81
A shell-type transformer has
Answer: reduced magnetic leakage
Questions
82
N atural air coo ling is generally restricted for transformers up to
Answer: 1.5 MVA
84
The secondary winding of which of the following transformers is always kept closed ?
Answer: Current transformer
85
The function of breather in a transformer is
Answer: to arrest flow of moisture when outside air enters the transformer
86
The transformer oil should have _____ volatility and _____ viscosity.
Answer: low,low
87
For the parallel operation of single phase transformers it is necessary that they should have
Answer: same polarity
88
Short circuit test on transformers is conducted to determine
Answer: copper losses
89
Open circuit test on transformers is conducted to determine
Answer: core losses
90
During open circuit test of a transformer
Answer: primary is supplied rated voltage
91
Which type of winding is used in 3phase shell-type transformer ?
Answer: Sandwich type
92
The transformer laminations are insulated from each other by
Answer: thin coat of varnish
93
When secondary of a current transformer is open-circuited its iron core will be
Answer: hot because of heavy iron losses taking place in it due to high flux density
94
Iron loss of a transformer can be measured by
Answer: low power factor wattmeter
95
Negative voltage regulation is indicative that the load is
Answer: capacitive only
96
If the supply frequency to the transformer is increased,”the iron loss will
Answer: increase
97
An ideal transformer will have maximum efficiency at a load such that
Answer: copper loss = iron loss
98
In an actual transformer the iron loss remains practically constant from noload to fullload because
Answer: core flux remains practically constant
99
When a given transformer is run at its rated voltage but reduced frequency, its
Answer: core flux density is increased
100
An ideal transformer is one which has
Answer: no losses and magnetic leakage
