Protective Relaying Quiz

What is the primary purpose of protective relaying in power systems?

• To increase system voltage

• To detect abnormal conditions and initiate corrective actions

• To reduce energy consumption

• To regulate frequency

• To connect distributed generators

A directional relay determines the direction of fault current relative to:

• Frequency

• A voltage reference

• Ground resistance

• System capacitance

• Load impedance

Which component reduces the system voltage to a level suitable for a directional relay?

• Current transformer (CT)

• Potential transformer (PT)

• Circuit breaker

• Overcurrent coil

• Differential relay

In feeder protection, directional relays are used to isolate:

• Overvoltages

• Reverse power flow

• Faults in specific directions

• Harmonic distortions

• Load imbalances

The 'directional coil' in a directional relay receives signals from:

• Potential transformer

• Current transformer

• Voltage regulator

• Capacitor bank

• Grounding resistor

Distance relays operate based on the measurement of:

• Frequency

• Impedance

• Power factor

• Harmonic distortion

• Voltage magnitude

How does a distance relay estimate fault location?

• By comparing phase angles

• By calculating the ratio of voltage and current (impedance)

• By monitoring temperature rise

• By detecting ground resistance

• By measuring power loss

Which application is NOT typical for distance relays?

• Protection of transmission lines

• Busbar protection

• Transformer overcurrent protection

• Long-distance line fault detection

• Generator synchronization

A distance relay trips when the measured impedance is:

• Equal to the relay setting

• Greater than the relay setting

• Less than the relay setting

• Unaffected by fault location

• Proportional to frequency

The restoring torque in a distance relay is produced by:

• Current transformer

• Potential transformer

• Overcurrent coil

• Directional coil

• Communication channel