearing of the line or piece of equipment, to minimize the number of customers who will be out of service.
not this one
not this one either
im bored
What is the difference between a clearance point and a visual clearance point?
A clearance point is any device, connector, or open that is used to isolate the line or piece of equipment from a potential source of energy. A visual clearance point provides a clear visual air gap between the source and load terminals of a device.
A clearance point is only used for grounding, while a visual clearance point is used for isolating equipment.
A clearance point is a type of warning sign, while a visual clearance point is a type of lockout device.
A clearance point and a visual clearance point are the same and can be used interchangeably.
What type of information would typically be found on a hold tag?
Do not operate, order number, switch/device number, circuit number, date and time of tag placement, name of person attaching tag, phone number, and service operator information.
Only the name of the supervisor and the company logo.
A list of all employees working in the area.
Instructions for cleaning the equipment.
Why would an operating center need three days to process a line clearance?
To check loading, protection settings, and other information.
Because it is a standard waiting period for all requests.
To allow for equipment cooling regardless of situation.
To wait for approval from unrelated departments.
To switch around an outage using a map from your system, what would you do?
Identify the affected area, isolate the outage, reroute power, and restore service.
Ignore the outage and wait for it to resolve itself.
Increase the load on the affected area to test the system.
Shut down the entire system to prevent further issues.
Define the term 'Cold-load inrush'.
The amount of load that will be connected when the system or portions of the system are energized after being out of service for an extended period of time. It can be as high as 10 times the normal system load.
The process of reducing system voltage to prevent equipment damage during peak demand.
A method of cooling transformers during high load conditions.
The sudden drop in voltage when a generator is disconnected from the grid.
Define the term 'Looping'.
An operation where two branches of the same circuit are connected together.
A process of increasing the resistance in a circuit.
A method of reducing voltage in a circuit.
A technique for measuring current flow.
Define the term 'Non-reclose condition'.
The temporary disabling of a reclosing feature of a circuit breaker or recloser. Also commonly referred to as 'one-shot,' 'hot line hold,' 'hot line clearance,' or 'non test.'
A condition where a circuit breaker is permanently closed.
A situation where a circuit remains energized after a fault is cleared automatically.
The process of manually resetting a circuit breaker after every trip.
Define the term 'Null point'.
When two circuits are tied together in parallel, the flow of power is from the source of each circuit out to a 'null point,' where no current is flowing.
A point in a circuit where the voltage is always maximum.
A location in a circuit where all the current is diverted to ground.
A point in a circuit where resistance is zero and current is infinite.
Define the term 'Reclosing relay'.
A relay that controls how a breaker reacts during a fault. This relay can be preset to allow the breaker to open and reclose for a set number of times. It can be disabled to prevent any reclosing, if desired.
A relay that measures the current in a circuit and trips the breaker if it exceeds a set value.
A relay that is used only for voltage regulation in transformers.
A relay that is used to synchronize two generators before connecting them to the grid.
List three reasons for paralleling distribution circuits.
1. Transfer load from one circuit to another to distribute load as needed. 2. Clear a piece of equipment in a substation. 3. Transfer load from one circuit to another in conjunction with clearing a section of line.
1. Increase the voltage beyond safe limits. 2. Reduce the number of substations required. 3. Eliminate the need for circuit breakers.
1. To increase the resistance of the circuit. 2. To decrease the reliability of the system. 3. To overload the transformers intentionally.
1. To make the system more complex. 2. To reduce the efficiency of power delivery. 3. To increase the risk of faults.
When paralleling circuits, should the ground relays be enabled or disabled? Also explain the reason for your answer.
Ground relays should be disabled because an unbalanced condition can cause excessive neutral current, leading to unnecessary tripping of the recloser or breaker.
Ground relays should be enabled to ensure maximum sensitivity to ground faults during paralleling.
Ground relays should be disabled to allow for higher load sharing between circuits.
Ground relays should be enabled to prevent any possibility of neutral current flow.
List four requirements that are needed to parallel distribution circuits. (For more information, refer to section 3.4 of the manual)
1. Line-to-ground and phase-to-phase voltages must be the same. 2. The angular displacement of the transformer banks must be identical. 3. The phases must always match each other across the paralleling point. 4. The frequency of each system must be the same.
1. The transformer banks must have different angular displacement. 2. The frequency of each system can be different. 3. The phases do not need to match across the paralleling point. 4. Line-to-ground voltages can be different.
