Every day MIDWEST’s Switchgear Division receives interesting calls, mostly about technical stuff. Often just plain old problem solving. And sometimes an emergency request for a replacement bus plug. Every once in a while we are asked whether the bus plug we sold was new or used. They couldn’t tell the difference. An example is a call about a Square D PQ3603G bus plug. The customer thought we made a mistake and sent them a new bus plug instead of a used PQ3603G. He was a bit surprised when we told him it was used, but had been reconditioned by MIDWEST. The reconditioning process is a full detailed disassembly, reconditioning of components, reassembly and final quality control testing and inspection. Thirty years ago, the common practice for some companies may have been to just wipe a used bus plug off and send it out the door. Those days should be long gone. Unfortunately there are suppliers that still don’t do much more than cosmetics. MIDWEST has a huge advantage.We are a full service electrical testing and switchgear maintenance company and have been for over 30 year. In addition to high current and high voltage test equipment, we have test stations to simulate normal installation and operation of electrical equipment. Reconditioning a used Square D PQ3603G bus plug to look like new is routine work at MIDWEST.But it is always nice to get a compliment from our customers.We passed it on to the Switchgear Services Shop.We have received similar compliments about other equipment, such as fused panel board switches, circuit breakers, transformers, etc.
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During a routine Infrared Scan of a large manufacturing facility, our Thermographer found an interesting, but not uncommon, problem. A 400 amp Square D bus plug, PBQ3640G, was lit up like a dim light bulb. That means the entire bus plug looked warm, not just one area of the bus plug. Note, when viewed with infrared, it does not take much of a temperature difference for an object to look dramatically warmer than the area around it. But this was hot enough to indicate there was a problem, an overheating problem that was not localized inside the bus plug. While trying to angle for another view of the bus plug, our Thermographer discovered three different feeder conduits coming out of the 400 amp bus plug. One went to a 400 amp panel board, one went to a 225 amp lighting panel, and one went to a molding machine.As it turned out, there was a lot of load diversity, but the electric heaters on the molding machine were just too much. There was not a problem yet. There were no poor connections causing the heat. But the total load on the 400 amp bus plug was high enough to make the entire bus plug look warm under Infrared. If they continued to add load to the panel board or to the lighting panel, the fuses in the bus plug would have blown. Ignoring the fact not all the individual feeders out of the bus plug were protected, sooner or later they were going to have a problem with the PBQ3640G bus plug. Their solution was to put the molding machine on a new separate bus plug.
During an Infrared Scan, or Thermographic Scan, of the electrical distribution system of a new account, MIDWEST’s Thermographer noted in his report a strange bus plug set up. A 200 amp Cutler Hammer bus plug had a 2 inch pipe installed right in front of the cover. The pipe was 3 inches from the bus plug cover and right near the operating mechanism. The pipe was just kind of hanging there. It didn’t have much support. It went to a huge molding machine near the Square D bus duct. So you couldn’t switch this 200 amp Square D bus plug from the floor and you couldn’t open the cover of the bus plug, if you had to, because of the pipe.Who in their right mind would do this?As it turns out, they had an emergency and had to get a temporary line to the molding machine as fast as possible. Apparently the line carried plastic used in the molding machine and this machine was their main money maker. So they just installed pipe temporarily as quickly as possible. And six years later, the temporary pipe was still there. It more or less had become permanent.Temporary installations evolving into permanent, is not an unusual occurrence. In the real world, production rules.And like it or not, the same rules that caused a temporary pipe installation, also prevent the permanent installation. In the electrical equipment world, this is somewhat self correcting when the equipment gets unhappy with a bang.Bus plugs do fail if they are ignored too long.Whether a GE General Electric, Square D or Cutler Hammer bus plug, it will eventually fail if ignored long enough. When these things happen, those temporary fixes come back to bite you.
