Electrical Protection 4

Electrical cordination is provided when the protective device _______ ______ the fault is activated

• closest to

• farthest from

Which of the following electrical faults do we not need to provide protection for

• short circuits

• overcurrent

• open circuit

• earth leakage

Which type of circuit breaker will operate between 3 and 5 times the circuit breaker current rating

• Type A

• Type B

• Type C

• Type D

What type of energy may be dissapated as a result of a short circuit

• Sound energy

• Electromechanical energy

• Light energy

• Chemical energy

The rated current of a fuse is the _________ current a protective device can carry cotinuously without deterioration

• short circuit

• maximum

• minimum

• leakage

________ ________ is the maximum current that a circuit breaker or fuse can safely interupt.

• Category of duty

• Breaking capacity

Which one of the following is a reason why rewireable (SERF) fuses are no longer permitted to be used for new installations

• They are expensive to replace

• They do not comply with the regulations for safety reasons

• They are not as aesthetically pleasing as other types of fuses

• The PSCC rating of the fuses exceeds the capability of the power network

Close excess current protection is .............

• The maximum current a device can carry continuously without deterioration

• The maximum fault current that a protective device can safely stop flowing

• protection that will operate within 4 hours at 1.5 times the designed load current of the circuit it protects

• a rating used to show the type of voltage and the rupturing/breaking capacity of a fuse

What form of energy may be dissapated as a result of a short circuit fault

• Heat energy

• Chemical energy

• Light energy

• Sound energy

What description best describes a SERF protection device

• Thermal and magnetic operating devices are housed in a sealed plastice case

• Silver fuse element surrounded by a filler and enclosed in a ceramic body

• Electronic monitoring circuits housed in a sealed plastic case

• Consists of an alloy wire containg 63% tin and 37% lead and having a circular section held in a ceramic body