21
In a transformer the tappings are generally provided on
Answer: low voltage side
Questions
22
If the percentage impedances of the two transformers working in parallel are different, then
Answer: parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load
23
What will happen if the transformers working in parallel are not connected with regard to polarity ?
Answer: Incorrect polarity will result in dead short circuit
24
If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be
Answer: R2IK2
25
Two transformers operating in parallel will share the load depending upon their
Answer: per unit impedance
27
The purpose of providing iron core in a step-up transformer is
Answer: to decrease the magnitude of mag-netizing current
28
Greater the secondary leakage flux
Answer: less will be the secondary induced e.m.f.
29
Spacers are provided between adjacent coils
Answer: to provide free passage to the cooling oil
30
No-load current of a transformer has
Answer: has small magnitude and low power factor
32
The maximum efficiency of a distribution transformer is
Answer: at 50% full load
33
Power transformers are designed to have maximum efficiency at
Answer: nearly full load
34
Natural oil cooling is used for transformers up to a rating of
Answer: 3000 kVA
35
In the transformer the function of a conservator is to
Answer: protect the transformer from damage when oil expends due to heating
37
The no load current in a transformer lags behind the applied voltage by an angle of about
Answer: 75°
39
In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are
Answer: hysteresis and eddy current losses
