Protection Relay Testing and Calibration

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Somewhere between one minute and one century. See your local code, or your power plant's own schedule. If they don't say, then try one year on for size.

So, ask the individuals at the power generation facility how long they spend doing it.

Sheesh...

If you mean the interval between test / calibration events, that depends on several factors. The interval can vary from 6 months or a year to as much as 5-6 years. THe older electromechanical relays (coils, rotating disks, springs, etc.) may need to be calibrated on an annual basis. If the environment is very dirty, it may have to happen even more frequently. Solid state ("numerical") relays usually only have to be tested and calibrated every 2-3 years. The state of the art digital, microprocessor-based relays can sometimes go as long as 5-6 years, depending on what your local codes or utility requirements dictate.

A good guideline for all sorts of high voltage apparatus maintenance and testing is the InterNational Electrical Testing Association's (NETA) Maintenance Test Specification (MTS). You can buy it through their web site:

http://www.netaworld.org/

Disclaimer: My employer is a member company in NETA. The organization is known worldwide as a leader in setting standards and quality assurance for high voltage electrical acceptance and maintenance testing.

It will vary from place to place.Your local authority on this matter is just a call away. Testing can be done when ever it is convenient or at least once during stipulated testing and calibration dates.

I have a lot of experience with both the old electro-mechanical and new electronic types not as one who did the testing, but as one who followed up failures. Back when only GE or Circle W made decent relays, quality was very high. The annual test was great. Now due to competition almost all relays have a lot more failures. Due to the larger systems failures do more damage. Currently, the problem is mostly premature failure. Most failures occur soon after first use. I would setup relay which usually involves an initial test, then I would retest just before energizing, then 6 months(finds any problems while warranties are good), then 18 months(from installation), but then the times can be lengthened. But never more than 5 years and I would be very uncomfortable with that. Electromechanical devices are more prone to contamination and the solid state computer types are more prone to power surge failures and heat damage. The failure rates are really nearly the same. It will probably get better with the solid state units over time, but right now as technology improves the products are cheapened by everyone so the end result is the same.

It was very common when going in after a terrible incident involving a failed relay to find 30 to 35 percent of the relays non-functional because they had not been tested since installation if then. It was really sad when bad relays caused loss of life in addition to monetary damage and loss of production. I have never seen a decent utility that didn't test annually. We had contracts for some really large facilities that included equipment replacement and we did annual on our nickel. Even then you could have a failed relay set there for nearly a year without knowing it, but relays do back each other up, and it takes multiple relay failures to cause big problems.

The company that sold you the equipment can also define the durations, types of tests as well as sequencing of the same.

So contact them, they are the best source.