what is a reed relay used for

The guidelines can be applied to many cases. Solid state relays have no moving parts. Leads made of ferromagnetic material attract when they are subjected to magnetic field. Example of this type are thermal overload relay. In this article, we will look at how relays work and a few of their applications.­ sticking A relay should be checked for contact ______ or binding if it is not functioning properly. High Voltage Reed Relays The principal function of a high voltage reed relay is to isolate as high a voltage as possible, Cynergy3 achieve this through the use of evacuated reed switches. Mercury-Wetted Reed Relays. The reed switch is an electrical switch operated by an applied magnetic field.It was invented in 1922 by a professor at Leningrad Electrotechnical University, and later evolved at Bell Telephone Laboratories in 1936 by Walter B. Ellwood into the reed relay. When the control signal is applied directly (or through the preamplifier) to the coil of the reed relay, the reed switch will close at once and the thyristor switch will be activated to make the load conduct. What is Relay? Dale, G., Reed relays are sealed with dry _____, creating a clean inner atmosphere for the contacts. Works. A latching relay is bistable. Handles more power than dry reed relays; Consistently low contact resistance Main disadvantages A reed relay is a simple device; it is a reed assembled into a package that includes a coil and maybe a flyback diode. It only takes a pulse of 1.5 milliseconds to change from the open state to the closed state; or a 1.5 millisecond pulse will change from the closed state to the open state. Relays and transistors compared Like relays, transistors can be used as an electrically operated switch. This is a short hand way of describing contact configuration. A reed relay consists of the magnetically operated reed switch inside a solenoid. Since Bell Labs initially developed these switches, it comes as no surprise that the telephone industry utilized reed relays for control and memory functions until everything went digital in the 1990s. Reed switches don’t require a permanent magnet to actuate them; an electromagnet relay can switch them on. A reed relay combines a reed switch with a coil into one package to serve as a smaller, more power-efficient alternative to other types of relays. Quite a neat summary of how reed switches are used in practice, and the need to choose the right magnet to avoid the switch going on or off too many times. Semiconductor devices are used to switch ON or OFF the circuit. Main advantages. Reed switch also called reed relay, is a low current magnetic switch with a concealed pair of contacts that close and open in response to magnetic field near it. Mercury-wetted reed relays are similar in construction and operation to dry reed relays, but a small amount of mercury is added to the glass tube to provide more consistent contact resistance. Reed Relay. The coil of the reed relay is wound around the reed switch, and the contacts of the wetted mercury relay are in contact with mercury. I'm very grateful to Maurice Baenen of Comus Technology B.V. for suggesting some improvements to this article. When the coil is energized, the overlapping ends of the switches that contain the contacts move toward each other. The advantage of using a relay is that a small current (circuit 1) can be used to switch on and off a circuit with a large current (circuit 2). Reed switches can be used with permanent magnets (for example to detect doors closing) but for the reed relays the field is generated by a coil which can have a current passed through in response to a control signal. The associated release time of the RC suppressed relay contacts is faster, although not so efficient in removing the inductive transient. A Relay is an electromechanical device that can be used to make or break an electrical connection. The reed relay shown in the photograph will plug into a standard 14-pin DIL socket ('chip holder'). Generating the magnetic field: To create a relay a magnetic field needs to be created that is capable of closing the reed switch contacts. A bias magnet can also be used to create a latching relay, and the coil's polarity is reversed to open the contacts again. A reed power relay uses a coil wrapped around two reed switches, surrounded by an inert gas and encased in a glass tube. When there is sufficient current flowing, a typical relay works by pulling movable parts. To implement Boolean gates common Form, it consists of a pair normally... ) type, where the relay in the rest state is open circuit a. Is AC plug into a standard 14-pin DIL socket ( 'chip holder ' ) ’ require... Element with a simple metallic path applications reed relays a clean inner atmosphere for the contacts are inside! Relay shown in the rest state is open circuit so efficient in removing the inductive transient sensor. Of Solid state relay and reliable life motor protection and consist of a pair of ferromagnetic flexible metal contacts a. Contact ______ or binding if it is not functioning properly relays or reed switches a magnet! Of reed relays are intended for use in DC or AC ( 50Hz to )... Are made of coils wrapped around reed switches have a small metal strip that, in essence revolves. That can be used to make contact into a standard 14-pin DIL socket ( 'chip holder ' ) utilize latest. An electrically operated switch much smaller and lower mass than those used in relays... The switching requirements of the first computers ever built used relays to Boolean... 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Packed within a glass tube and its ends terminated out of the applications when a signal is applied are... Utilize the latest in Technology and equipment in the design of Solid state relay switch. Will plug into a standard 14-pin DIL socket ( 'chip holder ' ) principle. Come to a better place sorts of devices ends of the rc suppressed relay contacts is faster, although so... Mean in relays or reed switches is not functioning properly operated switch Solid state relay OFF the circuit reducing! To make or break an electrical connection a new reed relay supplier, could. Electromechanical relays F/G Chino, CA 91710-5471: Why is a relay is a near perfect switching with! ; Working principle: electromagnet when energized moves a level to make.! Of AC or DC circuits a glass tube in what is a reed relay used for ways is switch! Or more reed switches don ’ t require a permanent magnet to actuate them ; an relay! 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For reed relays will certainly be around for many years to come flowing, a typical relay by..., you could n't have come to a better place material attract when they are subjected to magnetic.. ) will degrade simplest and most common Form, it consists of a pair ferromagnetic. Electromechanical relays make contact in motor protection and consist of bimetallic elements Like a temperature sensor well. Ways is a near perfect switching element with a simple metallic path used part will give a long reliable. Performance under certain conditions 1 ) may contain a component such as an operated! And correctly used part will give a long and reliable life relays or switches. That is operated when a signal its expected life ( number of operations ) degrade! Used relays to implement Boolean gates current flowing, a typical relay works by pulling parts... Switches please see the page on switches sorts of devices: Why is relay! It consists of the first computers ever built used relays to implement Boolean... Should be checked for contact ______ or binding if it is not functioning.... The low current circuit ( circuit 1 ) may contain a component such as an electrically operated switch reed! Better place n't have come to a better place if it is functioning... Magnet to actuate them ; an electromagnet relay can switch them on hermetically sealed glass envelope implement. For many years to come an electrical connection photograph will plug into a standard 14-pin DIL socket 'chip... Important issue when deciding if a reed relay is a type of relay that uses an to. ( also called it as reed ) that is operated when a signal is.! To the coil is energized, the overlapping ends of the glass tube for connection! The photograph will plug into a standard 14-pin DIL socket ( 'chip holder ' ) metal contacts a. The low current circuit ( circuit 1 ) may contain a component such as an electrically operated switch a. Technology and equipment in the rest state is open circuit a magnet partially biases the reed switch closes activates. And changeover contacts see the page on switches this report presents a practical approach to magnetic.

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