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Westinghouse DB Single Position vs. Three Position Circuit Breakers

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 Once withdrawn from the buss stabs the breaker would simply slide out of the cell on its rails. The new improved "3 position" breaker and switchgear had a provision for the breaker to be engaged on the buss stabs, withdrawn from the buss stabs but in a stable locked "test" position on the rails or disengaged to be withdrawn.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.


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. 

The NPE Product Improvement Center and Aftermarket Parts

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!

AKD Switchgear and Breaker Interchangeability


When General Electric came out in 1946 with the AKD breaker and switchgear line, it represented a shift forward to a newer emerging technology. Moving away from oil filled dash pots and breakers mounted to pieces of slate of various sizes and very little standardization of buss configuration, AKD switchgear and breakers were a much-needed step in the right direction. 

Highlights of the product line include:

     Standard frame sizes of 225, 600, 1600, 3000 and 4000 amps.

     Individual poles mounted to a standard steel frame for each frame size.

     Electro-mechanical type EC1 trip units which relied on spring tension to set up and adjust trip settings.

     A mechanical levering in mechanism to aid the operator in installing and removing draw out elements from the cabinet.

     Typical model numbers designated each frame size. 

          AK 1 15 for 225 amp

          AK 1 25 for 600 amp

          AK 1 50 for 1600 amp

          AK 1 75 for 3000 amp

          AK 1 100 for 4000 amp

The designation of 15, 25, 50, 75 and 100 indicates the breaker's potential ability to interrupt a fault in amps, for example and AK-1-50 is a 1600 amp maximum continuous amperage frame that would interrupt up to 50,000 amps in a fault. While the example,  AK-1-50 was designed to run at a continuous 1600 amps load, often EC1 trip units would be installed with lower ratings and would allow engineers to derate individual breakers to say 600 amp and 800 amp, while still maintaining the 50Ka interrupt rating.

Dash numbers at the end of the model number indicate vintage changes which may change on board parts interchangeability but the breakers themselves, aside from the specific size of the EC1 trip units are all interchangeable. For example, an AK-1-25-1 may not look like an AK-1-25-9 but they are completely interchangeable if they have the same trip unit installed.

In 1955 General Electric made improvements to the product line but kept the newer breakers interchangeable with the older breakers.While still considered type AKD switchgear and breakers, the breakers themselves had a name change to AK-2-15, AK-2-25, AK-2-50 and so forth. Minor improvements came with the series overcurrent trip units which are now called EC2 and EC2A, but the major improvement was a spring charged mechanism which allowed for much faster opening and closing of the breakers and improved contact structures making them more reliable. The levering in mechanism also changed but while they might look different, they remained interchangeable with the older AK-1 series breakers. The other major technology improvement cam from the option of adding fuses to each individual pole which improved the interrupt ability of the breaker to 200,000 amps regardless of base frame size. The designation for these breakers added an "U" to the model number, such as AKU-2-25 and AKU-2-50. The switchgear for these fused breakers was specially made and while still considered type AKD breakers, they have no interchangeability with the older AK-1 style breakers. GEH-1830A Manual



       AK-1-25                                                               AK-2-25

In 1960, improvements and changes to the product line include AKD 5 switchgear around with breaker frames designated as AK-2A-25, AK-2A-50 and so forth. These are often confused by field technicians who miss the detailed model number and just refer to the breaker as an AK-25 or an AK-50. The best way to specifiy any of these breakers is in a series of photos which include a shot of the breaker overall, one of the trip unit and one of each nameplate (there are two on electrically operated breakers). Also, list any known extra accessories, for example, an undervoltage trip, a bell alarm or send photos showing them. GEK-7302 Manual


               AK-2-25                                                      AK-2A-25

When this information is relayed to your sales team, at National Power Equipment, you can be sure that you will receive "The right equipment, at the right price, right now"!

