Standard Professional Definition The conventional electromagnetic relay is an electric control switching device which uses the principle of electromagnetic induction to realize the automatic on-off of a circuit, and is mainly composed of an excitation coil, an iron core, an armature, a reset spring, a dynamic and static contact component and a base shell. When the coil is electrified with rated current, a magnetic field is generated, and the armature is attracted to drive the mechanical transmission mechanism, so that the contact is switched; and after the coil is powered off, the magnetic field disappears, the reset spring pulls the armature to reset, and the contact is restored to the original state, so that the small current is used for controlling the large current, and the weak current is used for controlling the strong current circuit. Disassembly of core features Power source: the coil is electrified to generate magnetic force, and the contact is driven by independent armature and spring mechanical transmission; Contact structure: the moving and static contacts are exposed in the air inside the shell without sealing protection; Control logic: a low-power coil loop and a quarantine control a high-power load loop to realize electrical quarantine; Applicable scenarios: AC and DC power load on and off, is the most common switching element for industrial control and household appliances. Plain and simple version (applicable to reports and notes) The conventional electromagnetic relay is a universal electromagnetic switch which drives a mechanical contact to open and close through the electromagnetic attraction of a coil, can use a small signal to control a large load current, is reset by a spring, has an unsealed contact, and can bear a large working current.