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What is the Difference Between Electrical and Mechanical Relay Life?

Hardware: Switches>>General-Purpose>>PXI-2570

In the specifications for our electromechanical relay switch modules, the Expected Relay Life is described in terms of Mechanical and Electrical. What is the difference between these two different specifications?

Relay life is specified as a minimum number of cycles (action of opening and closing the relay) before the contact resistance rises above 1 Ω.  The expected life is divided into two main categories: mechanical and electrical life.

Mechanical Relay Life
This is the number of operations which a relay can be expected to perform while maintaining mechanical integrity.  Mechanical life is normally tested with no load or voltage applied to the power contacts. 

Electrical Relay Life
The minimum number of cycles the relay will make, carry, and break the specified load without contact sticking or welding, and without exceeding the electrical specifications of the device. 

Note:  Some switch modules are capable of tracking relay usage (see KnowledgeBase 4932N7I: How Do I Track Relay Usage on NI Switch Products?).  Refer to the the NI Switches Help (Fundamentals»General Switching Considerations»Relay Operation»Relay Count) for more information.

Related Links:
Developer Zone Tutorial: Relays
Developer Zone Tutorial: Reed Relay Protection
KnowledgeBase 4932N7I: How Do I Track Relay Usage on NI Switch Products?



Report Date: 06/22/2004
Last Updated: 06/08/2009
Document ID: 3ALGM32G

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