Wound Rotor Speed Control
A time operated controller circuit is shown in Figure 44 – 8. In this circuit, four steps of speed control are possible. Four separate push buttons permit selection of the operating speed of the motor. If any speed other than the lowest speed or first speed is selected, the motor will accelerate through each step with a 3 second time delay between each step. If the motor is operating at a low speed and a higher speed is selected, the motor
will immediately increase to the next speed if it has been operating in its present speed for more than 3 seconds. Assume for example, that the motor has been operating in the second speed for more than 3 seconds. If the fourth speed is selected, the motor will immediately increase to the third speed and 3 seconds later increase to the fourth speed. If the motor is operating and a lower speed is selected, it will immediately decrease to the lower speed without time delay.