Electromechanical Relay: Operation and Wiring (Illustrated Tutorial)
Note: This guide was fully revised in April 2026 to reflect the latest standards and technological developments.
A relay is an electromechanical device
A relay is an electromechanical device that acts as a switch. It can be used to control one or more electrical circuits. It is an electrically controlled switch. It consists of an electromagnet (moving wire coil) within a magnetic field. When the coil is energized, the relay contacts move to establish or break an electrical circuit.
Relays are used when it is necessary to control a circuit by a separate low-power signal, such as from a sensor. For example, a low-power signal from a photoelectric cell can be used to control:
– Electromechanical relays are DC relays that operate on the principle of closing a circuit through an internal mechanism.
– They are used for signal control, safety devices, motor control devices, generator control devices, and emergency power control devices..
In a monostable circuit, the output changes state when the input is applied and returns to its initial state when it is removed.
A bistable circuit has two stable states and can be switched between them by applying an external stimulus.
Bistable circuits are used in digital electronics to store a bit of information.
The two stable states are commonly referred to as “set” and “reset”.
Interactive Simulation (Velxio)
Schneider Electric LRD08 Thermal Overload Relay (2.5-4A)
🛠️ The essential tool for this project.
Test the relay behavior in real-time with our integrated simulator:
