March 2018 Flashcards
State three human resource factors that will require monitoring during an electrical
installation project.
Number of operatives required
* Progress against schedule
* Levels of training or skills required
* Sicknesses and absences
Explain the operating principles of a wind turbine.
The wind turns the rotor-blades, which are connected to the main shaft, which spins a
generator to create electricity.
explain how the wound rotor on an AC induction motor achieves a high starting torque.
This is achieved by adding external RESISTANCES (1) to the ROTOR windings (1) via slip
rings/brushes (1)
State the three principles of space heating.
Convection
Conduction
Radiation.
Describe the operating principle of a thermostat in an immersion heate
It monitors water temperature (1) either directly (bi-metal) or capillary (sealed spirit or InVar
type) (1) and actuates a switch which controls the heating appliance (1).
State the earthing arrangement shown in Figure 1 and identify the parts labelled X and Y.
TN-C-S (1)
X = PEN conductor or CNE (1)
Y = Source/distributors/DNO electrode (1) –
Determine a suitable type and nominalrating of protective device for a single-phase
circuit supplying a total loading of 4000 W discharge lighting.
Calculate design current = (4000/230) x 1.8 (1) = 31.30 A (1)
Select protective device rating = 32 A (1) Type C (1)
State the two methods used to determine the suitability of a protective conductor
CSA for thermal constraints during earth fault conditions as given in BS 7671.
Adiabatic equation ݏ ൌ √ࡵࢀ
(1)
State three non-statutory publications associated with the Initial Verification of
electrical installations.
BS 7671
Guidance Note 3 (GN3)
HSE GS38
On-site Guide (OSG)
Explain the purpose of a polarity test on a lighting circuit having LED luminaires.
To confirm all protective device (1) and single pole control devices (1) are in the line
conductor only (1).
Describe three behaviours that would help maintain good relationships with the client
during the commissioning process.
Personal appearance and hygiene is important – remember, you are representing your
company.
Keep to appointment times.
Show a positive attitude and good company image at all times.
State three health and safety considerations that would contribute to a risk
assessment before carrying out fault diagnosis work.
Safe use of tools and equipment
Safe and correct use of measuring instruments
Provision and use of PPE
State three common examples of activities that can result in a short circuit.
Damage to cable, e.g. nail/screw in wall
Loose lamp holder leading to twisting of cables
Element in a lamp fusing
Explain the fundamentalrule of basic protection.
Insulation and/or barriers (1) prevent contact with parts (1) intended to be live in normal
operation (1).
Define an exposed-conductive-part
Conductive part of an electrical system (1) which can be touched and which is not normally
live (1), but which can become live under fault conditions (1).
