WorksheetsKnowledge test V3
Total questions: 40
Worksheet time: 3600secs
Which of the following circuits provides the ability to switch on the network and restore supplies more efficiently in the event of a fault
A parallel circuit without an open point
A ring circuit with an open point
A radial circuit with an open point
A radial circuit without an open point
The Electricity Safety, Quality and Continuity Regulations 2002 place duties on persons to report certain instances. Which ONE of the following is NOT reportable under ESQCR?
Major interruption to the electricity supply
Domestic fatalities attributed to electrical equipment
Serious injuries, fires and explosions
Volume of CO2 emitted by the organisation's vehicles and equipment
The formula for calculating the resistance of a circuit can be expressed as:
R = V²/I
R = P/I²
R = V/R
R = P/I
Which of the following is used to describe the typical purpose of an automatic voltage control relay on the operation of transformer's?
Monitor the transformer's tap changer and send an automated signal to network control
Control the transformer's input and output via a tap changer to keep it within it's statutory limits
Monitor the transformer's temperature and control its voltage output to prevent damage to the transformer
Monitor the transformer's output voltage and control its tap changer to keep the voltage within its statutory limits
Which of the following describes the effect of harmonics on power transformer's?
The voltage regulation improves the system losses and reduces the over-stressing of insulation materials by reducing the effect of heat
The voltage distortion increases transformer efficiency by raising the voltage and lowering the current produced by the windings
The voltage distortion decreases transformer efficiency by raising the voltage and lowering the current produced by the windings
The voltage distortion increases the losses causing the over-stressing of insulation materials through the generation of additional heat
Which of the following is NOT in the Electricity at Work Regulations?
All systems shall at all times be of such construction as to prevent, so far as reasonably practicable, danger
Based on cost and time, certain activities shall be carried out in such a manner as not to give rise, so far as reasonably practicable, to danger
As may be necessary to prevent danger, all systems shall be maintained so as to prevent, so far as reasonably practicable, such danger
Any equipment provided under these Regulations for the purpose of protecting persons at work on or near electrical equipment shall be suitable for the use for which it is provided, be maintained in a condition suitable for that use, and properly used.
A delta - star connected transformer has its:
Primary winding star-connected and its secondary winding delta-connected
Primary and secondary winding inter-connected
Primary and secondary winding both in delta-star
Secondary winding start-connected and its primary winding delta-connected
Which of the following identifies the typical voltage tolerances for UK low voltage (up to 1000v) and high voltage (up to 132kV) power networks?
LV +6% and -10%, High Voltage ± 6% of nominal voltage
LV +10% and -6%, High Voltage ± 6% of nominal voltage
LV ± 5% High Voltage - 10% of nominal voltage
LV ± 6 High Voltage ± 10% of nominal voltage
Ofgem's RIIO (Revenue = Incentives + Innovation + Outputs) price controls are designed to encourage?
Price competition between transmission and distribution companies which improve costs and reduce the cost of supply
Price competition between transmission and distribution companies which reduce the cost of supply regardless of the cost
Network companies to deliver a sustainable energy sector in a way that brings consumers value for money
Network companies to reduce the amount of system faults and penalise Company's which fail to meet the standards
Electricity is typically generated in large commercial power stations at:
400V
230V
25kV
132kV
A power network circuit with a low power factor will generally use:
Lower currents to transfer a given quantity of real power than a circuit with a high power factor
Higher currents to transfer a given quantity of real power than a circuit with a high power factor
Higher voltage to transfer a given quantity of real power than a circuit with a high power factor
Lower resistance to transfer a given quantity of real power than a circuit with a high power factor
Voltage transformer's (VT) can be used for circuit control, safety protection and measurement, but which of the following describes the principle of its operation
Step up the voltage of the system to a value which is acceptable to the higher rating of meters and relays
Convert the alternating waveform of the system to a direct waveform to supply meters and relays
Step down the voltage of the system to a value which is acceptable to the lower rating of meters and relays
Accept the voltage of the system and connect it directly to the higher rater meters and relays
The electricity supply to a domestic consumer is usually protected at the incoming service position by a:
Meter
Double pole switch
100A MCB
100A HBC fuse
The maximum amount of current that will flow in the case of a short circuit at a point in the system is known as:
Fault level
Current level
Voltage level
Maximum Resistance level
Identify the correct order of the 5-step risk assessment:
1. Identify the hazards
2. Evaluate the risks effect and likelihood
3. Assess the risk and take action
4. Record
5. Review and monitor
1. Evaluate the risks effect and likelihood
2. Identify the hazards
3. Assess the risk and take action
4. Record
5. Review and monitor
1. Identify the hazards
2. Assess the risk and take action
3. Evaluate the risks effect and likelihood
4. Review and monitor
5. Record
1. Identify the hazards
2. Evaluate the risks effect and likelihood
3. Review and monitor
4. Assess the risk and take action
5. Record
Complete the sentence:
A typical capabilities of a high voltage SF6 circuit breaker can make and break load ..........
