Since the starting winding of the split-phase motor has high resistance, it heats up quickly. Split-phase induction motors are suitable for the applications where the starting period is small. Split-phase induction motors are less expensive, thus, they are very popular motors in the market. The maximum or pull out torque is about 2.5 times of the full-load torque at about 75% of synchronous speed. The starting torque of a split-phase induction motor is about 1.5 times of the full-load torque.
SINGLE PHASE MOTOR WINDING RESISTANCE CHART FULL
The split-phase motor has the starting current about 7 to 8 times of the full load current. The characteristics of split-phase induction motors are given as follows − Characteristics of Split-Phase Induction Motor The normal speed of the motor is less than the synchronous speed and it depends upon the mechanical load on the shaft of the motor. Now, the motor operates as a single-phase induction motor and continues to accelerate till it reaches the normal speed. When the motor speed reaches about 80% of the synchronous speed, then the centrifugal switch isolates the starting winding from the circuit. Where, k is a constant of proportionality whose value depends upon the design of the machine. The starting torque of the split-phase motor is given by, As a result, a weak revolving field is produced which starts the motor.
![single phase motor winding resistance chart single phase motor winding resistance chart](https://alltestpro.com/wp-content/uploads/2021/04/all-test-pro-2-1024x455.jpg)
Therefore, the currents I s and I m in the two windings have a reasonable phase difference of about 25° to 30° between them. When the starting winding of the motor is connected to the source of single-phase AC supply, the starting winding carries a current I s while the main winding carries a current I m as shown in the connection diagram.Īs the starting winding is made highly resistive whereas the main winding highly inductive. The starting and the main windings are so designed that the starting winding (S) has a high resistance and relatively low reactance while the main winding (M) has relatively low resistance and high reactance so that the currents flowing in the two windings have reasonable phase difference (α) of about 25° to 30° as shown in the phasor diagram. The starting winding operates only during the brief period when the motor starts up.
![single phase motor winding resistance chart single phase motor winding resistance chart](https://i.ytimg.com/vi/mPkw1H9uJLo/hqdefault.jpg)
The starting winding is displaced by 90° from the main winding as shown in the figure. A split-phase induction motor is a type of single-phase induction motor in which the stator is provided with a starting or auxiliary winding (S) and a main or running winding (M).