what is star delta connection in a electric motor give full detail?

Answer 1

When an induction motor is started directly on line, it takes a starting current 6(six) times the full load current. For large motor the high starting current causes voltage drop in the
power system which may trip other motors in the systems. The utility companies restrict the rating of the motor which can be started directly on line.

To reduce the starting current of an induction motor the voltage across the motor need to be reduced. This can be done by autotransformer starter, star-delta starter or resistor starter. Now-a-days VVVF drive used extensively for speed control serves this purpose also.

For star-delta connection the motor windings are connected in star during starting. The connection is changed to delta when the motor starts running. The starting current and starting torque of DOL started and start-delta connected motors are as follows:

Starting method Starting current Starting Torque

DOL 6I 2T

Star-delta (1/root3)^2x6I (1/root3)^2x2T

=2I =2T/3
Thus it can be seen that the starting current and starting torque are both reduced. The motor should be capable to start at such reduced torque with load.

Answer 2

Star Delta Connection

Answer 3

Star delta connection is a connection used to minimize the starting curent of a motor let say you have a motor supplied from 3 phase 400 volt source

at the start let the motor connection a star if you draw it you'll notice that the motor winding get the voltage divided by 1.73
which mean each winding will be supplied by 230V

by using PLC systems after a dely the connection will change to delta so each winding will be supplied by a full phase voltage which is 400V

Answer 4

Look up transformer that is Delta connected.

Answer 5

star delta only used 3 phase 400v source.

Answer 6

it's the wiring and starting configuration that's star or delta, not the motor