Relay generally refers to electromagnetic relay, that is, mechanical action. The essence of the relay's working principle is to use one circuit (generally small current) to control the on-off of the other circuit (generally large current), and during this control process, the two circuits are generally isolated.
The basic principle of the relay is to use the electromagnetic effect to control the mechanical contact to achieve the purpose of making and breaking. It energizes the coil with iron core - the coil current generates a magnetic field - the magnetic field absorbs the armature to act on and off the contact. The whole process is a process of "small current - magnetic - mechanical - large current".
What is the use of relay
Relay is an automatic switching element with isolation function. When the change of excitation quantity in the input circuit reaches the specified value, it is an automatic circuit control device that can make the controlled quantity in the output circuit change in a predetermined step.
The relay has an induction mechanism that can reflect some external excitation (electric or non electric), an actuator that can control the controlled circuit "on" and "off", and an intermediate comparison mechanism that can compare, judge and convert the magnitude of the excitation.
Relays are widely used in remote control, telemetry, communication, automatic control, mechatronics, aerospace technology and other fields to control, protect, regulate and transmit information.