Life determing tests on 50 years old switchgear of 11kV and 3.3kV

[khanengr]

Hi dear all,

I am conforted with a situation, I am provided with following switch gear which is about 50 years old, now I have to start them. We refubrished the switchgears, but when we started two motors of 3.3kV, arc flash occured in both separate relevant switchgears of motors, I showed the switchgear to third party they said that the switchgear has completed its life, now replace with new. But for management, I need tests to be performed on my switchgear to persue management that the current switch gear assembly is finished and we should buy new one, because it costs a lot. The details of Switchgears are as follow:

1. 11kV switchgear consists of Oil Circuit Breakers (OCB) for RMU and main incoming and primary of transformers.
2. MCC of 3.3kV for motors of plant, comprising of isolators and two types of contactors (Vaccum Contactors and Air Break Contactors).

Now, kindly advise me and name me the tests that needs to be performed on Breakers, Isolators and Contactors, so that I can determine their health, and usefulness.

Thanks to all.

 

[davidbeach]

Please don't spam the site by asking the same question in multiple forums. Please Red Flag one of your posts for deletion.

 

[Zogzog]

Nonesense, nuclear plants use 50 year old gear, very few replace with new becuase the older gear when properly maintained is more robust and will last 50 more years. Seems to me the refirbishment was not up to par, when done right it should be as good or better than it was when new.

You can find all the recommended tests in the ANSI/NETA Maintenence testing standard. You should look to a qualified testing company, if you don't even know what the tests are I doubt you have the equipment to do them.

 

[oldfieldguy]

I concur with Zog. Properly maintained gear fifty or more years old is very common. The difficulty with the gear is that as age increases careful testing, inspection and maintenance becomes extremely critical.

A case in point is that some 1950-vintage medium voltage (5-15 kV) equipment in the US used insulation systems that contained components incorporating pourable asphalt as part of the insulation. Over the years of repeated thermal cycles, this stuff tends to crack, creating problems with coronal and ozone, and the surface can harbor a layer of contaminating dust. A competent maintenance effort addresses problems like these and dozens of others, and while a maintenance outage for new gear might be a couple of days, the outage for the equivalent old equipment might take a week or more, especially if problems are found.

Further aggravating the situation is the availability of repair parts. The used parts market may supply some but I've know of cases where parts had to be fabricated from scratch.

Zog's reference to a competent testing company is a good initial step to evaluating the equipment.



old field guy