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Reed switch life and dry reed switch life test

- May 28, 2018 -

Reed switch life and dry reed (reed switch) life test


Reed switch life

The life of the reed switch may vary greatly depending on the switching environment. After years of development, many improvements have been made to the reed switch, which has played a key role in improving its reliability.


Reed switches, because they have sealing properties and are free of consumables, can switch idle or signal loads by billions of times, and in most cases have minimal changes in contact resistance. In fact, the contact resistance often drops by about 5 to 10 milliohms.


Different types of reed switches, vitreous body length from 7mm to 50mm, can switch nanovolts to 10,000 volts, current from flying to 5A, DC to 6GHz frequency. In general, Huayi provides reed switches for sensors or relays. Its contacts include mercury contacts, tungsten contacts, tantalum contacts, tantalum contacts, and so on. These different reed switches adapt to a certain application.


If you want to optimize the life of the reed switch, be sure to test your circuit in the actual load to achieve your desired life. Especially when switching inductors, capacitors, or inrush current loads.


 


Reed switch life test

Reed switch life testing is a destructive test that uses different combinations of voltage, current, and operating frequency for reed switches to ensure product reliability. The parameters tested during the life test are OAT, RAT, and operation and release time.


Measurement parameters


Test Current - Specific Rated Current of Reed Switch

Test Voltage - Reed Switch Specific Rated Current Rating Voltage

Operating time - Monitor working time to 1 millisecond, 2ms contact

Release time - Monitor 1 millisecond, 1 millisecond contact break

Operating frequency - 50% duty cycle, 1 to 25 Hz standard size reed switch and 25 to 125 Hz for miniature reed switch

Contact resistance - less than 5% test load

Coil Drive - Overload 25%


Failure criteria


Contact resistance test load exceeds 5% upon contact

Contact resistance is less than 500% of the test load when contacting the terminal

"make" or "break" failed during operation

Reed switch weld

 


Windows


The load current and voltage required to establish the test environment are such that the reed switch performs continuous "make" and "break" operations. When running, the reed switch with the rated current flowing is connected, and the contact is disconnected when the interruption operation occurs, and no current flows. The rated voltage of the open contact through the reed switch remains during this period.



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A "make" failure can be identified by monitoring the status of the reed switch, 2 milliseconds after the coil is energized, for 1 millisecond in a row. If the reed switch "breaks" or cannot be closed in the 1-millisecond watch window, it is considered a "make" failure.


Repeat the process, pass the life test, the expected number of operations until the reed switch malfunctions. During this period of contact resistance monitoring can always understand the actual situation of the reed switch under load.


For the specific parameter abbreviations, please refer to the description of the reed switch parameters.


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