THEORY - TRANSFORMERS | 2025/2026 UPDATE |
QUESTIONS AND ANSWERS | 100% CORRECT
How many windings does an 11kV/400V, Delta/Star transformer have? Answer
- - Six
What happens with the voltage on the secondary side of an 11kV/400V
Delta/Star transformer, if you reduce the tappings (windings) on the primary
side? Answer - - Increase
What is the expected secondary voltage for a voltage (potential) transformer?
Answer - - 110V
What is the expected currents for a current tranfromer? Answer - - 1A & 5A
Explain why there should be no fuses on the secondary of the current
transformer Answer - - If open circuited, high voltages may be present causing
hazard of electric shock and possible damage to the CT windings
- Damage to the CT
What does the term burden mean when looking at CT's? Answer - - It's the
load (amp meter and leads) connected to the CT
Eddy Current Loss and Hysteresis Loss are collectively known as Answer - - Iron
losses
, When transformer windings are carrying current, they heat up. This heating is a
loss of energy. What is this loss of energy known as? Answer - - Copper Loss
How is the core of the transformer manufactured to reduce eddy currents?
Answer - - Laminated plates
How is the core of the transformer manufactured to reduce Hysteresis? Answer
- - Use silicon steel
Why is a transformer rated in kVA and not kW? Answer - - The rating of every
transformer is always given in VA or kVA, which is related to the voltage in the
windings
Which protective device will shut down a transformer in the event of an
internal loose connection or arcing, causing gas generation inside the
transformer? Answer - - Buchholz relay
What is Hysteresis energy loss due to? Answer - - The magnetising and
demagnetising of the core of a transformer
What are Eddy currents and Hysteresis losses collectively known as? Answer - -
Iron losses
What are currents induced into the core of a transformer known as? Answer - -
Eddy currents
What is the burden of a current transformer? Answer - - The lead and Amp
meter connected to the CT
QUESTIONS AND ANSWERS | 100% CORRECT
How many windings does an 11kV/400V, Delta/Star transformer have? Answer
- - Six
What happens with the voltage on the secondary side of an 11kV/400V
Delta/Star transformer, if you reduce the tappings (windings) on the primary
side? Answer - - Increase
What is the expected secondary voltage for a voltage (potential) transformer?
Answer - - 110V
What is the expected currents for a current tranfromer? Answer - - 1A & 5A
Explain why there should be no fuses on the secondary of the current
transformer Answer - - If open circuited, high voltages may be present causing
hazard of electric shock and possible damage to the CT windings
- Damage to the CT
What does the term burden mean when looking at CT's? Answer - - It's the
load (amp meter and leads) connected to the CT
Eddy Current Loss and Hysteresis Loss are collectively known as Answer - - Iron
losses
, When transformer windings are carrying current, they heat up. This heating is a
loss of energy. What is this loss of energy known as? Answer - - Copper Loss
How is the core of the transformer manufactured to reduce eddy currents?
Answer - - Laminated plates
How is the core of the transformer manufactured to reduce Hysteresis? Answer
- - Use silicon steel
Why is a transformer rated in kVA and not kW? Answer - - The rating of every
transformer is always given in VA or kVA, which is related to the voltage in the
windings
Which protective device will shut down a transformer in the event of an
internal loose connection or arcing, causing gas generation inside the
transformer? Answer - - Buchholz relay
What is Hysteresis energy loss due to? Answer - - The magnetising and
demagnetising of the core of a transformer
What are Eddy currents and Hysteresis losses collectively known as? Answer - -
Iron losses
What are currents induced into the core of a transformer known as? Answer - -
Eddy currents
What is the burden of a current transformer? Answer - - The lead and Amp
meter connected to the CT
