Basic Circuits Flashcards
What are the 2 low voltage DC electrical circuits types?
Two wire system (insulated return)
Earth return circuit (chassis/ frame return)
Advantages and disadvantages of two wire system?
Advantages - minimise risk of fire or explosion
Disadvantages - costly, extra weight, harder to fault find
Advantages and disadvantages of earth return circuit?
Advantages - less costly, lighter and easier to fault find
Disadvantages - higher risk of sparking causing explosion or fire
What do simplified circuits comprise of?
Component
Switch
Three wires - feed, switch line, return
What colour is feed wire?
Single colour
What colour is switch line?
Same as feed wire colour plus a tracer of another colour
What colour is the return wire?
Often black
What is a battery?
A portable DC electrical supply
What is a conductor?
A material of extremely low resistance, which freely allows a flow of electrical current when a voltage is applied
What are the types of fuse?
Paper cartridge Domestic plus top Flat bladed Ceramic body Rewire-able
How is an ammeter connected? And what resistance dose it have?
Series
Low resistance
How is a voltmeter connected and what resistance dose it have?
Parallel
High resistance
What are the 3 most common faults in a circuit?
Open circuit
Short circuit
High resistance fault condition
What can an open circuit be caused by?
Ruptured fuse
Fractured cable
Component failure
What can a high resistance fault be caused by?
Loose connection
Terminal corrosion
Dirty /oxidised switch contacts
Defective components
What is earthing for?
To provide a low resistance path for fault currents to travel
What is continuity?
A continual uninterrupted link between two electrical conductors
What is resistance?
The opposition to current flow in an electrical circuit
What do you set your multi meter to when testing continuity?
Ohms
What is continuity?
A continual uninterrupted link between 2 electrical conductors
You test a switch in the off position, what would you expect?
O/L
What Is important to remember about halogen lamps?
The glass should not be touched
What is electrical bonding?
Joining of all metal frames to chassis of equipment
When carrying out continuity checks on cables, what should the meter be set to?
Ohms
