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What is the easiest method of reversing the direction of rotation of a 3 phase induction motor controlled by star-delta starter?
Wiki User
∙ 12y ago
Just swap two of the phases over.
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Care must be taken when swapping wires on a star delta system.
Reversing the wrong set in the motor box and getting the wrong wires could accidently reverse the wrong set of windings.
This would cause the star magnetic to be rotating in the correct rotation and then when it switches to delta the motor tries to reverse causing a locked rotor condition and spiking the voltage very high and hopefully tripping the overload protection.
The correct place to swap the two legs is at the supply side of the star contactor.
Wiki User
∙ 11y ago
Wiki User
∙ 12y agouse reverse forward switch in the incoming of the starter
or go for a reverse forward star delta starter
i guess you can prepare the logic
but one thing, while the motor is rotating in one direction. one should not intiate the other direction until when the motor is stationary. unless, it'l damaage the coils
Wiki User
∙ 15y agoReverse any two leads of the supply voltage before the star delta contactor.
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What is the equation of stardelta?
The voltage of a winding that is connected in star is 1 over the square root of three, 1 / 1.732, or 0.5774, of the voltage if that winding were connected in delta. This results in a star power of 1/3, or 0.3333, of the delta power.Similarly, if you know the winding current in delta, you can calculate the star current by multiplying by 1.732.This all presumes that the neutral point of the star is symmetrically centered in the middle of the phase triangle.
Explain the necessity for the use of a starter with a dc motor?
In its simplest form, the starter of a dc motor is a variable resistance in series with the armature circuit of dc motor to reduce the high starting current so that the armature winding does not get overheated and burnt while the motor isgetting started. As the rotating armature of dc motor picks up speed, the starter resistance is gradually reduced so that the motor is able to attain its full speed when the starter is not expected to offer any additional resistance in series with the armature winding of the dc motor. At full speed the motor starts running normally, of course, without the help of starter. In other words, the starter offers resistance to armature current during starting of dc motor only. Under normal working condition of dc motor , the starter is electrically out of armature circuit of the motor. The starter protects the armature of dc motor from getting damaged. The electromotive force (emf) induced in the armature winding during starting builds up from zero value to max value to restrict the armature current within the permissible value at full speed. As the speed of armature/motor build up, armature induced emf also starts building thus reducing the role resistance offered by the starter, hence requiring it to gradually reduce as the motor picks up full speed.
