Answer ALL questions. Look for any feedback given if you get an answer incorrect. Keep choosing an answer until you get it correct. CORRECT or INCORRECT answers are indicated at the TOP of the page. A score is given at the TOP of the page when the exercise has been completed.
What is a standard generating voltage in a power station ?
25kV
50kV
132kV
66kV
What is the transmission voltage for the 'SUPERGRID' ?
132kV
400kV / 275kV
33kV
11kV
What is the harmful waste product released from a fossil fuelled power station into the atmosphere ?
Sulphur Dioxide
Sulphur
Sulphur Monoxide
Sulphates
What is the typical voltage utilized by 'light to heavy industry' ?
11kV
400v
230v
25kV
What is the transformer arrangement for final distribution on a housing estate ?
DELTA
STAR
STAR/DELTA
DELTA/STAR
What are the standard voltages available from a DELTA/STAR configurated transformer with 11kV primary voltage to 400v secondary ?
400v only
400/230v
11kV
11kV/400v
What is the 'cylinder' shown on the pole here ?
Transformer
Circuit Breaker
Distribution Center
Maintenance Isolator
When measuring a voltage in a circuit, how should the voltmeter be connected ?
In series
In parallel
In either series or parallel
None of these answers
When measuring a current in a circuit, how should the instrument be connected ?
In series
In parallel
In either series or parallel
None of these answers
What instrument is used for measuring CURRENT ?
Ohmmeter
Potential Difference meter
Ammeter
Wattmeter
What is a major advantage of AC over DC ?
The ease with which the AC voltage levels can be changed using transformers
Losses are less
It costs less
Cables can be smaller
What does the abbreviation AC mean ?
Alternating Current
Attenuated Current
Actual Current
Amplitude Current
What TWO main losses are found in transformers ?
EDDY and Hysteresis
Copper and Iron
Current and Voltage
Heat and Magnetism
In transformers, what type of loss is due to the small internal resistance of the windings ?
Hysteresis loss
copper loss
EDDY current loss
magnetic loss
How are EDDY current losses reduced in a transformer ?
laminating the core
use thinner conductors in the windings
use the transformer on DC only
Use Iron/Steel cores
What is the MAIN danger with AUTO-Transformers ?
They operate automatically and cannot easily be controlled
They can introduce the primary voltage onto the secondary output terminals during short-circuit
They are used where there is a large difference between the priumary and secondary voltages
They are usually very large and difficult to install
Which losses in a transformer can be reduced if the core material is carefully chosen ?
Iron losses
hysteresis losses
EDDY current losses
Copper losses
Which losses make up IRON LOSSES ?
EDDY and hysteresis
EDDY and copper
EDDY and IRON
Copper and hysteresis
What cooling medium is often used to cool Large Power transformers ?
Water
Oil
Air
No cooling required
As a general rule, if a transformer has FEWER windings on the secondary then primary, and the PRIMARY voltage is HIGH, what voltage level would be expected on the SECONDARY ?
LOWER
HIGHER
NO DIFFERENCE
FLUCTUATING OUTPUT
What is indicated by the arrow in this diagram ?
lines of magnetic flux
current flow
North and South
Lines of force
If a transformer has 60v V1, 1000 turns N1 and 150 turns N2, what is the output voltage V2 ?
9v
90v
0.9v
9.9v
If a transformer has 10A secondary current, 60 turns primary and 300 turns secondary, what is the primary current ?
50A
10A
0.5A
5.5A
If a transformer has 50A primary, 60 turns primary and 300 turns secondary, what is the secondary current ?
10A
50A
0.5A
5.5A
What is the direction of current flow in the conductor shown here ?
toward you
away from you
left
right
What is the direction of current flow in the conductor shown here ?
Away from you
Towards you
Left
Right
What is the voltage level for SELV transformer ?
Less then 50v AC
Between 50v and 230v AC
Less then 120v AC
less than 25v AC
What is meant by VA with regard to transformers ?
it is the total rating for the transformer
it is the primary voltage and Secondary current
It is the Secondary voltage and Primary current
It is both Primary voltages and Secondary currents for the transformer
What does the 'S' in SELV (Separated Extra Low Voltage) refer to, with regard to transformers ?
It means that there is NO earth on the secondary, in relation to the earth on the primary
It means that there are separate lives on the transformer
It means that there is separation between the windings
It means that there is a separate voltage between primary and secondary
In a SERIES circuit, if the SUPPLY voltage is 10v, and there are THREE different value resistances in the circuit, what can be said about the voltage drops across these resistances ?
They will total 10v
They will total HALF of the supply voltage
They will total 3X the supply voltage
10v will drop across each resistance
In a PARALLEL circuit, if the SUPPLY voltage is 10v, and there are THREE different value resistances in parallel in the circuit, what can be said about the voltages across each resistance ?
They will be 10v also
They will equal HALF of the supply voltage
They will total 3X the supply voltage
10v will divide EQUALLY across the THREE resistances
In a PARALLEL circuit, if the SUPPLY current is 10A, and there are THREE different value resistances in parallel in the circuit, what can be said about the current through these resistances ?
They will equal the supply current of 10A
They will equal HALF of the supply voltage
They will total 3X the supply voltage
They will divide equally across the THREE resistances
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