Sometimes the biggest challenge MIDWEST runs into, when reconditioning old bus plugs and obsolete bus plugs, is rust. Ironically this biggest challenge usually has the easiest solution, scrap out the bus plug. Sometimes healthy parts can be harvested from the rusted bus plugs, but care has to be taken to assure the recovered parts have not also been damaged by rust. The problem with rust is that it can be very insidious. Let’s say we want to recondition a Square D bus plug, Siemens Bus Plug or Cutler Hammer bus plug. It doesn’t make any difference. The rust doesn’t care. The problem is, we frequently don’t know the extent of the rusting until we have disassembled the bus plug and started the metal refinishing. The surface preparation may reveal severe structural rusting that was not fully apparent cosmetically. Now we’re not talking about full blown metal failure where you could push your finger through the metal. That’s obvious. We are referring to non cosmetic deterioration that prevents professional surface reconditioning. And this is not always visually apparent. It might not even be discovered if a company just repaints on old ITE or Westinghouse bus plug, for example. MIDWEST is very carful of equipment from facilities that have been out of service and unheated for any period of time. Extensive moisture damage can occur and not be visible until MIDWEST begins the full reconditioning process. This is another reason we recondition and test our equipment. There can be hidden defects. Some structural, some functional, some electrical, and any of them could turn a bus plug into a piece of scrap metal.
It would be more accurate to say the Square D bus plug became a mouse hotel, but Rat Hotel sounds more dramatic. MIDWEST field services runs into some pretty bizarre circumstances. Some funny, some tragic, and some a little of both. In this case MIDWEST was called to replace a Cutler Hammer 400 amp bus plug that had smoked, code for faulted with some arcing and smoking action. The location was a storage warehouse, damp, with minimum heat. It was easy to spot the damaged bus plug because it was partially discolored, or maybe the dust all over it was just toasted. When MIDWEST opened the bus plug to see how much damage there was and to get the exact catalog number, they discovered the remains of a mouse hotel, or colony, or habitat. A smelly little mess. Apparently mice got into the bus plug through an unplugged knockout on the top side of the old bus plug. It wouldn’t make any difference if this was a 400 amp Squared D bus plug or 400 GE General Electric Bus plug, the problem was caused by the missing knockout closure. A few cents cost a couple thousand dollars before the job was all done. The mice got in through the knockout opening, built nests, and seemed to be doing okay until one of them “crossed the phases,” so to speak. There was one toasted mouse, plus other fatalities, and burnt up debris in the bus plug. The guys removed the bus plug, installed a replacement from MIDWEST’s Switchgear Services, and then brought the damaged bus plug back to the shop. The only remaining problem was finding a volunteer to cleanup and check out the damaged bus plug to see if it was worth full reconditioning. It wasn’t. Rats
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On MIDWEST’s list of “Ten things we will not do with bus plugs” is “We will not sell a bus plug that we have tested only.” In other words, we are not going to take a Square D bus plug and just test it and say it is okay. We are not going to take a Cutler Hammer bus plug and sell it without reconditioning it.We are not going to sell a GE General Electric bus plug unless we have reconditioned it and tested it first. We are not going to sell an ITE bus plug after doing only a “smoke test,” as one really old time electrical contractor was fond of asking us. An old timer’s really scary minimum specification. When he turned it on, he just didn’t want to see any smoke. That was all he was concerned with. So he said. Actually we worked with him for decades and he always came back because he knew we did everything, including reconditioning and testing the bus plugs, anyway. We are not going to sell a Siemens bus plug as is, even for temporary use. We are not going to sell a Westinghouse bus plug after reconditioning and testing, if it still does not pass our final quality control inspection. All these statements are a repeat of the basic same “We Will Not Test Only” from the list of ten things we will not do with bus plugs. Sometimes it can be enlightening to say one thing six different ways, if it is making an important point. For quality and safety, pleonasm may be your friend.
MIDWEST was asked how we can tell if a bus plug has been water damaged. What if a brand new bus plug is exposed to water, say rain. How can we tell after it has already dried off? If it’s new, how would MIDWEST even know it was exposed to rain or water? The answer goes to the heart of why MIDWEST fully reconditions bus plugs. If a bus plug has been exposed to water, we would know as soon as we disassemble it for reconditioning. The old or new bus plug hardware, nuts and bolts and washers, would have some rust. The exposed surfaces of bolt holes would have rust at the edges. This is more obvious than you might think. In addition, between the inside of the new bus plug enclosure and attached interior parts, we find dust that has the visual pattern of water exposure. Like spilling water on a surface that had just a little dust on it. After the water evaporates, you can still see the pattern of the water exposure on the surface. Usually all this is pretty obvious to the engineering technician doing the work, if they are actually reconditioning the replacement bus plugs. But, if a company is just giving it a shoe shine, meaning a little inside cleaning with a little outside painting, they may never detect the water damage. Even an insulation resistance test pole to pole and pole to ground may not reveal the damage. But it is there and it shortens the reliable life expectancy of the bus plug. Rust especially is insidious when it starts at support hardware. MIDWEST’s best suggestion is to buy fully reconditioned equipment if you are buying obsolete bus plugs, used bus plugs, or new surplus bus plugs. This is true whether buying Square D bus plugs, Siemens bus plugs, ITE bus plugs or any other manufacturer’s product.
