Factory Acceptance Test of 15kV Switchgear

I recently attended the factory acceptance test for 13.8kV medium voltage switchgear at Powercon’s facility in Severn, MD.  The gear is made of two identical line-ups that are both made of three mains and two ties (6 service feeders total).  We rigorously tested every control circuit, every interlock, and inspected it from top and bottom and I’m happy to say it passed with flying colors.  It is amazing to think that in just a few weeks this gear will go from the factory floor to some building where it will replace gear that has been there for 50 or more years, to sit there for another 50 or more years.  The new gear includes the same controls as the old gear with the addition of modern microprocessor based relays and meters that will allow trending and live voltage, current and KVA values via an interface to the building management system.  I can only imagine what technology the next switchgear will include.  The breakers in the new gear are also 300lbs lighter each and about ¾ the height of the old breakers.

The factory test included opening and closing the 10-1200A breakers which utilize 125VDC control voltage more than a dozen times each and to tell you the truth, I don’t think I could ever get tired of hearing the sound of the breakers open, close and charge.  The bang of the breaker opening and closing and the sound of the charging spring motor are unmistakable and definitely unforgettable.  I also enjoyed the sound the 1200A, 15kV bus makes when being hi-potted at 36kV for a minute at a time.  The steady sizzling sound makes your mouth water like you’re waiting for a steak to cook.  The potential for the bus to fail, (and in the back of your mind your hope that it does), also adds to the excitement.  Luckily (or unluckily) the bus didn’t fail which would have caused a large bang, a lot of smoke and about a month delay for shipping. 

When the client can afford it, factory tests, or even commissioning the gear after it is installed is the way to go.  This is not just hi-potting the bus, but making sure each relay works, testing the breakers and the control circuits.  It ensures that everything is built to the design and eliminates embarrassing defects that are found while the gear is in use.  Also, as the engineer of record it is nice to see your designed equipment operate as you designed it!