T2 - Full Exam Prep

How do you find the shape of a Magnetic Field?

A plotting compass or Iron Filings

The Henry is the unit of?

Inductance

Material that can be easily magnetised

Ferromagnetic

Factors that impact the magnitude of Voltage induced in a coil

1. The amount of Flux

2. Rate at which flux is cutting

3. The number of turns

In Flemings “Hand Rules” the thumb is the direction of?

Motion of the Conductor

Principle behind operation of a Transformer

Mutual Induction

Device designed to store electrical charge

Capacitor

Formula for charge of capacitors in parallel

Qt = Q1 + Q2 + …

Formula for charge when capacitors in series?

Qt = Q1 = Q2 = …

SI unit for frequency

Hertz

One full A.C cycle is represented on a diagram by

360 degrees Sinusoidal Waveform

Minimise condensation in conduit

Provide drainage outlet at lowest part

A running coupler is used

When neither conduit can be rotated

Continuity of metal trunking improved

By copper earth straps fitted at all joints

Purpose of segregated trunking

Accommodate low voltage and extra low voltage cable systems

For non-standard sizes of trucking, cable install shouldn’t exceed

45% trunking

Phase and neutral conductors of same circuit should be in same conduit to?

Reduce eddy currents

To prevent damage to cables, conduit install must be

Fully erected and fixed before cables installed

Arc- Quenching medium used in HBC fuse?

Silica Sand

Abbreviation that indicated Current Rating

In

The phase colours are?

1. Brown

2. Black

3. Grey

Line Voltage on 3phase supply?

400V

Voltage between 2 phases

400V

Capacitor across starter terminals in fluorescent fitting is to?

Reduce radio interference

Capacitor across incoming supply terminals in fluorescent fitting?

Improve the power factor

One function of choke in fluorescent fitting?

Produce a high voltage to strike the tube

Gas in an incandescent lamp

Argon or nitrogen

Term GLS stands for?

General Lighting Service

A non-maintained emergency lighting system is?

Only on when mains lighting fails

An emergency lighting system must provide

Lighting at a change in floor level

ETCI reg: Minimum distance flammable materials from 200W incandescent spotlight

1 metre

Functional Switch used in fluorescent lighting circuits are de-rated; meaning

The switch must operate at a lower current than its rating

If length cable halved, new resistance is?

Half

Advantage of aluminium conductors over copper?

Lighter in weight

What is the ambient temperature in the reg tables on current carrying capacity

30 degrees celcius

Minimum internal bend radius of SWA is the diameter times…

8

Second digit of IP Class is

The degree of protection against ingress of water

The additional letter in IP Classification means…

The degree of protection against contact with hazardous parts within enclosures

Type of socket used in industrial or outdoor must

Comply with IS / EN60309

The pins of 115V industrial motor plug are..

2 small and one larger round pin

Socket in Agricultural or horticultural installation must be

EN60309 states at least 0.45m above floor level.

Current is made to flow in rotor bars of a squirrel cage rotor by

Electromagnetic induction from the stator field coils

If one supply phase is open, the current in other two phases will

Increase

To rotate a 3 phase motor in opposite direction

Reverse 2 of the 3 phases

To reverse direction of capacitor start induction run motor…

Reverse either the run or start winding

Single Phase Motor “hums” but fails to start, you should test

The continuity of the stator windings

The overload unit in a D.O.L Motor circuit should be set at

The full load current of the motor

The Photovoltaic cell uses this effect to produce electricity?

Photoelectric Effect