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Posts Tagged ‘switchgear’

Important Circuit Breaker Maintenance Tool – Wasp Spray

March 21st, 2011 1 comment

On a field service project, the customer was amazed at how much equipment we had on the large service vans. Besides the test equipment for old and newer circuit breakers and for oil filled power transformers and switchgear, we had the equipment and tools to maintain the switchgear and make many potential repairs. Plus generators, fuel and lights and much more. The customer asked, kind of as a joke, if we had anything on the trucks that was very important but wasn’t technical. This was a shutdown project where the power was turned off at 5:00 AM and had to be back on by 11:00 AM. A lot of work in six hours, including replacing one of the circuit breakers.

 

The immediate simultaneous response from two Engineering Technicians was, “Hornet Spray.”  Each truck has at least one can of hornet, actually wasp spray, in a can that will spray a stream 10 to 15 feet. We learned decades ago that it can be painful if you have a short shutdown project and open up the switchgear to access your favorite Square D circuit breakers or Westinghouse circuit breakers or new Siemens circuit breakers and you find the switchgear to be a hotel for a bunch of wasp nests. Hard to find a volunteer to take the bite clearing out wasp nests so you can replace circuit breakers. Instead, a little stream of spray here and there and you’re ready to go. No customer wants their project put at risk because of a few bees, even if they are mad. The bees that is. It’s a magic solution for a non technical problem.  So that’s something non technical but extremely important for an outdoor project to inspect, test and maintain circuit breakers and electrical switchgear. Don’t leave home without it.  

Circuit Breakers in Switchboard Buried in Sand

December 6th, 2010 Comments off

Sometimes MIDWEST runs into switchgear and circuit breakers in such harsh environments that you would wonder how they don’t blow up, much less work properly.  An example is some switchgear and old circuit breakers found in foundry environments. The condition of electrical equipment in foundries is 100 times better than 25 years ago. But there is still one thing that has not changed for some foundries and that is sand in electrical switchgear. Some foundries still have their main panel boards and some switchgear in open foundry areas, rather than in clean positive pressure rooms.

 

We recently were called in to repair a 2000 amp circuit breaker used in an open foundry environment. It turned out the old circuit breaker was not a breaker at all, but rather was a 2000 amp bolted pressure switch. The electrical switchboard had over 6 inches of sand in the bottom and 3 or 4 inches on top. The main horizontal bus feeding the risers for the circuit breakers, was partially buried in foundry sand. The service technicians said they actually scooped the sand out before even trying to use vacuum equipment. Fortunately the sand didn’t carry anything with it that acted as a conductor. This isn’t always true. In this case, the sand was just more insulation.

 

Maintaining the bolt lock switch and the circuit breakers was a nasty job. The covers had to be removed from every breaker to clean the operating mechanism and to get the sand out of the contact and arc chute area. And all our efforts were only temporary since the environment was unchanged. More serious was the fact that foundry dust would be inside the over current trip devices of the circuit breakers. Therefore the operation of the trip devices was unreliable, even unsafe. It wouldn’t make any difference whether these old circuit breakers were Square D, Westinghouse, GE General Electric or Cutler Hammer. Foundry dust and sand doesn’t care who the manufacture is. Even a brand new circuit breaker would be a victim to the sand.

The illusion was the circuit breakers were okay because they didn’t trip. It was only when the owner tried and failed to operate the main switch did they realize that maybe the panel board and breakers needed some attention. This was not the first, nor will it be the last, switchgear, panel board, or circuit breakers that we find basically buried in sand.

Air Breaker – Real Life Stories

May 14th, 2010 Comments off
 
DS420 Westinghouse Low Voltage Circuit Breaker

DS420 Westinghouse Low Voltage Circuit Breaker For Sale

To enclose or not to enclose? That is the question. Shakespeare phrased it exactly right, (to be or not to be) but the bard was not referring to switchgear of course. Enclose, according to Webster’s, means “to close in”. An “enclosure” in switchgear idiom is a type of electrical device surrounded “closed in” with sheet metal which serves to protect the device from environmental factors and to protect people and other creatures of the night from exposure to hot conductors.

 

 But what about enclosing the enclosure?

 

A large manufacturer we have worked with over many years, has a secondary breaker lineup located in a mezzanine section of their plant. Some amount of oil and dirt from the manufacturing process gets out into the plant atmosphere. These particles get scattered to the 4 winds of the plant settling in particular concentrations in various regions of the plant. The plant’s mezzanine section was one such region. For many years the switchgear located in the mezzanine remained open and exposed to contaminants in the air of the plant. Additional time and expense were required at annual shutdowns to clean and maintain the switchgear properly. The LVACB’s (low voltage air circuit breakers) in the lineup were literally covered with a film of oil from the environment. This oil and dirt accumulates in insulation components and raises the specter of bad things happening. Even the best maintenance program in the world cannot make up for certain burdens placed on equipment. Then someone in the plant got smart. A room was built around the switchgear completely closing it off from the plant atmosphere. One needn’t convince plant maintenance people of the value of these types of prudent cost saving measures. They see it first hand. The people upstairs who control plant funds often present a greater challenge.