Fault Protection 1 - Types of protective device inclu. RCD, BS numbers, discrimination, disconnection times, fusing factors, types of fault, exposed and extraneous. 14 questions from a bank of questions
Which one of the following is a 'rewirable fuse' type ?
BS3036
BS1361
BS88
BSEN60898
Which one of the following is a 'HRC' type ?
BS3036
BS1361
BS88
BSEN60898
Which one of the following is a 'cartridge fuse' type ?
BS3036
BS1362
BS88
BSEN60898
Circuit breaker protective devices use all but one of the following operational design characteristics. Which one?
thermal
magnetic
hydraulic/pneumatic
gravity
Which one of the following is termed an 'exposed conductive part'?
metallic motor housing
copper water pipe
stainless steel sink unit
cast iron drain
Which one of the following is termed an 'extraneous conductive part'?
metallic motor housing
metal socket back-box
steel consumer unit
cast iron drain
Which one of the following is not an example of an 'overload fault'?
too many appliances plugged into a 4-way socket adaptor
incorrect termination of conductors
large machines (motors) starting up
insulation failure in a circuit
Which one of the following is not an example of an 'short-circuit fault'?
incorrect conductor terminations (L to E for example)
severing live conductors with cable cutters
large machines (motors) starting up
insulation failure in a circuit
Which one of the following is not an example of an 'Earth fault'?
incorrect conductor terminations (L to E for example)
severing live conductors with cable cutters
extra loading onto an existing circuit
insulation failure in a circuit
Large circuit breaker protective devices use which one of the following operational design characteristics to either vastly increase the operating time or delay the operational time. Which one?
thermal
magnetic
hydraulic/pneumatic
gravity
Which fuse design is especially suited to 'high start-up currents' because of its good 'discrimination'?
HRC/HBC
semi-enclosed
cartridge type
none of these
What colour is a 30A BS3036 fuse?
blue
red
yellow
green
'discrimination' ensures that protective devices nearest the fault operate before other protective devices. If a BS3036 fuse is rated at 15A and has a 'fusing factor' = 2. At what current level should the fuse operate?
15A
30A
17A
13A
what is 'fusing factor' with regard to protective devices?
fusing current/device rating
device rating x fusing current
fusing current - device rating
device rating + fusing current
what is a RCD?
residual current device
redundant circuit device
residual circuit device
redundant current device
What is the disconnection time for portable equipment rated at under 32A, supplied by socket-outlet on a TN Supply system?
0.2 seconds
0.4 seconds
5 seconds
10 seconds
Which one of the following best describes the operation of a RCD?
thermal
magnetic
hydraulic
current balance
What is an RCBO?
a combined circuit breaker and RCD
a high current RCD
a time delayed Circuit breaker
a special earth fault device
What is the disconnection time for fixed equipment rated at over 32A, installed on a TN Supply system?
0.2 seconds
5 seconds
0.4 seconds
10 seconds
What is the disconnection time for portable equipment rated at under 63A, supplied by socket-outlet on a TT Supply system?
0.4 seconds
0.2 seconds
5 seconds
10 seconds
What is meant by the abbreviation 'HRC' when referring to the HRC fuse?