Month: January 2018

Motor start with split winding

For application of split winding, it is necessary for the electric motor to have two circuits in parallel per phase. Two steps are used to connect the motor to the mains, where a contactor connects part of the winding to the mains (usually half the winding) for a short time, approximately 4 seconds and another contactor connects the remainder of the winding to the mains, completing the call. This method can be used when the engine starts at a vacuum, and only after reaching the nominal speed does the other part of the winding connect, and then the load is applied and the load gradually increases with the rotation. Example: Fans, centrifugal pumps, etc.

The curves represent the conjugate x velocity of the split winding start method. The starting conjugate developed by the split winding method is admirably smaller than the direct starting conjugate, and is even smaller than the full charge conjugate. This should be an advantage when you want a soft match. In this method, the motor will accelerate the load until it is close to the rated speed, ie the load resistant torque must always be lower than the torque developed with the split winding.

Speed and Reversal of Direction of Rotation

The direction of rotation of an electric motor will depend on the direction of the magnetic field and the direction of current in the armature. If the direction of the field or current is reversed, the motor rotation will also be inverted. However, if both are reversed at the same time, the motor will continue to rotate in the same direction.

The speed of an engine is given by the number of revolutions of the shaft with respect to time and is expressed in units of revolutions per minute (RPM). A decrease in the magnetic field of the motor causes an increase in its speed and an increase in the field will cause a decrease in the speed of the motor D83075 OLP. The torque developed by a motor to move a given load depends on the current intensity that the armature requests from the power supply. The higher the load, the higher the torque and consequently the higher the current. If the load is lower, the torque will be lower and the current intensity as well. To achieve a higher torque, the motor must rotate at a slower speed, so the speed of a DC motor depends on the load coupled to the shaft.