Is there more than one method used to calculate relay reliability fallure rates ?

Yes. There are several methods used to calculate relay failure rates. The accepted method and three other methods that are sometimes used to enhance a particular failure rate are shown in this table.

 

ACCEPTED

Method : Terminate testing with a failure, and one operation is one coil energized and de-energized cycle.

Total Operations : 10 000 000

Failures : 6

Failure Rate* : 0,600

 

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SOMETIMES USED

Method : Terminate testing without a failure, and one operation is one coil energized and de-energized cycle.

Total Operations : 10 000 000

Failures : 5

Failure Rate* : 0,500

 

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Method : Terminate testing with a failure: one operation is a contact make/break per coil energized and de-energized cycle.

Total Operations : 80 000 000

Failures : 6

Failure Rate* : 0,075

 

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Method : Terminate testing with a failure: one operation is a contact make/break per coil energized and de-energized cycle.

Total Operations : 80 000 000

Failures : 5

Failure Rate* : 0,063

 

*Failure rate is expressed in % per 10 000 operations.