Electrical Distribution Quiz

Why is alternating current (AC) used instead of direct current (DC) in electrical supply systems?

• AC can be easily transformed from one voltage to another

• AC produces less arcing and sparking on contacts

• Transmission losses are lower with low current

• All of the above

What is the purpose of using transformers in the transmission and distribution system?

• To step-up and step-down voltages

• To reduce switchgear and fuse gear ratings

• To balance the load on the supply system

• To reduce cable sizes

Which cooling method is generally used for small transformers up to 3MVA?

• Air cooled

• Oil cooled

• Gas cooled (Sf6)

• None of the above

What is the purpose of balancing the load across the phases in a three-phase supply?

• To prevent any one phase from being overloaded

• To reduce transmission losses

• To increase the voltage drop in the cables

• To improve power factor

What voltage is typically used for local distribution in England and Wales?

• 11kV

• 33kV

• 132kV

• 400kV

Which cooling method is generally used for transformers up to about 30MVA?

• Air cooled

• Oil cooled

• Gas cooled (Sf6)

• None of the above

What is the purpose of using a three-phase and neutral supply for industrial installations?

• To provide a choice of two voltages

• To reduce switchgear and fuse gear ratings

• To balance the load on the supply system

• To reduce cable sizes

What is the maximum current rating (In) fitted in the Distribution Network Operator (DNO) service cut-out for a domestic premise?

• 50 amperes

• 100 amperes

• 200 amperes

• 400 amperes

What are the separate electrical items commonly found in a sub-station?

• Transformers, isolators, fuses/circuit breakers, switchgear

• Generators, transformers, cables, meters

• Motors, capacitors, resistors, relays

• Batteries, inverters, solar panels, wind turbines