Finder relayIt is a very common electrical appliance in industry. We all know that finder relay is an automatic control appliance that acts according to a specific input signal. There are many kinds of finder relays, such as intermediate relay, thermal relay and time relay.
Km intermediate relay is usually used to transmit signals and control multiple circuits at the same time. It can also be used to directly control small capacity motors or other electrical actuators.
The structure and working principle of intermediate relay are basically the same as that of AC contactor. The main difference between intermediate relay and AC contactor is that the number of contacts is large, the capacity is small, and only small current can be allowed to pass. When selecting finder intermediate relay, the voltage level and the number of contacts are mainly considered.
Fr thermal relay has larger expansion coefficient of lower metal and smaller expansion coefficient of upper metal. When the current in the main circuit exceeds the allowable value and the bimetallic sheet is heated, the free end of the bimetallic sheet bends upward beyond the gusset plate, which disconnects the normally closed contact under the tension of the spring. The contact is connected to the control circuit of the motor. When the control circuit is disconnected, the coil of the contactor is powered off, thereby disconnecting the main circuit of the motor.
When the KT time relay is energized, the pneumatic time relay uses the damping effect of air to achieve the purpose of action delay. After the suction coil is energized, the armature is sucked down to maintain the distance between the armature and the piston rod. Under the action of the release spring, the piston rod moves downward. A rubber film is fixed on the surface of the umbrella piston. When the piston moves downward, there will be a space of thin air on the film. Due to the pressure of the air below, the piston cannot move downward quickly. As air enters through the air inlet, the piston gradually moves downward. When it moves to the last position, the lever makes the microswitch act. The time delay refers to the period from the time when the coil is energized by the electromagnet to the time when the microswitch acts. The delay time can be adjusted by adjusting the size of the air inlet with the adjusting screw. After the suction coil is powered off, it recovers under the action of the return spring. The air is quickly discharged through the air outlet. This time relay has two delay contacts: one is the normally closed contact with delayed opening, the other is the normally open contact with delayed closing, and there are two instantaneous contacts.