1. The iron loss in a 100 kVA transformer is 1 kW and the full load copper losses are 2 kW, then the maximum efficiency occurs at a load of:
a) 141.4 kva
b) 70.7 kva
c) 50 kva
d) 70.7 kw
2. In a transformer, iron core is provided in order to:
a) Reduce the magnetic path reluctance
b) Reduce eddy current and hysteresis losses
c) providing the coupling between primary and secondary winding
d) Increase the magnetizing current
3. The transformer efficiency under heavy loads is comparitively low due to:
a) Large increase in copper losses
b) Drop in the power factor drastically
c) Both (a) and (b)
d) None of the above
4. In a transformer:
a) Both open circuit (O.C) and short circuit (S.C) tests are conducted on LV side
b) open circuit (O.C) test is conducted on LV side and Short Circuit (S.C) test is conducted on HV side
c) open circuit (O.C) test is conducted on HV side and Short Circuit (S.C) test is conducted on LV side
d) Both open circuit (O.C) test and Short Circuit (S.C) test are conducted on HV side
5. The size of the transformer core depends on the:
a) Frequency
b) Permissible flux density in the core
c) Area of the core
d) All the above
6. Distribution transformers are designed to have maximum efficiency at:
a) At full load
b) Half load
c) No load
d) At almost 80% of the laod
7. The use of high flux density in the design of the transformer:
a) Reduces the eddy current losses
b) Reduces the weigh per kva output
c) Reduces the copper loss
d) Distorts the sinusoidal wave shape phenomenon
8. Natural air cooling is used for the transformers of the rating upto:
a) 100 kva
b) 500 kva
c) 5-10 kva
d) 1 MVA
a) 141.4 kva
b) 70.7 kva
c) 50 kva
d) 70.7 kw
2. In a transformer, iron core is provided in order to:
a) Reduce the magnetic path reluctance
b) Reduce eddy current and hysteresis losses
c) providing the coupling between primary and secondary winding
d) Increase the magnetizing current
3. The transformer efficiency under heavy loads is comparitively low due to:
a) Large increase in copper losses
b) Drop in the power factor drastically
c) Both (a) and (b)
d) None of the above
4. In a transformer:
a) Both open circuit (O.C) and short circuit (S.C) tests are conducted on LV side
b) open circuit (O.C) test is conducted on LV side and Short Circuit (S.C) test is conducted on HV side
c) open circuit (O.C) test is conducted on HV side and Short Circuit (S.C) test is conducted on LV side
d) Both open circuit (O.C) test and Short Circuit (S.C) test are conducted on HV side
5. The size of the transformer core depends on the:
a) Frequency
b) Permissible flux density in the core
c) Area of the core
d) All the above
6. Distribution transformers are designed to have maximum efficiency at:
a) At full load
b) Half load
c) No load
d) At almost 80% of the laod
7. The use of high flux density in the design of the transformer:
a) Reduces the eddy current losses
b) Reduces the weigh per kva output
c) Reduces the copper loss
d) Distorts the sinusoidal wave shape phenomenon
8. Natural air cooling is used for the transformers of the rating upto:
a) 100 kva
b) 500 kva
c) 5-10 kva
d) 1 MVA
