Buy EHD3070 Westinghouse Molded Case Circuit Breaker
The arc chutes for molded case circuit breakers and old power breakers look simple enough, but they actually are a complex design and perform extremely important functions. For excitement, read the patent application for an old circuit breaker arc chute, if you can stay awake. MIDWEST sometimes is asked to explain what an arc chute does. We always go for the short version. Basically an old or new circuit breaker arc chute stretches the arcing that takes place when a circuit breaker opens, such that the arc is too long for the voltage to keep it going. Arc chutes have arc dividers in the form of flat segments stacked one above the other, with an air gap between them. When the arc occurs, it is expelled into the arc chute and into the arc dividers, such that it wraps back and further between the arc dividers. The wrapping back and forth around the arc dividers effectively stretches the length of the arc until it is just too long for the voltage to keep it going. When this happens, the arcing stops. The arc has been extinguished. When the circuit breaker opens, the main current carrying contacts open first and a different set of contacts, the arcing contacts, open second, such that the arcing contacts endure limited damage from the arcing, until the arc chutes interrupt the arc. So the combination of the arc chutes and the arcing contacts protect the main contacts from arcing damage when the circuit breaker opens and when it closes. When a circuit breaker is closed, the arcing contacts close first, again taking on the arc such that the main contacts are protected from arcing damage when closed. This is especially important when the circuit breaker interrupts a high current fault and there is a real blast in the arc chutes. Each phase, ie pole, of a circuit breaker has a separate arc chute. This is pretty much how the arc chutes of obsolete, old, and new replacement circuit breakers operate. So the arc chutes perform an extremely important function.
MIDWEST recently sold a 2500 amp 15 Kv old used air circuit breaker for $5000.00. It was in excellent condition and years ago it would have sold for $25,000.00. One might think the reason for the big drop in price is because of the age. But the biggest reason is the use of vacuum technology in 15 Kv class circuit breakers. Vacuum breakers are used to replace air circuit breakers in new 15 Kv switchgear. And many old medium voltage air circuit breakers have been replaced with new vacuum breakers or retrofitted with vacuum technology.
Maintaining and Testing 5 Kv and 15 Kv vacuum circuit breakers is a lot easier than the old air circuit breakers. And the vacuum breakers are a lot easier to handle. An old or obsolete air circuit breaker could weigh 1500 pounds. The new vacuum equipment is half that. The biggest difference is the simple replacement of the old heavy arc chutes with the simple vacuum bottles. For an historical perspective, the early 1900s saw the use of big old oil circuit breakers. The mid 1900s began the use of air circuit breakers. And the late 1900s began the use of vacuum breakers. MIDWEST has worked on all of them and the vacuum breakers are just so much simpler to service. Some older electricians and switchgear service technicians do not trust the vacuum circuit breakers as a safe circuit open device. I wouldn’t trust vacuum circuit breakers or old air circuit breakers or obsolete oil circuit breakers as open circuit protection. The circuit breaker must be racked out and, of course, the circuit grounded before any circuit work or equipment maintenance. By racking the breaker out, one has a “visible open.” Medium voltage air circuit breakers are an example of equipment becoming obsolete long before they actually wear out, all due to new technology.
During our annual Thermographic Scan of a large manufacturer’s electrical system, MIDWEST found a serious problem with a new circuit breaker. The middle line side bolted connection was extremely hot. They had recently installed a replacement circuit breaker with a higher interrupting current level in this panelboard. During their Arc Flash Hazard Analysis they discovered several old circuit breakers that did not have high enough interrupting current rating for their system. So they replaced these circuit breakers. The replacement circuit breakers had high interrupting ratings and it was a straight forward replacement project. Their electricians were pretty sharp, so they were skeptical of our finding. On third shift they powered down and checked connections and the electricians informed MIDWEST, in their own emphatic vernacular, that the bolts were tight and maybe MIDWEST was loose. MIDWEST has run into this breaker problem before. It doesn’t happen often, but we work with old and new circuit breakers every day, all day. Here is the work practice one must follow when changing out old circuit breakers. Always lay out the bolts removed from the old circuit breaker such that you know exactly which bolt came out of which hole. Use identical replacements for each bolt and pay attention to the bolt lengths. Replace the bolts with new bolts of the exact same length. On their installation, the middle line side bolt was shorter than the other two bolts. The middle bolt was not a through bolt. The bolt hole bottomed out. They used a bolt that was ¼ inch too long and even when it was properly torque tightened, it still was not a physically tight connection, because the bolt hit bottom before the attached bus was tight. We suspect their torque wrench was called “armstrong,” so we were sure they had tightened it enough. Again, on third shift, they replaced the bolt with the right length and the overheating circuit breaker problem disappeared. MIDWEST recommends following a simple work practice when installing replacement circuit breakers. Keep track of exactly which bolt went where. Usually it does not make a difference, but one in a hundred does. This customer was lucky we did an infrared scan shortly after the circuit breaker was replaced.
