How the speed relay works
Speed relay operating speed of not less than 100-300r / min, reset speed 100r / min. 2 When the speed drops below 100r / min. The speed relay contacts are disconnected, the contactor is de-energized, the main contact of the contactor is disconnected and the power is turned off quickly, and the motor stops rotating without reversing. 3 Remember that the speed relay is a motor that follows the controlled motor The size of the speed of the control circuit connected to or disconnect the electrical appliances, it will cooperate with the contactor to the motor reverse brake
Speed relay: is the speed to reach a certain speed or below a certain speed, so that the relay contacts the action of the relay.
There are two kinds of speed relay, one is mechanical, directly to the machine shaft or motor shaft speed out to promote the contact of the clutch. It is the use of centrifugal force to contact the action. There is also an electronic speed relay that removes the level that reflects the shaft speed of the machine shaft or motor shaft to drive the clutch of the contacts, similar to the Hall sensor. Applications: 1. Speed relay control motor braking method is generally connected to the reverse brake, the circuit is simple, when the motor in the brake after the start of the rapid decline in speed, speed relay detection motor speed is zero control brake contactor coil off open. 2. For overspeed protection, that is, when the motor overshoot alarm, speed limit; 3. Detection of zero speed, that is to determine whether the motor has stopped.
Action principle: speed relay rotor shaft and the controlled motor shaft connected, and the stator set on the rotor. When the motor rotates, the speed relay rotor rotates, the stator short-circuit conductor will cut the magnetic field, resulting in induced electromotive force, resulting in current. This current generates torque with the rotating rotor magnetic field, and the stator starts to rotate. When the turn to a certain angle, mounted on the stator shaft pendulum to promote the reed action, so that normally closed contact breaking, normally open contact closed. When the motor speed is below a certain value, the torque generated by the stator is reduced and the contact is reset under the action of the spring. Commonly used speed relay with YJ1 type and JFZ0 type. Usually the speed of the relay action speed of 120r / min, reset speed of 100r / min.
