Since the coasting time may be unacceptable, particularly in an emergency situation, electric braking can be used to provide a more immediate stop. By applying a DC voltage to the stationary windings once the AC is removed, a magnetic field is created in the stator that will not change polarity.
How do you make an electric motor stop at a certain point?
instead, using simple relay logic, electrically isolate motor and then connect low value, power resistor parallel to the motor to brake it. This arrangement will bring motor gently to stop without any mechanical arrangement.
How do you slow down a motor?
Most DC motors can be slowed down by reducing the supply level of power, Volts, lower volts and resulting less amps, will create less electrical field and will slow motor down. For more gradual speed control there are electronic solutions that are called PWM (Pulse Width Modulation) controllers or Mosfet H bridges.
Which of the following is a disadvantage of plugging a motor?
Another drawback to plugging is that it can induce high mechanical shock loads on the motor and connected equipment, due to the abrupt stop that it causes. Plugging is also a very inefficient method of stopping and, therefore, generates significant heat.
Which is the best braking method?
Explanation: Plugging is the best braking method among all braking techniques. In plugging the value of the armature current reverses and the mechanical energy is extracted. A very high braking torque is produced in case of plugging.
How do you start an electric motor?
AC commutator motors may be started by applying a reduced voltage or by shifting the brushes. Both of these methods are also employed for speed control, and in most cases starting can be satisfactorily affected by adjusting the control equipment to the low-speed position and then switching on full-line voltage.
In what conditions does a DC motor stop rotating?
<7> If you pinch the shaft with greater force than you did when using a single battery, the motor still keeps rotating. You would need to apply more pressure to stop the motor by pinching the shaft.
How do you reduce the rpm of an electric motor?
The load to be driven by the shaft will often require a different speed or torque or will require the transmission of power to an adjacent shaft. Reducing RPM can be accomplished by using two or more pulleys and belts to transmit and change the speed of rotation.