1. Only the phase-to-phase voltages must be the same. 2. The angular displacement of the transformer banks can vary. 3. The frequency of each system can be different. 4. The phases must not match across the paralleling point.
1. The transformer banks must be of different sizes. 2. The frequency of each system must be different. 3. The phases must be mismatched across the paralleling point. 4. Line-to-ground voltages must be different.
List the steps for clearing a line regulator. (For more information, refer to section 3.8 of the manual)
1. Place on manual position. 2. Adjust to neutral position. 3. Verify on neutral position. 4. Set control to off. 5. Close bypassing regulator. 6. Open install hold tag. 7. Open install hold tag.
1. Set control to off. 2. Open bypassing regulator. 3. Place on automatic position. 4. Adjust to maximum position. 5. Close install hold tag. 6. Verify on maximum position. 7. Open install hold tag.
1. Place on automatic position. 2. Adjust to maximum position. 3. Verify on maximum position. 4. Set control to on. 5. Open bypassing regulator. 6. Close install hold tag. 7. Close install hold tag.
1. Set control to on. 2. Adjust to minimum position. 3. Verify on minimum position. 4. Place on manual position. 5. Open bypassing regulator. 6. Close install hold tag. 7. Open install hold tag.
Explain what is meant by distributed generation and list at least four operating concerns.
Distributed generation refers to generating units that supply power to customer loads and provide excess power to the utility’s distribution system. Four operating concerns are: 1) Additional source of energy during line clearing, 2) Contribution to fault current, 3) Need for prompt disconnection during faults, 4) Risk of islanding and substandard voltage/frequency.
Distributed generation refers to centralized power plants that only supply power to the transmission grid. Four operating concerns are: 1) Reduced energy efficiency, 2) Increased transmission losses, 3) Higher maintenance costs, 4) Limited integration with renewable sources.
Distributed generation refers to the use of batteries for backup power only. Four operating concerns are: 1) Battery degradation, 2) Limited storage capacity, 3) High replacement cost, 4) Slow recharge rates.
Distributed generation refers to power generation that only occurs during peak demand periods. Four operating concerns are: 1) Overloading of main grid, 2) Increased fuel consumption, 3) Higher emissions, 4) Reduced reliability.
Which of the following is the correct switching order to clear a capacitor bank?
Open the capacitor bank circuit breaker, then open the isolators, and finally discharge the capacitors.
Open the isolators first, then the circuit breaker, and finally discharge the capacitors.
Discharge the capacitors first, then open the circuit breaker, and finally open the isolators.
Open the circuit breaker, discharge the capacitors, and then open the isolators.
Which of the following is the correct switching order to clear a recloser?
Open the upstream breaker, open the recloser, tag and ground as required
Close the recloser, open the downstream breaker, tag and ground as required
Open the recloser, close the upstream breaker, tag and ground as required
Open the downstream breaker, close the recloser, tag and ground as required
Fill in the blank: A ________ houses the circuit breaker in a metal cubicle inside a metal clad building.
metal clad switchgear
distribution board
panel board
fuse box
You would be likely to refer to the single-line diagram in a substation when:
analyzing the electrical connections and layout
measuring the physical dimensions of equipment
ordering replacement parts for transformers
painting the substation walls
The equipment in substations that is routinely cleared for maintenance is:
Circuit breakers
Transformers
Lightning arresters
Current transformers
The purpose of the transfer or auxiliary bus in a substation is to:
Provide an alternative path for power flow during maintenance or fault conditions
Increase the voltage level in the substation
Reduce the number of transformers required
Act as the main source of power supply
Which of the following lists the steps commonly followed to test an existing transformer bank in a substation?
Visual inspection, insulation resistance test, turns ratio test, oil testing, load test
Only visual inspection and oil testing
Turns ratio test and insulation resistance test only
Load test and visual inspection only
Guidelines that should be followed when operating hook-type disconnects in substations include:
Ensuring the disconnect is de-energized before operation
Operating the disconnect without checking for load
Standing directly under the disconnect during operation
Ignoring personal protective equipment requirements
When testing a substation bus, the reclosing relay on the breaker being used to test the bus should be:
Enabled
Disabled
Set to manual mode
Left in automatic mode
Select the correct switching order to clear a regulator.
Bypass, open regulator, close inlet and outlet valves
Close outlet valve, open bypass, close inlet valve, open regulator
Open regulator, close bypass, open inlet and outlet valves
Close inlet valve, open regulator, close bypass, open outlet valve
Which of the following is the correct sequence of steps to clear a circuit breaker?