About the craziest bus plugMIDWEST’s field services have seen was a circuit breaker style bus plug that had the circuit breaker removed and replaced with wire jumpers. Apparently this was done as an extreme emergency temporary fix. It was a 200 amp bus plug. To do this, the entire bus duct must have been turned off, otherwise the jumpers would have had to be installed hot, which would be crazy.The circuit breaker had been removed and insulated building wire used to connect the line side copper bars, of the 200 amp bus plug, to the feeder cables. The jumpers were connected to the feeder cables using taped up split bolts. The feeder went to the main fused switch for a very large molding machine, so there was fault protection at the machine. But the line side of the main switch could have had an extremely high arc flash hazard level, since the only protection was the main breaker for the entire 1200 amp bus duct. It could have been a Square D bus plug or a Cutler Hammer bus plug. Actually it wasn’t either, but the manufacturer of the bus plug doesn’t make any difference. MIDWEST’s Field Services runs into some of these nightmares now and then. The danger of temporary fixes is they often are forgotten and take on a permanent life within the power system. For temporary repairs, we suggest attaching yellow warning banner ribbon, or other safety measures, until the permanent repairs can be made. In this case though, the temporary fix was too dangerous and should not have been done.
MIDWEST was asked by a retired electrician why we bother disassembling a bus plug to recondition it. He worked for a contractor for years and they serviced bus plugs and bus duct a few times. But all they had to do was clean them off and operate them a couple
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times. They never found any problems. They didn’t bother removing them from the bus duct. He said he worked on GE General Electric bus plugs, Square D bus plugs and westinghouse bus plugs. He wanted to know what we would find that they didn’t. The obvious area of concern would be the disconnect fingers on the back of the bus plugs. These are not visible unless you remove the bus plug from the bus duct. It’s not unusual for disconnect fingers to be misaligned, bent or damaged by overheating due to improper fit on to the bus duct. In addition, we often find fuse holder supports or operating mechanism supports actually broken. A broken support for an operating mechanism is a disaster waiting to happen. It’s especially dangerous because it will fail right when you are operating the bus plug. And that’s a bad place to be if you are the one switching the bus plug. The concern is for the safety of the person doing the switching. It’s easy to repair or replace equipment. But it’s not so easy to repair or replace people or body parts.
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Whether it’s an ITE RV366 bus plug or RV364 or Square D PBQ4640 bus plug, any bus plug can have these defects. Many defects are more related to the installation and environment than to the particular manufacturer. The big deal is we know all the things that can go wrong with electrical bus plugs and most of these failures can not be found with a quick visual inspection of an installed bus plug by someone inexperienced, who has never tore one apart, or repaired one after it has broken or failed mechanically or electrically.
We asked MIDWEST’s Switchgear Shop for an example of a replacement bus plug problem or defect that would not be picked up by standardized reconditioning and testing procedures.Procedures that might be found in published data. We were looking for something that went directly to the value of experience. The value of quality workmanship.Here’s a quick example from one of MIDWEST’s switchgear Engineering Technicians.
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He spoke of a Federal Pacific bus plug, catalog number LSP 1436SN, 600 volt, 400 amp, just as an example. He said it could just as well be a Cutler Hammer Bus Plug catalog number HD 1364N, or a replacement Square D bus plug or Westinghouse bus plug. It didn’t make a difference.A service company could simply test, or repair or completely recondition a bus plug. Then perform the tests that look for current or voltage related problems. Do the quality control physical and mechanical inspection. The reconditioned Square D bus plug could look and perform so well that you might think it was brand new. But as part of the quality control, veteran Engineering Technicians
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know to double check the nameplate of the reconditioned bus plug with what they actually have. They said this could very easily be missed, because the nameplate is always correct, almost. The last error he found was a bus plug that had a neutral indicated in the catalog number on the nameplate, like the two just mentioned, but actually did not have the neutral bus. It had been removed. It came into the Switchgear Shop that way, as was determined by inspecting other bus plugs in the same lot. Just a detail, a really big detail. So standardized tests can not replace experience and quality workmanship.
