A Single Channel Relay Module
The relay is a switch which operated electrically and mechanically. The relay made up of Electromagnet and a set of contacts. Electro Magnet used for switching. Relay Module available in 5 V, 12 V.
Types of Relay:
- Electromechanical Relay-Power relay.
- Solid State Relay-Switching mechanism by magnetic force.
It has 5 terminals – Vcc, GND, NO, NC, COMMON.
- Vcc – From MCU – 5 V/9 V/12 V.
- GND – From MCU.
- NO – To output device – Normally opened.
- NC – To output device – Normally closed.
- Common – To output device (GND).
It has a movable switch key and the coil is the heart of this component. Movable switch moves over NO and NC terminals with one end fixed at COMMON. An Electromagnetic Coil kept nearer to the movable switch. It kept in such a way that when coil excited it pulls key and rests in NO terminal and else excited it rests on NC terminal.
A Relay contains sensing unit, an electric coil which powered by AC or DC current. When the current or voltage applied exceeds the threshold value, the armature activated by a coil, in turn, make the contact closed or open. When power supplied, a Magnetic force developed which actuates the switching mechanism in a relay.
Normally Open Contact:
This Switch normally open. Whenever there is a power supply or an external source, this act as a Closed Circuit. In the Relay, this excited when the electromagnet produces Magnetic Field. The magnetic field attracts the movable armature and rests on NO contact. This is the important part of the relay. In this, the load connected. Therefore, this act as a control part.
Normally Closed Contact:
The Switch normally closed. Whenever there is a power supply or an external source, this act as an Open Circuit. In the Relay, this opened when the electromagnet produces Magnetic Field. Initially, the armature has attached with NO contact.
When the coil excited, the coil act as an Electro Magnet. This produces Magnetic Field attracts the armature or Movable coil. They lay on NO open contact. The movable arm is NC contact, again contact NO. The loads connected to NO contact. If the relay is de-energized when it is in contact with NC means, it becomes as an Open Circuit. The movable arm returns back to NC when the supply stopped with the help of Spring.
- Telephonic exchange.
- Logic operation.
- ON/OFF control.
- Motor speed control.
- High power load control.
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