open, closed, semi-open

open, closed, semi-enclosed

round, square, triangular

none of these

increase the insulation of the windings

make the windings vibrationless

provide an additional insulation layer on the windings

all the three stated above

for short-circuit test only

for open-circuit test only

For 'earth' fault test only

for all the three above stated tests

open-circuited

short-circuited

independent

nothing of these

active side

inactive side

coil lead

unuseful side