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Frequency does not change in transformer
Spacers are provided between adjacent coil to provide free passage
to the cooling oil
In given transformer for given applied voltage, losses which remain
constant irrespective of load changes are Hysteresis and eddy
current losses
No load current of a transformer has small magnitude and low
power factor
Primary winding of transformer can either be low voltage or high
voltage winding
Open circuit test on transformer is conducted to determine core
losses
High voltage winding in a transformer has more number of turns
Short circuit test on transformer is conducted to determine Copper
losses
In transformer the energy is transfer from primary to secondary by
the flux
The transformer rating are usually expressed in terms of kVA
Power transformer are designed to have maximum efficiency at
nearly full load
In the transformer low voltage winding has got more cross
sectional area
Losses which occur in rotating electric machines and do not occurs
in transformer are Friction and Windage losses
The noise resulting from vibrations of laminations set by magnetic
forces, is termed as hum
The purpose of laminations of transformer core is reduce eddy
current losses
The chemical used in breather is silica gel
Two transformers operating in parallel will share the load
depending upon per unit impedance
An ideal transformer will have maximum efficiency at a load such
that Copper loss is equal to iron loss
A transformer cannot raise or lower the voltage of a DC supply
because the rate of change of flux is zero
The transformer laminations are insulated from each other by thin
coat of varnish
The path of magnetic flux in a transformer should have low
reluctance
Core saturation is the most likely source of harmonics in a
transformer
The no load current in a transformer lags behind the applied
voltage by an angle of about 75 degree
While conducting short circuit test on a transformer, low voltage
side is short circuited
The use of higher flux density in the transformer design to reduces
weight per kVA
The efficiency of two identical transformers under load conditions
can be determined by back to back test
Sumpners test is conducted on transformer to determine
temperature
Silicon steel used in laminations mainly reduces hysteresis loss
A common method of cooling a power transformer is oil cooling
The degree of mechanical vibrations produced by the laminations
of a transformer depends on
1
...
Gauge of laminations
3