Medium voltage load break switches control power to circuits with voltage ratings from 1kV to 52kV. They are used in a variety of applications and are differentiated from non-load break switches because as the name suggests they can safely be opened while power is flowing through the cricuit that they are installed in.

Applications include:

• Selector Switches - Sometimes called A-B switches which select which power source will be used to energize the primary of a transformer.
• Power Distribution - A group of switches, can be with or without a main, which direct power to various locations in a factory or other large facility.
• Primary - For a single transformer powering a secondary switchgear.
• Isolation - To de-energize equipment not being used or so that the switchgear can safely be serviced.

Typical ratings for the most common switches used on a 2.4kV through 15kV will have a continuous rating of 600 amp but are most often fused well below that.

They can be designed for use both indoor and outdoor and are used to interrupt the flow of power under both normal and emergency situations. They are most often operated manually but some are also equipped with a motor driven mechanism with a shunt trip which allows them to be opened and closed remotely.

The components of a medium voltage load break switch include the switch body and housing, contacts and mechanism and arc extinguishing medium. The arc extinguishing medium can be air, vacuum of SF6 (sulfur hexafluoride) gas. Vacuum and SF6 gas are used when a medium is needed to provide effective current interruption with minimal contact wear. Air is a cost effective option, especially if the switches will see minimum cycling.

As with any mechanical or electromechanical device, regular scheduled maintenance is required. This includes visual inspection, lubrication of mechanism and contact joints, testing of insulators and conductivity testing of the closed switch to ensure minimum internal resistance. Frequency of this maintenance will vary depending on factors including frequency of operation and environmental considerations. Failure to properly maintain these switches can and will result in non-scheduled power outages with damage to surrounding property and can injure or kill personnel in the area.

Many switchgear installations are in service well past the time that the OEM stopped supporting them or items may have long lead times which will extend the time of the unintended outages causing loss of production that run into tens or hundreds of thousands of dollars. This makes your local used equipment dealers like National Power Equipment invaluable. NPE not only has switches and parts in stock and available for quick shipment but also the experience and knowledge to guide you through pitfalls in things like parts interchangeability that wouldn't otherwise be apparent in the field. As always, knowledge and information is critical. Gather not only nameplate information but photos of both the overall switch and details of the parts in question. This will make it much easier for NPE to live up to its motto of "The right part, at the right price, right now!"

Many say that we are currently in a recession, others say not yet but one is due to hit soon. Either way we are all dealing with rising prices, longer lead times and shortages in available equipment. At NPE, we are here to help recession-proof your business.

Here's how we can help!

* Used, reconditioned equipment is at least 40%-60% less expensive than buying new.

* Used, reconditioned equipment is always quoted from available inventory so there are no supply chain issues.

* All reconditioned equipment is tested and warranted for up to two years! That's longer the manufacturer warrented it as new!

National Power Equipment specializes in:

Pars for Equipment Maintenance and Repair- We can support you with parts and supplies to keep your breakers, switchgear and medium voltage starters safely maintained and running for years to come. Many of the most problematic parts are available online at Aftermarket Parts Store for Replacement Circuit Breakers or Switchgears (npeinc.com) Many of these parts are available as new and upgraded by NPE (or one of our partners) to eliminate the defect that caused the problem in the first place.

Increase Capacity - As your business grows we can help your switchgear grow with you! From simply supplying a breaker for a future cell or adding and entire unit substation we have the equipment and expertise to help you expand economicly and without down time. Circuit Breakers, Relays, Transformers National Power Equipment (npeinc.com)

Equipment Upgrades - Solid State trip upgrades with reputable companies, such as Utility Relay, are one of our many specialties. Do you need to upgrade the ampacity of a line from say 1200 amp to 2000 or 3000 amp? We have the parts and experience to help there, too! Reconditioned Equipment (npeinc.com).

Rentals and Exchanges - With an inventory of literally thousands of breakers in every configuration, we can help you avoid longer term outages and stay up and running by purchasing upgraded and warranted breakers and equipment and swapping them out with your existing breakers, then return your original back to us for credit for the core. Quick Ship Inventory for Reconditioned Circuit Breakers & Switchgears (npeinc.com).

Technical Support - With decades of hands-on experience, literally 1,000's of breakers on hand for reference and huge online library of technical manuals and renewal parts books. Just give is a call and we will figure it out! Circuit Breakers, Relays, Transformers National Power Equipment (npeinc.com).

As Bob Dylan said, "The times they are a-changin'!" but that doesn't mean change has to be bad. With NPE's inventory, staff and decades of experience, we can all navigate these economic changes and grow.

Give us a call 1-800-647-0815 or send us an email info@npeinc.com and let us know how we can help you.

Remember, at NPE our motto is "The Right Equipment, at the Right Price, Right Now!"

