Learning Outcome 4

What is the purpose of isolator in substation installations?

• To adjust the output voltage of a transformer

• To disconnect a circuit from the rest of the system

• To oppose the change in current or voltage in a circuit

What is the function of tap changers in substation installations?

• To adjust the output voltage of a transformer

• To disconnect a circuit from the rest of the system

• To interrupt the flow of current in a circuit

• To oppose the change in current or voltage in a circuit

What is the primary reason for the earthing of the neutral point in high voltage and low voltage systems?

• To provide a reference point for the system voltage

• To limit the fault current that flows through the earth

• To create an intentional earth fault on a feeder or a busbar

• To oppose the change in current or voltage in a circuit

Why is bonding and earthing of metalwork important in substation installations?

• To adjust the output voltage of a transformer

• To disconnect a circuit from the rest of the system

• To ensure all metal parts are at the same potential as the earth

• To oppose the change in current or voltage in a circuit

What is the reason for measuring the earth resistance value of earth electrodes in substation installations?

• To verify the adequacy of the earth electrodes

• To adjust the output voltage of a transformer

• To disconnect a circuit from the rest of the system

• To oppose the change in current or voltage in a circuit

What is the meaning of earth resistance in substation installations?

• The resistance of a unit volume of soil to the flow of current

• The resistance offered by an earth electrode or an earthing system

• The impedance of the path followed by the fault current in case of an earth fault

• The resistance of the metal parts in contact with the earth

What is the function of bus section switches in substation installations?

• To divide the busbar into sections

• To connect two busbars together

• To adjust the output voltage of a transformer

• To oppose the change in current or voltage in a circuit

What is the purpose of interlock systems and mechanisms in substation installations?

• To divide the busbar into sections

• To connect two busbars together

• To prevent unsafe or incorrect operations

• To oppose the change in current or voltage in a circuit

What is the reason for using bus coupler switches in substation installations?

• To divide the busbar into sections

• To connect two busbars together

• To adjust the output voltage of a transformer

• To oppose the change in current or voltage in a circuit