What is the main purpose of a substation in a power system?
A To generate electricity
B To step up or step down voltage levels
C To store electrical energy
D To reduce electrical losses
Substations facilitate power transmission by stepping up voltage for long-distance transmission and stepping it down for local distribution, ensuring efficient energy delivery.
What is the primary function of a circuit breaker?
A To isolate a part of the system during maintenance
B To interrupt fault currents
C To control voltage levels
D To measure power flow
Circuit breakers automatically interrupt electrical flow in the event of faults, protecting equipment and maintaining system stability.
Which device in a substation is used to monitor voltage?
A Current transformer
B Potential transformer
C Circuit breaker
D Relay
Potential transformers (PTs) reduce high voltages to measurable levels for monitoring, metering, and protective relays.
What is the purpose of a grounding system in a substation?
A To prevent overcurrent
B To provide a safe path for fault currents to the ground
C To regulate frequency
D To step down voltage levels
Grounding systems ensure safety by directing fault currents into the earth, reducing equipment damage and protecting personnel.
What is the role of a power transformer in a substation?
A To change frequency
B To step up or step down voltage levels
C To regulate current flow
D To store electrical energy
Power transformers are critical in adjusting voltage levels for efficient transmission and distribution of electrical energy.
Which substation component is used to protect equipment from lightning-induced surges?
A Circuit breaker
B Lightning arrester
C Isolator
D Relay
Lightning arresters protect substation equipment by diverting high-voltage surges caused by lightning to the ground.
What is the purpose of a relay in a substation?
A To step up voltage
B To detect and isolate faults
C To increase current flow
D To monitor power factor
Relays sense abnormal conditions such as overcurrent or short circuits and signal circuit breakers to disconnect faulty sections.
What is the typical voltage range for a distribution substation?
A 33 kV to 220 kV
B 11 kV to 33 kV
C 400 kV and above
D Below 11 kV
Distribution substations typically operate in the range of 11 kV to 33 kV to step down power for local use.
Which substation layout is commonly used for compact urban areas?
A Outdoor layout
B Indoor layout
C Hybrid layout
D Modular layout
Indoor substation layouts are compact and enclosed, making them ideal for space-constrained urban areas.
What is the purpose of a busbar in a substation?
A To store electrical energy
B To collect and distribute power to outgoing feeders
C To control fault current
D To measure current flow
Busbars are metallic strips or bars that act as connection points, distributing power to multiple circuits within the substation.
What does the term “switchgear” refer to in substations?
A Voltage regulating devices
B Protective devices like circuit breakers and isolators
C Transformers
D Metering equipment
Switchgear encompasses all devices that protect, control, and isolate circuits, ensuring safe and reliable operation.
Which test measures the insulation strength of substation equipment?
A Load test
B Dielectric test
C Relay test
D Power factor test
Dielectric tests evaluate the insulation strength of substation equipment to withstand high voltages without breakdown.
What is the purpose of shunt capacitors in substations?
A To step up voltage levels
B To provide reactive power and improve power factor
C To protect equipment from surges
D To disconnect faulty sections
Shunt capacitors supply reactive power to maintain voltage stability and improve the system’s power factor.
What is the main advantage of gas-insulated substations (GIS)?
A Lower cost
B Compact size and suitability for harsh environments
C Easier maintenance
D Higher voltage regulation
GIS is compact and designed for use in areas with limited space or harsh environmental conditions.
What is the role of a load break switch?
A To interrupt fault currents
B To disconnect loads under normal operating conditions
C To measure system frequency
D To regulate reactive power
Load break switches are manually or automatically operated devices that disconnect circuits during normal load conditions.
What does “fault current” refer to in substations?
A Normal operating current
B Excess current caused by a fault like a short circuit
C Current used for grounding
D Backup current during maintenance
Fault current is an abnormally high current that flows during fault conditions, requiring protective devices to handle it.
What is the purpose of a control panel in a substation?
A To step down voltage levels
B To monitor and control equipment operation
C To regulate frequency
D To provide grounding
Control panels house equipment used for monitoring, protection, and controlling the operation of substation systems.
Which device is used for voltage control in substations?
A Tap changer
B Relay
C Isolator
D Lightning arrester
Tap changers adjust the transformer winding connections to regulate voltage levels during varying load conditions.
What is the purpose of a protective relay?
A To interrupt the main supply
B To detect abnormal conditions and signal circuit breakers
C To step up voltage levels
D To store electrical energy
Protective relays sense issues like overcurrent or short circuits and initiate circuit breaker operations to protect the system.
What is the importance of insulation coordination in substations?
A To increase power factor
B To match insulation levels with expected voltage stresses
C To reduce transmission losses
D To improve grounding systems
Insulation coordination ensures equipment can withstand voltage surges without failure, enhancing reliability and safety.