Almost every day we receive an inquiry for switchgear, air and vacuum circuit breakers and related parts because the customer just got notice from the OEM  that their order has been delayed by weeks or even months due to "supply chain issues". These issues have become a fact of life and effect everyone, everyday regardless of industry, right? Wrong!

How NPE Helps Businesses Beat the Switchgear Shortage

When you deal with a company like National Power Equipment (NPE), there are NO supply chain issues! Everything we quote is on the shelf waiting for an order. We generally ship the same day or next day. Custom orders may take a little longer, but still are a fraction of the time versus OEM orders and are a fraction of the cost of new! 

NPE has thousands of used air and vacuum circuit breakers, tons of switchgear and tens of thousands of related parts all in stock. Each order has a money back guarantee and reconditioned equipment has a 1-2 year warranty.

In short, NPE has:

     Equipment is IN STOCK and ready to ship 

     Never had a supply chain issue

     Expert staff that will guide you through finding the proper equipment for your application

     Inventory that is updated daily and searchable online at www.npeinc.com

So give us a call, send us an email or search or inventory online. Find out why our motto at National Power Equipment, Inc. is "The right equipment, at the right price, right now!"

Westinghouse made a design change to the DB circuit breaker line about mid-way through production with the addition of a "test position" for the circuit breaker while it is in the switchgear. The original design, now designated "single position" only had a provision for the breaker to be secured in the cell while it was engaged to the primary buss stabs. Once withdrawn from the buss stabs the breaker would simply slide out of the cell on its rails. The new improved "3 position" breaker and switchgear had a provision for the breaker to be engaged on the buss stabs, withdrawn from the buss stabs but in a stable locked "test" position on the rails or disengaged to be withdrawn. This new test position allowed for safer lockouts during service among other things.

One of the most common questions we ask people when they are looking for a DB vintage circuit breakers and parts is, "is it a single or 3 position breaker?" If a photo of the breaker isn't available, and because it isn't listed on the nameplate, there are a series of questions we've developed to help identify the breaker style, assuming they have seen the breakers.

                                                                                    DB Single Position

                                                                                         DB 3 Position

The most obvious question is "does it have a movable or fixed escutcheon (faceplate)?". The 3 position breakers all had movable escutcheons so the switchgear door could be closed with the breaker in the test position.

If that doesn't help, the next question is "how does the breaker close and trip?". This works for about 99.5% of DB-15, DB-25 and DB-50 breakers. Single position breakers close by turning the handle clockwise a quarter turn and trip by turning the handle counter clockwise. 3 position breakers close by turning the handle clockwise and trip by pressing a rectangular trip button directly above the handle. 

For larger frame DB-75 and DB-100 breakers, which are all electrically operated, you need to look for the movable escutcheon plate vs. a flat front, or when looking at the cell, the window in the door is much smaller on a 3 position, approximately 5" x 7" whereas the single position is wider and taller to expose the whole front faceplate of the breaker.

EXCEPTIONS TO THE RULE!

Stationary/fixed mount breakers are always single position.

When someone needed a replacement breaker for a single position during the "3 position breaker era", Westinghouse would modify a 3 position breaker to what we call a "new style single position", it used the same handle as a 3 position, but they added a round trip button at about 2 o'clock above the handle. This accounts for the other 0.5%.

Other things to know...

There was an option for 3 position breakers to have a "spring assist" mechanism. This spring greatly aided the speed at which the breaker would close. This is available for DB-15, DB-25 and DB-50 only. Non-spring assist 3 position breakers are interchangeable. DBL(fused) breakers are always 3 position.

Field breakers designated DBF-6 and DBF-16 are usually 3 position, but it's worth double checking. Single position field breakers would normally be designated DB-25F and DB-50F.

Field modifications by end-users are always a possibility. I saw one line-up of single position breakers that an engineer had modified by removing the series overcurrent trips and bolting fuses in their place. Without single phase protection, the breaker had no way to trip and the fault on one phase cascaded up to the main, but by then it had also caught on fire! When in doubt, pictures are the best solution. 

Over the years, NPE has identified many parts that have design defects, that are no longer made, and/or are hard to find. It makes little sense to replace a defective, damaged part with another part with the same inherent faults, and you certainly do not want to wait weeks to get it. That is what the NPE Product Improvement Center (PIC) and its Aftermarket Parts (Aft's) list is focused on...having what you need, when you need it and often at times, at a better price point. 

Sometimes, it's about an improvement such as using moden, fiber-reinforced plastics as used for our DB Control Relays or simply a design change to improve strength as with our VB/VB1 Secondary's and DS Secondary's or just by having it in stock when you need it and at a better price than the OEM, that's if it's even still available. Currently, we have over 300 items on our Aft list. All of them are in stock, when you need them. They are available to order 24/7 online or through your normal purchasing channels.

If you don't see what you need, let us know! We are always looking for new ideas and ways to add to our ever-growing Aft list!

Just one more way at NPE we live up to our pledge...The right part, at the right price, right now!