but only make fault current
but not make or break fault current
and make and break fault current
but only break fault current
What is meant by the term achieving 'Safety from the System'?
That all equipment shall be made dead prior to any work activities permitted on the electrical network
The condition which safeguards equipment from the dangers of work being conducted on the electrical network
The condition which safeguards persons working on or near to equipment from the dangers which are inherent in a system
The condition which safeguards persons, tools, equipment and plant when working on or near the electrical system
three phase transformer' may only be connected in parallel when?
They are identical in all respects
They have exactly the same losses
The permission of the transformer manufacturer is obtained
They have the same secondary voltages
In a balanced three-phase system with star-connected load and 415V line voltage, the phase voltage is:
415V
240V
0V
719V
Which of the following statements is NOT one of Ofgem's primary goals?
Use price controls to limit what transmission and distribution charge
Prescribe robust safety and working methods for the transmission and distribution of power
Set targets for reliability, customer service and environmental performance
Encourage companies to innovate to cut costs for consumers and operate efficiently
A relay that operates by the principle that the higher the current value the lesser the time it will take for the relay to operate is known as following which protocol?
Immediate Delay Measured Sequence (IDMS) protocol
Inverse Decision Time Measure (IDTM) protocol
Individual Delayed Time Sequence (IDTS) protocol
Inverse Definite Minimum Time (IDMT) protocol
The Electricity at Work Regulations 1989 state that "Generally, you should do everything reasonably practicable to protect people from harm". What does reasonably practicable mean in this instance?
Reasonably Practicable means gauging the level of harm which may be inflicted against set costs needed to control the level of risk
Reasonably Practicable means costing the level of risk against the time and inconvenience of providing protection in all conditions
Reasonably Practicable means implementing all necessary control measures at all times regardless of the level of risk, time and inconvenience
Reasonably Practicable means balancing the level of risk against the measures needed to control the real risk in terms of money, time or trouble
Which one of the following identifies the primary purpose of a Risk Management Strategy?
Cost efficient approach to identifying, assessing and managing the company's financial risk
Clear and coherent legally binding methods of reducing a company's exposure to risk
Structured and coherent approach to identifying, assessing and managing risk
Auditable process which protects a company from liability in the event of an incident
What effect will increasing the number of secondary turns on a transformer winding connected to an AC supply have on the voltage?
Decrease the output voltage
Decrease the input voltage
Increase the input voltage
Increase the output voltage
The formula for calculating the voltage in a circuit can be expressed as:
V = P²/R
V = P/R
V = P/I
V = R x I²
Power factor correction is applied to an AC circuit in order to create the conditions where the:
Current leads the voltage
Voltage leads the current
Voltage and current are out of phase
Voltage and current are in phase
In a balanced three-phase system with delta-connected load and 10A line current, the phase current is:
10A
17.3A
5.77A
30A
Which of the following identifies the typical maximum permitted earth fault loop impedance values for UK distribution low voltage networks?