Open the isolator, open the circuit breaker, then open the earth switch.
Open the circuit breaker, open the isolator, then open the earth switch.
Open the earth switch, open the isolator, then open the circuit breaker.
Open the circuit breaker, open the earth switch, then open the isolator.
What is the term for this phenomenon?
Ferranti effect
Skin effect
Corona effect
Proximity effect
Loop switching – This type of switching involves the connecting and disconnecting of transmission lines supplied from different sources of power. What is the term for this process?
Loop switching
Load shedding
Phase shifting
Voltage regulation
What is the term for this instrument?
Oscillograph
Barometer
Ammeter
Hygrometer
What is the term for the phenomenon that can occur when an arc is being interrupted?
Re-strike
Arc quenching
Flashover
Dielectric recovery
What is the term for this process?
Single pole relaying
Double pole relaying
Overcurrent protection
Differential protection
What is the term for this flow?
VAR flow
Turbulent flow
Laminar flow
Steady flow
Where do the losses occur in a typical system?
VAR flow losses (For more information, refer to section 5.7 of the manual)
At the power source only
In the user interface module
Only during system shutdown
What is the typical temperature range for a power arc?
5,000 to 25,000 degrees Celsius (For more information, refer to section 5.2 of the manual)
500 to 2,000 degrees Celsius
25,000 to 50,000 degrees Celsius
100 to 500 degrees Celsius
When de-energizing a line with no load connected, the operator will typically experience what two conditions?
High voltage and lower amperage (For more information, refer to section 5.2 of the manual)
Low voltage and higher amperage
High voltage and higher amperage
Low voltage and lower amperage
Explain the purpose of a ground switch.
When personal protective grounds are applied, a large arc can be encountered. To mitigate this problem some companies install grounding switches at the terminal ends of certain lines. The ground switches are typically installed as part of a regular switch and interlocked in a manner that the ground switch cannot be closed if the regular switch is closed. (For more information, refer to section 5.2 of the manual)
A ground switch is used to increase the voltage on a transmission line for testing purposes.
Ground switches are installed to provide additional lighting during maintenance work.
The purpose of a ground switch is to disconnect the main power supply during normal operation.
Why is it important to take load readings during loop switching?
To ensure that switching devices are capable of interrupting the current. Load readings can also indicate abnormal conditions that may help to locate trouble. (For more information, refer to section 5.3 of the manual)
To reduce the voltage in the circuit during switching.
To increase the efficiency of the transformer.
To prevent the need for regular maintenance checks.
List five common indicators of potential voltage or VAR flow problems on the system.
Voltage oscillations at high loads, abnormally high or low voltage at key substations, higher than normal VAR flow, VAR flow in an abnormal direction, and load tap changers or voltage regulators on an extreme high or low tap position.
Frequent transformer failures, increased power factor, reduced line losses, and stable voltage profiles.
Consistently low system frequency, increased generator output, reduced transformer tap changes, and balanced phase voltages.
High system inertia, low transmission line loading, increased system frequency, and minimal VAR flow.
What does the term "restrike" mean?
The phenomena that can occur when an arc is being interrupted. As the switch contacts are being opened, and the arc is interrupted at the current zero, a high level of voltage tries to continue to force power across the gap. If the level of the voltage is greater than the strength of the dielectric between the contacts, the arc can be re-established (restrike).
A process of increasing the current in a circuit to prevent arc formation.
A method of cooling electrical contacts to avoid overheating.
A technique used to reduce the voltage across open contacts in a switch.
Clearing a transmission line when poles need replacing requires which of the following steps in the switching order?
Isolate and de-energize the line, apply grounding, and issue work permits.
Increase the voltage on the line before work begins.
Leave the line energized and replace poles directly.
Bypass the switching order and proceed with replacement.
Transferring the load from one transmission line to another requires writing out a switching order. Which of the following is the correct sequence for this process?
Open the circuit breaker of the loaded line, close the isolator, then close the circuit breaker of the alternate line.
Close the isolator of the loaded line, open the circuit breaker, then close the circuit breaker of the alternate line.
Open the isolator of the alternate line, close the circuit breaker of the loaded line, then open the circuit breaker of the alternate line.
Close the circuit breaker of the alternate line, open the circuit breaker of the loaded line, then open the isolator of the loaded line.
