What Is A Reed Relay?

Reed relays are simple, reliable devices that have many advantages over other switching technologies and can often be the best solution for many applications where switching is required.

The heart of the reed relay

At the heart of a reed relay is the reed switch. It is made up of two ferromagnetic blades that are hermetically sealed in a glass tube, or reed, in either an inert gas or a vacuum. The contact surfaces of the blades are plated in a suitable material, typically Ruthenium, Rhodium or sometimes Tungsten, with the glass tube seal holding them in place ensuring the contact surfaces are aligned and have an appropriate gap to give the required sensitivity.

A reed relay is made up of one or more reed switches controlled by the electromagnetic field from a coil. When a reed switch is fitted within a coil and a voltage is applied, the current flowing through the turns of wire will generate a magnetic field that will magnetically polarize the blades so they become attracted to each other, coming together and closing the switch path.

With the only movement within the reed switch being the small blade deflection, they are regarded as having no moving parts that can be affected by mechanical wear, unlike electromechanical relays. And as the reed switch contacts are sealed in the glass tube, they are protected from contamination from dust or debris, or oxidization of the contact surfaces, making them more suitable for very low signal levels when compared to electromechanical relays where the contacts are open to the air.

Compared to other switching technologies

When compared to other switching technologies, for example, solid state relays, reed relays have far higher insulation resistances across the open switch and between the switch to the coil, resulting in significantly lower leakage currents when compared to semiconductor switches. And the simplicity of a reed switch and coil means they do not have the vulnerabilities semiconductors can have from spurious or transient pulses that may cause irreparable damage.

With a wide range of instrumentation grade, high-quality reed switches available capable of switching micro Volts to kilo Volts and the highly customizable construction, solutions to a wide range of switching requirements can often easily be found.

Watch What A Reed Relay Is And How It's Manufactured

Have a question or need further help?

For more information, please contact our technical sales team at techsales@pickeringrelay.com who will be happy to work with you & design a specific one-of-a-kind customised reed relay.

Or if you are unsure of your Reed Relay requirements please contact us.

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