3005 MEN, SELV, PELV Electrical Protection 1

What is not one of the 3 main categories of faults that we need to protect for?

• Earth Leakage faults

• Over current

• Under current

• short circuits

Current finds a path of very little ________ which leads to high current.

• Inductance

• Current

• Capacitance

• Resistance

Over current is defined as ........

• Current that is bigger than the rated current of the equipment

• Current that exceeds the rating of a standard 10 amp socket oulet

• As per As/NZS3000 2007 2.4.3.1 any current exceeding 63 amps

• Current that is more than that defined in AS/NZS 3000: 2007 4.2.1 (a)

Earth leakage current is defined as .......

• A small amount of voltage that is lost or leaked to earth

• A level of current that can be detected by an RCD

• The standing leakage current from induction motors

• A small amount of current that is lost or leaked to earth

The maximum disconnection time (230/400 supply voltage) in the event of a fault shall not exceed ___ seconds for hand held electrical equipment.

• 0.3

• 0.4

• 0.5

• 5

What problem does earth leakage current not cause?

• Reduces the efficiency of the installation due to lost energy

• Reduces the safety factor and increases the chance of an electric shock

• Causes nuisance tripping of MCB's

• Could cause a fire in flammable situations

Electrical faults can cause more _______ to flow than the system was designed for.

• Current

• Voltage

• Electrons

• Resistance

Electromechanical energy is when electrical energy is converted into __________ energy

• Electrical

• Heat

• Kinetic

• Mechanical

With electric shocks the effect (damage caused) to the body will depend on the size of _________ and time that it flows

• voltage

• current

• MCB

• capacitor

Disconnection times of up to 5 seconds are permitted for circuits not directly supplying portable equipment or hand-held equipment because:

• Faults in such circuits are more likely

• There is more likelihood of being in contact with equipment during a fault

• Equipment is usually not gripped and can be released easily

• Touch voltages are expected to exceed the time/touch voltage relationship