Electrical Engineering Quiz 3

List three things that need to be checked regarding the materials, given on a material schedule, before they are obtained and installed.

• Color, size, and price

• Durability, availability, and cost

• Quality, compatibility with the project, and environmental impact

• Weight, texture, and fire resistance

Tags

NGSS.HS-ETS1-3

List three methods of generating electricity using renewable energy.

• Solar, Wind, and Hydroelectric

• Coal, Natural Gas, and Nuclear

• Biomass, Geothermal, and Tidal

• Oil, Peat, and Diesel

Tags

NGSS.HS-ESS3-2

NGSS.HS-ETS1-1

Explain one reason why AC is used in preference to DC for most electrical distribution in the UK.

• AC can be easily converted to different voltages using transformers

• DC is more efficient than AC

• AC is more expensive than DC

• DC is safer to transmit over long distances

List three types of AC motor controller.

• Soft start, Rotor resistance, Direct online

• Pulse-width modulation, Voltage controller, and Slip ring induction

• Direct torque control, Slip ring induction, and Synchronous motors

• Frequency converter, Pulse-width modulation, and Brushless DC

Tags

NGSS.HS-PS3-5

Determine the neutral current within a three-phase circuit where the current for each phase is L1 = 80 A, L2 = 60 A and L3 = 40 A.

• 36 A

• 40A

• 42A

• 38A

Why must electric immersion heaters in hot water cylinders have a thermal cut-out within?

• To prevent the water from freezing

• To regulate the water temperature for energy efficiency

• To prevent the water from overheating and potentially causing damage or injury

• To monitor the water level in the cylinder

List three different devices that can provide overcurrent protection.

• Fuse, Circuit Breaker, Ground Fault Circuit Interrupter

• Resistor, Capacitor, Inductor

• Transistor, Diode, Transformer

• Voltage Regulator, Amplifier, Oscillator

Explain why an IT earthing arrangement may be selected for an installation.

• It provides enhanced safety for people and equipment.

• It is the most cost-effective earthing arrangement.

• It is the only earthing arrangement allowed by regulations.

• Where unexpected disconnection of a circuit could cause danger

Explain why three-phase motor circuits do not usually include a neutral conductor.

• Because all three phases are balanced there will be no neutral current and thus a conductor is not required. 

• Due to the high cost of additional wiring for the neutral conductor.

• Neutral conductors are only omitted in single-phase circuits, not three-phase circuits.

• It is a common misconception; three-phase motor circuits always include a neutral conductor.

Answer explanation

The three phases carry the return currents of each other, eliminating the need for a neutral conductor.

List, in the correct order, the first three tests to be performed during the initial verification of a new radial final circuit in accordance with BS 7671.

• Continuity of conductors, insulation resistance, polarity

• Insulation resistance, continuity of conductors, polarity

• Polarity, insulation resistance, continuity of conductors

• Continuity of conductors, polarity, insulation resistance

Answer explanation

The correct order for the first three tests during the initial verification of a new radial final circuit in accordance with BS 7671 is Continuity of conductors, insulation resistance, polarity.