WorksheetsUNIT 3:TRANSFORMERS
Total questions: 10
Worksheet time: 5mins
A transformer works on the principle of:
Coulomb’s law
Mutual induction
Self-induction
Ohm’s law
EMF induced in transformer windings is due to:
Current only
Voltage only
Rate of change of flux
Mechanical rotation
EMF equation of transformer:
E = 2.22 f N Φm
E = 4.44 f N Φm
E = I²R
E = V/Z
Equivalent circuit of a transformer represents:
Copper losses
Core losses
All electrical behavior using R and X
Only magnetizing current
Core losses include:
Hysteresis and eddy current losses
Copper losses
Dielectric losses
Mechanical losses
Copper losses depend on:
Voltage
Flux
I²R
Frequency
Voltage regulation is:
(VNL – VFL) / VFL
V/I
Efficiency × 100
Core loss – full load loss
Maximum efficiency occurs when:
Iron loss = Copper loss
Full load
Voltage maximum
Frequency minimum
Transformers are rated in:
W
VAR
kVA
Amps
Transformer is used to:
Change frequency
Change power
Change voltage and current levels
Convert AC to DC
