RELAYS
RELAY
Relays are switches designed to close and open circuits electronically as well as electromechanically. It controls the opening and closing of the electronic circuit contacts. When the relay contact (NO) is opened, the relay is not energized by the open contact. However, if the relay is closed (NC), it is not energized due to the closed contact. However, when energy (electricity or charge) is supplied, the states are prone to change.
Relays are either electromechanical relays or solid-state relays. For electromechanical relays (EMRs), the connections are activated or closed by magnetic power. There are no connections with solid-state relays (SSR) and switching is fully wireless. The choice to use electromechanical or solid-state relays relies on the electrical specifications, cost limitations and life expectancy of the device.
Owing to the design of the solid-state relays, there is residual electrical resistance and/or current leakage, whether the switches are open or closed. Tiny voltage drops that are produced are not normally a problem; however, the electromechanical relays have a cleaner ON or OFF state due to the wide gap between the contacts serving as a form of insulation.
Types of Relays
In addition to the electromechanical and electromagnetic relay, there is a wide variety of relays with different working principles, principles of operation and polarity.
Electrothermal Relay – When two different materials get in contact, a bimetallic strip is formed, and when it is energized, it bends. This bending allows the users to make contact connections.
Electromechanical Relay – When different mechanical parts are connected based on the electromagnet, contact connection is established.
Solid State Relay –This relay uses semiconductor devices to make a connection to ensure the effectiveness, efficiency, and easiness of the switching speed. This is commonly used for two reasons: faster-switching process and durability.
Hybrid Relay – It is the name given to the solid-state and electromechanical relays.
Advantages of Relays
- It allows you to control a remote device. It is not necessary to be near the device to make it work.
- Change contacts easily.
- Isolates the activating part of the actuating part.
- It works well at high temperatures.
- It is activated with low current; however, it can activate large machines of great power.
- With a single signal you can control several contacts at once.
- It can switch direct current or alternating current.
- Contacts are damaged over time and continuous use.
- They generate a lot of noise with the activation and deactivation of the contacts.
- Switching time is high.
Applications of Relays
Relays are not limited to transforming single inputs into single outputs at single points in the circuit. In other applications, a single relay can activate multiple circuits, allowing one input to initiate many other effects. Similarly, relays can be used in combination with one another to perform boolean logic functions that while possible to enact using other components, may be more cost-effective when implemented using relays. What is more, specific relays can perform more advanced functions than other electronic components. Time-delay relays, to name just one category, allow systems to run only for a set period or to start only after a set period. This introduces more sophisticated possibilities for constructing electronic systems.