A relay is an electrically operated switch that controls one circuit by opening or closing contacts in another circuit. It allows a low-power signal to control a high-power load safely. Every relay, whether mechanical or electronic, has five main parts, each with a specific role in its operation.
The first part is the Electromagnet (Coil). This is the heart of the relay. When electrical current flows through the coil, it generates a magnetic field. This magnetic force pulls a movable arm inside the relay, which changes the position of the contacts. The strength of this magnetic field depends on the voltage and current applied to the coil.
The second part is the Armature. It’s a movable iron or steel lever that reacts to the magnetic field created by the coil. When the relay is energized, the magnetic field pulls the armature toward the coil, causing the contacts to either open or close. When the power is removed, a spring returns the armature to its normal position.
The third part is the Spring. The spring ensures that the armature goes back to its original position once the coil is de-energized. It maintains proper tension and helps in restoring the relay contacts to their normal (rest) state, making the relay ready for the next operation.
The fourth part is the Contacts. These are the actual switching points in a relay that open or close the electrical circuit. Contacts can be normally open (NO), normally closed (NC), or a combination of both. When the relay operates, the contacts change their position, allowing or stopping the flow of current to the connected device. The quality of contacts determines how much current and voltage the relay can handle.
The fifth part is the Yoke or Frame. It holds all the components together and provides a magnetic path for the coil’s field. It also supports the armature and ensures proper alignment during operation.
In simple terms, the five parts of a relay are the electromagnet (coil), armature, spring, contacts, and yoke (frame). These parts work together to switch circuits safely and efficiently, making relays essential components in automation, control systems, and electrical protection circuits.