knowshorts

I was hanging out with a facility manager yesterday and we we got to talking. His facility is heavily dependent on cooling. He has redundant 1200 amp 480 volt sections each feeding a pair of air handlers and a chiller and necessary pumps. His chiller yard is PMed every month by an HVAC contractor, but we got to talking, what about the electrical?

Feeders can be meggered and recorded and connections can be torqued. But what about the gear and breakers? What is the best thing to do here? At first we were thinking about having spare breakers, but how reliable is that? I've seen off the shelf breakers not work. What about having spare breakers and then getting them a 3rd party inspection? I was thinking shutting down one section and having all the breakers tested at once, on site. That way the gear and all the buss can be inspected also. If we go that route, how long does that typically take? And how often should this testing be performed?

Gear is GE with SGLA type frames with SRPG rating plugs.

If they lose this gear, it can be detrimental, so I think it might be an easy sell.

Zog

MCCB's are pretty much maintenence free, not much you do to them. Testing wise you would do insulation resistance, contact resistance, and trip testing. Also test any accessories that go with those breakers. ANSI/NETA has a full list of inspection and testing recommendations for MCCB's. The testing intervals would be based on envoronment and criticallity but in general every 3 years or so. Annual IR testing would also be a good preventitive test.

Any spare breakers purchased should be fully tested and come with a test report, if not get a 3rd party to do so. With MCCB's spares are usually your best bet because if one fails in place or during testing there is not much you can do to repair them.

That is how it is usually done, the time depends on the amount of equipment they have plus set up time for your equipment. If you do primary injection testing as ANSI/NETA requires you will need to remove each breaker to test and retorque when done. Plan on investing at least $20k for a test set if you do not have one.

MDShunk

For situations like that, I always recommend they get a double end fed switchgear lineup, and/or get spares of the critical branch breakers. A project I did a couple years ago was a chinese food cold storage warehouse, and I installed essentially an entire spare service. Extra air switch on the pole, extra padmount transformer, and double end fed the gear with a main tie main in the middle. Cheap insurance, considering what their losses could be. They have a shelf program with the supply house I got the equipment from, and the supply house keeps the critical breakers in stock at the customer's site, but they will pull them if they need them quickly for another customer.

When I have a customer with a critical breaker or switch that has failed at o'dark-thirty, that would otherwise be rebuildable, I talk them into installing a certified used or new breaker, and have their old breaker or switch rebuilt as an available spare. More people than you would think bite on that idea pretty quick.

__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.

Zog

I get that call every day, we call them the "once bitten, twice shy" calls. I hear this from maintenence or operations managers all the time "I don't want thsi to ever happen to me again, I could lose my job".

MDShunk

As an aside, I'm pretty sure a few people I've had contact with have lost their jobs as a result of one of these downtime instances. A shame, really. Some people think the maintenance boss' have a crystal ball. Those same people are the ones that balk at the price of electrical PM contracts.

__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.

Zog

Or the same people that went with the cheapest initial install design. Draw out gear? Bah! Spares? Bah! Redundant system? Double bah!

dthurmond

In our facility we test all 4160 and 575 vot switchgears every three years. Makes for a very difficult start up the following Monday.

MDShunk

Ain't that the truth. Manufacturing equipment runs perfectly fine until you turn it off and try to turn it back on again. Magical things happen to machinery during shutdown weekends.

__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.

mcclary's electrical

I worked in an industrial environment for 15 years and it is absloutlely amazing how many things run perfectly fine up until you turn them off, and then they won't start back.