A latching relay is an electromagnetic switch that stays in either the “open” or “closed” position until it is moved to the opposite position by an external trigger. Unlike a regular relay, which has a spring-loaded mechanism that returns the switch to its original position when power is removed, a latching relay stays in the position it was last moved to. In this article, we’ll take a closer look at how latching relays work and some of the benefits of using them.
How Latching Relays Work
Latching relays are used in a variety of applications where it is necessary to keep the circuit in a particular state, even when power is removed from the relay.
The way they work is relatively simple – when an electric current flows through the coil of an electromagnet, it creates a magnetic field that either opens or closes the switch, depending on the orientation of the coil. When power is removed from the coil, the internal mechanism of the relay keeps the switch in its current position so that the circuit remains open or closed.
There are two types of latching relays – those with an “open” frame and those with a “sealed” frame. Open-frame relays have their coils and contact points exposed, while sealed-frame relays have them enclosed in a housing. Both types are available in either PCB or solder lug mountings.
Benefits of Using Latching Relays
Latching relays offer several advantages over regular mechanical switches or standard electromagnetic relays.
First, because they don’t require constant power to stay in their current state, they are more energy-efficient than standard electromechanical switches.
Second, they can be used in applications where it is not possible to physically move the switch to its opposite position (e.g., using a push button or lever).
Third, because they don’t have any moving parts, they are less likely to fail due to wear and tear. Finally, latching relays occupy less space than standard electromechanical switches, making them ideal for use in compact electronic devices.
Applications for Latching Relays
Latching relays find applications in a wide range of electronic devices, including security systems, industrial controllers, vending machines, and automotive electronics. They are also used in many consumer products such as toys, cameras, and synthesizers.
For example, latching relays are often used in security systems to control doors and windows. When the system is armed, the relay is activated and the doors and windows are locked. If someone tries to break into the building, the alarm will sound and the doors and windows will remain locked until the security system is disarmed.
In industrial controllers, latching relays are used to control process loops (e.g., controlling temperature or pressure). When power is removed from the controller, the state of the process loop remains unchanged thanks to the latch feature of the relay. This prevents process upset when power is lost or restarted after maintenance on the equipment.
As any engineer knows, switches are an essential part of any electrical system. They are used to control the flow of current and can be either mechanical or electronic. While most switches are momentary, meaning they only close the circuit for a brief period of time, some applications require a switch that can maintain its position. This is where a latching relay comes in. Latching relays have two stable states, “on” and “off,” and can be activated with a brief pulse of electricity. This makes them ideal for use in applications where it is necessary to maintain the current flow for an extended period of time. While latching relays are not suitable for all applications, in specific scenarios they can provide a crucial advantage.
Conclusion:
Latching relays are electromagnetic switches that stay in their current state (either “open” or “closed”) until they are moved to their opposite state by an external trigger (unlike regular mechanical switches which return to their original state when power is removed). Latching relays offer several advantages over regular mechanical switches or standard relays such as being more energy efficient and having a smaller physical footprint. Latching relays find applications across many industries including security systems, industrial controllers, vending machines, and automotive electronics.