10 hp and above motor power rating....
A motor
The transition from star connection to delta connection requires that the current flow through the motor is interrupted. This is termed "Open Transition Switching" and with an induction motor operating at partial speed (or full load speed), there is a large current and torque transient produced at the point of reconnection. This transient is far worse than any produced by the DOL starter and can cause severe damage to equipment and the supply.
A "star-delta" starter- also known as a "Y-delta" or "wye-delta" starter - is used to reduce the voltage on the motor windings to only 1/.'/'3 [one divided by root 3] times the incoming line voltage, to help reduce mechanical stress and in-rush current at start-up.More detailWhenever you start a big heavy electric motor, you need to start it slowly to prevent the rotor overheating and drawing an enormous current. When the windings of a 3-phase motor are connected in STAR the voltage is reduced to a fraction equal to one over root three (1 / 1.732) times the normal running voltage that is used when it is connected in DELTA, resulting in a reduction of nearly one half the normal current.Once the motor picks up speed, the connection is changed to DELTA so that the motor runs at full speed and torque from then on. It's a bit like using the gears of an automobile.For more information please see the answers to the Related Questions shown below.
question is incomplete, I think you ask how much current consumed by this motor. for starting this motor we need a star/delta starter and a three phase supply.
200 hp requires about 149kW
Check your Delta connections first if the phases is corresponding, and check your Circuit Breaker if it sufficiently rated.
The inrush current to the starting motor is lower due to the the motor coils being in series across the line creating a higher impeadence. When the starter connects to delta connection the motor is already turning and it does not have to go through the locked rotor phase. This system is being phased out now with the use of electronic soft starts and by-pass contactors.To start a motor direct on line (DOL) in delta requires approximately 6 to 8 times the full load current of the motor and delivers full torque. Delta places 415v across each of the windings on the motor. A Star-Delta starter starts the motor in Star which places 240v across each winding on the motor. This results in a lower starting current and also a lower starting torque.
If a motor is connected in a star configuration it will operate at a slower speed. This is the working process that a star delta starter operates on. At first through the starter the motor starts in the star connection. When the motor gets up to its highest speed in that connection it times a timer out , the star starter drops out and the delta starter pulls in and then connects the motor in the delta connection. This allows more voltage to be applied to the motor and it then speeds up to its nameplate rated RPM.
I assume a 3 phase, AC induction motor. A star delta starter or a soft starter can be used. A soft starter is better compared to a star delta starter, but it is more expensive.
The use of a star delta starter is for motor control only and not resistive heating loads. This type of starter is used to dampen the inrush current by using a lower voltage to start the motor.
The outer casing of an electric motor, as in a starter, wiper motor etc.
The outer casing of an electric motor, as in a starter, wiper motor etc.
its is very simple whem motor shifted on delta then timer will disconnect
because at the starting the induction motor drawn a heavy current thats why we use starter to increase the starting resistance of the induction motor!
Star delta starter
On a star delta starter a motor overload or a motor going to ground and cause a short circuit will cause the overload protection to trip. These overloads have to be reset before the motor can be restarted.
how will you start 3phase inuction motor using star delta stater