Answer / sayan

The pinciple of a star dela starting is based on the fact
of reduction of the starting current at the time of
starting of the motor. But there is always a surge of
current whenever there is a transition from star to delta.
This is essentially useful for the motors which are
connected to systems which are prone to have a voltage dip
at the starting of the motor.But the only disadvantage of a
star delta starter is that the starting torque reduces
appreciably during starting the motor in star.

Answer / shyam prakash ray

The principal is to keep the starting current in safe limit
so that the motor achieves 70% of speed as connected to
star side, since the motor draws very high current at the
time of starting due to high starting torque.

Once the motor gets started then it is changed/converted
into delta side either manually or automatically for
running.

Answer / ravinder kashyap

work of a starter is reducing high starting current
in star connection voltage is Vph=Vl/root 3
so at starting time of motor we are use star connection at
starting star connection are use then after picking normal
speed after this delta connection are applied to motor
this is the principle that by use of star /delta voltage
conversion scheme

Answer / amit vishwakarma

Star delta starter used for squirrel cage motor,utilises the principle of reducing the starting voltage.all the six terminals( each of two) of 3 phase induction motor are brought to the starter ......
             In fact start delta starter is simply a two way switch. The method is based upon the principle that with 3- winding  connect in star, the voltage across each winding is 1/√3..i.e.57.7% of the line to line voltage whereas, the same winding connected in delta will have full line to line voltage across each.
     The star delta starter connects three stator winding in star across the rate supply voltage at the starting instant. After the motor attain speed, the same winding through a change over switch are connected in delta across the same supply voltage..

Answer / guru

TO REDUCE THE STARTING CURRENT FOR SERIES MOTORS.

Answer / ernest parku

Star is to reduced the high starting torque of the motor or the high surge current to a full load of delta connection.

Answer / ganesh ghule

The pinciple of a star dela starting is based on the fact
of reduction of the starting current at the time of
starting of the motor.

Answer / guna sekhar

induction motor draws 4times the load current of motor intially. so we use star -delta starter to reduce intial current . first the windings connected in star thereby reduces the intial current by 1/../3[root3].after certain time delay its converts winding connection to delta.

Answer / ketan

Reduction starting curernt because of current is devided in
phase 60%.

what is PWM in IGBT and how it works for drive.?

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