Why Do Magnetic Reed Switches Fail?

Magnetic reed switch is a kind of switch made based on the principle of electromagnetic induction. It was originally used in conjunction with stepping/transfer and electronic instruments and testers. With a sealed enclosure, it has excellent quality and reliability and can exist or be applied in most environments.

Magnetic reed switches have a simpler structure, smaller size, higher speed, and longer service life than general mechanical switches; compared with electronic switches, they also have the characteristic of strong anti-load impact ability and high reliability. They are widely used in mobile phones, program-controlled switches, copiers, washing machines, refrigerators, cameras, disinfection cabinets, door magnets, electromagnetic relays, electronic scales, liquid level gauges, remotely transmitted gas meters, IC card gas meters, and electronic gas meters. As long as automatic switches are used in electronic circuits, magnetic reed switches can be used.

Common reasons for damage to magnetic reed switches

• The reason why the switch does not work is generally due to incorrect wiring or no power supply.

• The reason why the switch indicator light does not turn on is generally due to the incorrect use of alternating current and direct current of the power supply.
  

• The reason why the switch cannot be disconnected after being actuated is generally because the current and load exceed the rated parameters of the induction switch.
  

• The reason why the switch indicator light turns on and then off may be due to excessive load.
  

Reasons for the failure of magnetic reed switches

Magnetic reed switches are small devices used to detect the proximity of a magnetic field. When opened, they consume zero current and can cycle for at least hundreds of thousands or even millions of times. Magnetic reed switches are very suitable for low current applications, in which the circuit only checks the closing of the magnetic reed switch contacts to display the detection status. However, magnetic reed switches can also directly drive a certain load current. Some magnetic reed switches can be used in situations where the load current is greater than one ampere.

However, some of our customers believe that as long as the load does not exceed the maximum switch current of the magnetic reed switch, they can directly connect the switch to any load. Generally, this is not a problem, but it should be pointed out that this wiring method is not suitable for inductive loads, such as small motors or relays. Although magnetic reed switches can directly drive some of these loads, some methods must be used to limit the voltage spike generated when the inductive load magnetic field is eliminated when the circuit is disconnected.

Inductive loads (such as electric motors or relay coils) store energy when current flows through them. If the current is interrupted, the energy must be dissipated in some way. When the magnetic reed switch is disconnected in this state, a large voltage spike will be generated on the coil, which will then form an arc at the magnetic reed switch contacts. This will significantly reduce the service life of the switch and even weld the contacts together in extreme cases.

For DC applications, a diode can be connected in parallel with the load to minimize the arc. This design allows the current passing through the diode to cycle back to the coil, thereby dissipating energy through the coil.