How is it possible that a very small replacement circuit breaker, weighing only 2 pounds, would cost over $500 when a large replacement power circuit breaker weighing 200 pounds might be less than $1000? MIDWEST frequently gets questions similar to this one. The basic answer is economic supply and demand, the most fundamental law of a market driven economy. A crude paraphrase would be “If the supply of a product goes down and the demand for the same product goes up, the cost of the product will increase.” There are more people chasing fewer available goods, or circuit breakers. In the world of supplying replacement circuit breakers, there are some small breakers that are no longer manufactured and are very rare, very difficult to find in the secondary market of used, reconditioned, and obsolete replacement circuit breakers. For example, there are small molded case circuit breakers that you can hold between two fingers, but they cost over $500. These breakers are no longer made. They are fairly common in some manufacturing facilities, but they are just not available. There are very few of them for sale and they are becoming scarce. This is classic low supply and high demand. On the other hand, there are large circuit breakers that are so common that they are not worth much more than scrap value. A zillion of them were made. Although they are no longer manufactured, they are a “dime a dozen,” so to speak. The supply is so large that it far exceeds the demand.
The high cost of rare replacement breakers is supported by the fact that they are still far less expensive than replacing an entire power panel. The high cost may seem unreasonable to someone purchasing an item for the first time. However, human nature would tend to look at the cost of a rare item as being too high, but not think of the cost of an abundant item as being too low.
Frequently MIDWEST maintains and tests old and obsolete circuit breakers on the customer’s site. And frequently the customer has their electricians or outside electricians remove the breakers from service and bring them to our breaker testing setup site. We are strong advocates of maintaining old and even obsolete circuit breakers. In addition to routine or textbook procedures, we have additional special maintenance services on older equipment. This is especially true when outdated breakers have obsolete overcurrent devices. We know how to repair many of the common deficiencies that we find in old breakers. But there is one common defect that suggests one may do more harm than good by removing breakers to test and maintain them. This occurs when insulating components, such as the old plastic or Bakelite supports for control disconnect fingers, are broken by the manhandling required to get the breakers out of their enclosure, to the test station, and back. We instruct the electricians on the cautions necessary, but it can be a challenge if you’re hauling a 150 pound breaker down a staircase. And many times these vulnerable components are installed on the breakers at “just the wrong place,” like on the bottom of the breaker where you don’t even see them, unless you know they are there. MIDWEST is extremely careful and we know what can happen, so we are better equipment to prevent problems. But there are some obsolete breakers located in such miserable areas, that one could nearly guarantee more damage is going to be done by the customer’s riggers or electricians moving the breakers than the typical deficiencies we find from the routine testing and maintenance services. It may be better to maintain the breakers in their substations and not haul them to a separate test site. This problem usually occurs when old or obsolete breakers are high current tested and the test equipped can not be located near the switchboard.
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.
10. If you haven’t discovered the great value of used circuit breakers you really should.
9. The Karma given off from a used circuit breaker purchase pays rich dividends. You’ll have to experience it.
8. Think of the future. Used breakers are of course green. The carbon credits you accumulate in this life do transfer to the next.
7. Buying used circuit breakers saves time getting to work. Think of the time you’ll save walking from your car to your building with your new employee of the month parking spot.
6. Buying used breakers puts you in good stead with your significant other. No longer will you spend wakeful nights thinking about ways you can save your company money.
5. Our used circuit breakers meet national testing standards.
4. Our used circuit breakers are readily available. Manufacturers do not keep inventories of used breakers. Your breaker will be in your hands just as fast as preparation time allows.
3. Our used circuit breakers are fast and easy to purchase. Check out our web site at www.swgr.com to see how easy it is.
2. Only used circuit breakers can fit right in as a replacement for out of production panel board or cubicle configurations.
1. And the number one reason to buy used circuit breakers is it saves money, up to 70% off the cost of new.