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That is the star point contactor that opens when it goes into the delta configuration.
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∙ 15y ago
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How can a dlta connected motor be converted in star?
If the motor terminal has six terminals in the terminal box, then it can be connected either in delta or star. If there are only 3 terminal wires then the motor can not be connected in star.(it means that the motor is designed to be connected in delta only)
Star delta starter for 3 phase induction motor?
how will you start 3phase inuction motor using star delta stater
How does a star winding shifts to a delta winding in a three phase motor?
u can change in the terminal box..
What is wye-delta motor control?
It is a type of starter that allows a motor to be started across the line by starting the motor with a reduced inrush current. The motor is started in a wye configuration until it gets up to speed and then a timer drops the wye contactor out a draws the delta configured contactor in. The motor then operates in a delta wired configuration.
What is the advantage of a Star Delta Motor Starter?
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.
How can you wire a 6-pole isolator to disconnect a 6-wire star delta motor away from the mcc and near to the motor?
There is no need to place a 6 pole disconnect to isolate the motor in the field. The motor's leads at the motor's terminal box have to be wired for a delta connection. The star delta contactor in the MCC only has three wires on its output. Six wires do not have to be taken directly to the motor. The voltage is reduced at the start of the circuit when the starter in in the star configuration. From the star configuration it changes to the delta configuration. So as you can see only a three pole isolation switch is needed in the field to isolate the motor from its supply.
In a star-delta starter what could be the problem if the motor does not rotate in star but rotates in delta?
One of the three phase contacts in the star contactor could be burned open or just open not allowing the motor to start because of a single phase condition. The time interval between star and delta connections could be small enough that the motor heaters will not catch the single phase condition and trip. When the motor goes into delta (which is now across the line starting) all of the three phase contacts in the contactor close and the motor starts.
What are the application of a automatic star delta starters?
In star, the phase voltage across a motor winding is 1/sqrt(3) of what it will be in delta (or 58%). This reduces the initial power of the motor to 58% of its' rated power, but it also decreases the starting current significantly (for a soft start). The application of this is whenever this is a desirable or acceptable feature. In most, the motor is first started, then load is put on it after it is switched to delta.
Why star delta starter is more efficient?
The star-delta starter allows the motor to start with one third its normal power, minimizing inrush current and heating, thus extending the life of the motor and its control center. When a motor is connected in star the total output torque is only a third of the total torque that could be produced running in delta. Please see related questions and links.
Why is the automatic star to delta starter tripping?
The only thing that will trip the starter, is the load of the motor. Check the motor leads to make sure you have not crossed them over coming from the motor junction box. If the motor current is normal nameplate full load amps when run across the line then reduce the timing of the timer on the switch over from star to delta.
Why does star connected motor run at less amps?
In star, a motor is connected with 415V across 2 phases, which means Line voltage is 240V (415 / 1.7ish) In delta theres 415 across each phase, therefore I = much higher according to Ohms law (I = V/R) Hypothetically; load of 24ohms connected on the motor In star; I = 240 / 24 = 10A In delta I = 415 / 24 = 17.2A Hope this helps a little
What is Full load current for 40 HP star delta motor?
What is the continuous current of 10HP star delta motor
