FAQ02810 of General Purpose Relays FAQ

When switching a minimum load, contact resistance of the contact points may be considered a problem.

However, even if a high contact resistance happens to be generated, it may recover in the subsequent operation. Also, formation of contact films may increase the contact resistance.

Whether or not a contact resistance value is considered a problem should be judged by the type of problem occurred in the used circuit.

For this reason, a criterion for failure of Relay contact resistance is defined with an initial value. The minimum applicable load is one of the measures of failure and the failure rate is usually expressed as P-level (reference value).

In addition, some of Relay contacts are suitable for minimum load switching and some are not.