What is a relay: A relay is an electronic control device that has a control system (also called an input loop) and a controlled system (also called an output loop). It is usually used in automatic control circuits. It actually uses a smaller current A kind of "circuit breaker" to control a larger current, so it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.
A relay refers to a device that can produce a jump in one or more electrical output circuits when the input (or excitation) meets certain prescribed conditions.
The relationship between the input and output of the relay in the whole change process becomes the relay characteristic or control characteristic of the relay. Calculate the input loop volume, Y represents the output loop output
When the input quantity changes continuously to a certain quantity xa, the output quantity Y changes abruptly, increasing from 0 to the Ya value. At this time, when the input quantity continues to increase, the output remains unchanged. On the contrary, when the input volume decreases to xb, Y suddenly decreases from Ya to 0. xa is called the action value of the relay, xb is called the release value of the relay, and Ya is the load of the relay.
What are the types of relays?
(1) Overcurrent relay (referred to as overcurrent relay). When the current exceeds the set value, the relay will act or close the contact.
(2) Differential relay. It refers to the relay that determines the action according to the difference between the input and output of the protection device when designing or using the relay.
(3) Directional relay. A relay that operates according to the relative phase angle of current and other currents or reference voltages.
(4) Distance relay. This terminology means that the input of this type of relay is basically a function of the distance between the relay installation location and the point of failure. The distance relay can be used to reflect the phase angle difference between current, voltage, and current and voltage. Through these quantities, the impedance of the input relay, which is proportional to the distance from the fault location, can be calculated.