PME - (TNCS) 2.0Ω Cable sheath/Separate (TN-S) - 1.0Ω
PME - (TNCS) 2.0Ω Cable sheath/Separate (TN-S) - 10Ω
PME - (TNCS) 0.8Ω Cable sheath/Separate (TN-S) - 0.35Ω
PME - (TNCS) 0.35Ω Cable sheath/Separate (TN-S) - 0.8Ω
Power factor correction in an AC power circuit can be achieved by:
Removing capacitors or inductors that act to cancel the inductive or capacitive effects
Adding capacitors or inductors that act to raise the inductive or capacitive effects
Adding capacitors or inductors that act to cancel the inductive or capacitive effects
Raising circuit voltage to cancel the inductive or capacitive effects
Which one of the diagrams identifies the correct connection of an ammeter, a voltmeter and a wattmeter in a single phase circuit?
a
b
c
d
Which of the harmonics typically causes neutral current to increase most significantly?
The fifth harmonic
The third harmonic
The seventh harmonic
All of the above contribute equally
In a balanced three phase system the neutral current is equal to:
Line current
Phase current
3 x phase current
Zero
A no-earth provided supply is also called a:
TT system
TN-S system
TN-C-S system
Standby system
Which of the following describes the typical method of operation for a Buchholz relay within a power transformer?
A Buchholz relay detects voltage changes within a transformer's windings to prevent internal faults
A Buchholz relay detects changes in a transformer's oil flow or gas pressure to detect internal faults
A Buchholz relay monitors changes in oil temperature to control the operation of a circuit breaker
A Buchholz relay monitors the current flow in a transformer's windings to control output voltage
Which piece of network equipment does the following describe - It reduces earth fault currents and limits the amount of fault current returning to the neutral point of a power transformer?
A switch fuse
A voltage transformer
A protective multiple earth
A neutral earthing resistor
Select the correct answer to complete the statement:
The term transient fault describes a fault which typically affects the network .......
intermittently for short periods of time
immediately and permanently
when the network is isolated and earthed
by being detected at different locations on the network
A permit-to-work system is a formal written system used to control certain types of work that are potentially hazardous.
A "permit-to-work" document specifies the:
Work to be done and the time to be taken to complete the work safely, based on a risk assessment
Work to be done and the precautions to be taken to complete the work, based on the time and cost of delivery
Work to be done and the precautions to be considered to complete the work effectively in the set timescale
Work to be done and the precautions to be taken to complete the work safely, based on a risk assessment
In relation to commercial projects, the Construction Design and Management (CDM) Regulations 2015, require that under certain circumstances construction work is notifiable in writing to the HSE.
Which one of the following statement's identifies those circumstances, where planned construction work will last longer than?
20 working days and involves more than 10 workers at any one time; or where the work exceeds 200 individual worker days
50 working days and involves more than 30 workers at any one time; or where the work exceeds 100 individual worker days
30 working days and involves more than 20 workers at any one time; or where the work exceeds 500 individual worker days
40 working days and involves more than 15 workers at any one time; or where the work exceeds 300 individual worker days
The Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR) places duties to report certain incidents that may involve the safety of those not employed by the duty holder.
Which of the following identifies two of these incidents?
Any single interruption of supply of 5 megawatts or more at the time of the interruption for a period of one hour or longer
Any single interruption to 5000 or more consumer's installations for a period of one hour or longer
Any single interruption of supply of 1 megawatt or more at the time of the interruption for a period of five hours or longer
Any single interruption to 1000 or more consumer's installations for a period of five hours or longer
Any multiple interruption of supply of 20 megawatts or more for more than two 5 minute periods
Any single interruption of supply to 10,000 or more consumer's installations for a period of two hours or longer
Any single interruption of supply of 20 megawatts or more at the time of the interruption for a period of one hour or longer
Any single interruption to 10,000 or more consumer's installations for a period of one hour or longer
The Construction Design and Management Regulations 2015 (CDM) places certain duties on "Commercial Clients" for whom a construction project is being carried out as part of their business. Which ONE of the following is NOT one of those duties?
Manage the project to ensure sufficient time and resources are allocated
Ensure relevant information is prepared and provided to other duty holders
Ensure the principal designer and principal contractor carry out their duties
Manage the time and working arrangements of all contractors on site
