Commissioning and maintenance test for protection relays

[521AB]

For several years again we will have substations equipped with numerical, static and electromechanical relays, from different manufacturers.
Apart for the fact that people get crazy, what are your guidelines for such type of testing? Do you differentiate the methods and the time interval for the different relay technologies? Do you follow the guidelines from the vendors or the directives of your company?
Open discussion

 

[dpc]

Electro-mechanical relays need more frequent testing than equivalent digital relay. We typically recommend testing e-m relays every 2 to 3 years, and digital relays every 5 years. The main issue with the digital relay is making sure the output contacts are still functional and that the relay still trips the breaker or lockout relay. Otherwise the relay self-diagnostics should alert to any internal failure in the processor itself.

With e-m relays, the relay characteristics can change with time so timing test, cleaning, and possibly re-calibration may be necessary.

 

[wbd]

Being a utility our guidelines for EM relays are 18 months, the digital type are longer like 3-5 yrs. Frequency relays are alittle different, basically yearly.
If it is an industrial environment that can be different. I know some plant environments that are very dusty (talc, calcium carbonate plants) that EM relays should be tested every 6 months to a year.