This section provides overview, applications, and principles of reed relays. Also, please take a look at the list of 16 reed relay manufacturers and their company rankings.
A reed relay is a relay that is activated by passing an electric current through a drive coil.
Since the magnetic field generated by the coil mechanically makes contact, there is very little leakage of current when the relay is not operating, compared to semiconductor switches.
Since the input and output sides are independent of each other and have no polarity, they are effective in reducing errors during installation. They are also resistant to pressure, have high insulation properties, are dustproof, and are not easily affected by outside gases.
Reed relays are used in a wide variety of electrical equipment. Although semiconductor relays are the current mainstream of relays, they are used in many applications where semiconductor relays are not suitable for use.
The following are environments in which reed relays are suitable for use:
A reed relay consists of a reed switch and a coil. The reed switch consists of a glass tube sealed with an inert gas and containing two leads with a gap between them. The reeds in the reed switch are made of a magnetic material that is subject to the force of a magnet, and the part of the reed switch where the reeds come in contact with each other when driven is fitted with a high current-carrying metal.
When a reed relay is driven, the magnetic field generated when current flows through the coil causes the two relays in the reed switch to come into contact with each other, thereby conducting electricity and functioning as a relay.
When a reed relay is driven, a magnetic field is generated by the coil. This may affect surrounding electronic components, so care must be taken in the mounting position and conditions of use. In addition, care must be taken to ensure proper usage of the circuit in which the reed relay is used, such as including a spark-elimination circuit and installing protection circuits for temporary high currents and reverse currents.
Relays have both electrical and mechanical life.
Electrical life is the life of a reed switch in a resistive load test, in which the reed switch is opened and closed by applying a load of rated voltage to the coil.
Specifically, it's the life of the relay depending on the volume of the load, the variety of the load, the frequency of opening and closing, and temperature conditions.
Mechanical life is the life in a no-load test where no load is applied. Relays are mechanical parts, and opening and closing them causes fatigue and wear of the parts themselves. Relay life also differs depending on the environment in which the relay is used, such as temperature conditions and cases in which a load greater than the coil's rated voltage is applied.
The following precautions must be taken when using reed relays:
Since the lead portion of the relay coil is sealed in a glass tube, cleaning does not degrade the characteristics of it. However, when cleaning the product, be sure to use a dedicated cleaner.
Magnetic fields generated by relay coils have an effect on the external environment. Especially in the case of close mounting, relays may not operate properly due to magnetic interference between relays.
Therefore, relays that are not magnetically shielded should be mounted with a minimum distance of 15 mm between relays.
Furthermore, the use of relays in the presence of objects that generate strong magnetic fields, such as transformers or permanent magnets, should also be avoided, as they may cause malfunctions.
*Including some distributors, etc.
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