Stephen Smith AC concepts review 3

20 terms by StephenSmith Teacher

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Step up transformers

increase the voltage in the secondary winding, when compared to the primary winding

Step down transformers

Decrease the voltage in the secondary winding, compared to the primary winding

The transformer ratio of a transformer with primary voltage of 240v and a secondary voltage of 40 v is

6 to 1

The transformer ratio of a transformer with primary turns of 500 and secondary turns of 1250

1 to 2.5

The secondary current will

be increased by four times

A danger tag placed on an electrical isolation device, may only be removed by

The person who placed it

The steps to isolate an electrical circuit are

Inform the customer, Identify the isolation device, Isolate the circuit, discharge stored energy, verify isolation, bond load side conductors to earth

The checks to be made before reconnecting supply to a circuit are

Check circuit continuity, check conductor terminal location, check terminal condition, check conductor condition, check circuit insulation resistance, check earth loop impedance.

The limited electrical licence of a refrigeration tradesperson allows him/her to complete the following work.

service and maintenance procedures on electrical circuits directly connected to refrigeration and air conditioning equipment, only.

Calculate the secondary current of a transformer with a ratio of 12 to 1 and a primary current of 10 amps.

120 amps

Determine the secondary power consumed by a transformer that consumes 800 watts in the primary coil.

800 watts

The secondary voltage being 20v.

120 amps

Secondary power 480 watts.

4 amps

Three types of circuit diagram are

schematic, wiring, block

Two sections of an electric circuit are

Control and power circuits

Two methods of connecting circuit components are

Series and parallel

Circuit loads are usually connected in parallel to ensure that

All loads are connected to full supply voltage

Switches in control circuits are commonly connected in series to ensure that

when any switch becomes open circuit, supply to the circuit load is disconnected.

Circuit loads are not connected in series because

Voltage drops across each circuit load in series, preventing loads from being connected to full supply voltage.

In a parallel circuit having 2 branches, load number 2 has a volt drop of 238 volts. Determine the supply voltage?

238 volts

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