Air and Vacuum Breaker Maintenance for Peak Reliability

     Modern air and vacuum circuit breakers are an integral part of all industrial and commercial electrical systems. Failure of just one of these breakers can have far reaching ramifications for both production and finances. Preventing these failures is the goal of any good maintenance program and consists of two basic layers:

1. Regular preventative mainteance (PM) programs not only add reliability to your system but can also point out potential problems so they can be proactively dealt with in a cost effective manner. Nobody wants "unscheduled" outages because a component has failed and as a result, damaged other equipment in the process and interrupted production. PM programs can be scheduled around production schedules (holidays, weekends, nights...) and include a basic clean and test work scope in which breakers are cleaned, lubed and tested for insulation and contact resistance, primary or secondary injection of the trip units. Frequency of these schedules is also dependent upon the ambient conditions that the switchgear and breakers are exposed to. There is a big difference between a paper mill and a hospital environment. This work may be able to be performed in the field, but it is best handled in the controlled conditions of a quality shop that specializes in this work.

2. Remanufacture and or retrofit offers significant life extension and reliability of your air and vacuum circuit breakers. It differentiates itself from a PM program in several ways. The primary difference is work scope. A remanufacturing program like NPE's "Class One" program includes a full disassembly and inspection of each individual component, right down to the last spring and washer. Once inspected, the components are cleaned and plated according to the components use. Current carrying parts are silver plated and mechanism parts are generally zinc plated, although there are a few minor exceptions like phosphate plating. Painted parts are stripped to the base metal, primed and painted, the wiring is replaced with fresh SIS wiring customized to the existing prints. Replacement parts are available from our inventory if used and aftermarket parts with little or no delays to the rebuild. Also, now is the time to replace solenoid coils and rewind motors as needed and upgrade low voltage breakers to a modern solid state overcurrent trip system like Utility Relay's AC Pro or AC Pro II. This type of work scope cannot be done in the field and typically involves shipping to a facility like NPE for a 4-6 week turnaround. Any good remanufacturing program will provide you with test reports indicating that the breaker is ready for service and a warranty. NPE is so confident in its rebuild program that it has extended the industry standard one year warranty to two years.





Having an integral part of your infrastructure out of service for four to six weeks can be a major hurdle to overcome for many facilities. Ideally, a spare breaker should be on hand for each application and swapped out as needed for remanufacture and upgrade, but many facilities may not have adequate spares on hand. That is where a stocking distribultor like NPE can be a beneficial partner. NPE has the inventory to either provide spares for your swap out program or we can rebuild breakers out of our inventory and swap them for yours during the change out.

     Still not sure what to do? As someone once said, you always have three choices..."the right choice, the wrong choice and no choice; and the last two are the same thing", of the three options, which do you choose? If you choose the first one, give us a call or drop us an email, we'll be happy to discuss your issues and provide a long or short term solution. Otherwise, we'll probably be hearing from you after choice two or three kicks in!

NPE - The right choice, the right price, right now! 




Used Switchgear Market Growth Forecast


Traditionally, the used equipment industry and especially the market for used switchgear has been thought of as being counter recessionary. The common wisdom being, customers will spend money to maintain and upgrade old equipment rather than buy new to save money and to avoid the long lead times associated with purchasing and installing new switchgear.

Recent growth in manufacturing and our economy has changed this dynamic and now used switchgear, circuit breakers and parts have seen a surge in sales that looks to continue well into the future. We see the driving forces behind the growth as:

  • Increased demand for products pushes manufacturers to restart old production lines and push them to new limits.
  • Much of the switchgear that powers these lines are no longer supported by the original manufacturer because of the planned obsolescence. This creates increased demand for used and aftermarket solutions. NPE AFTERMARKET PARTS
  • Used and aftermarket solutions are typically 40-60% less expensive than purchasing new equipment, and they are available much faster and generally carry the same or better warranty as new. To add to this, the fact that personnel are already familiar with how this switchgear operates and you have a win-win scenario.
  • Increased cash flow from the economic upturn allows for maintenance and upgrades that had been previously deferred.
  • Regular maintenance and testing of switchgear and breakers will increase the life span of the equipment by decades. Older technology can be easily upgraded with options like arc flash protection, ground fault and communications. All these factors will reduce down-time and unscheduled outages.
  • For Field Service Specialist - servicing switchgear that has been obsoleted by the manufacturer will also serve as an opportunity for companies to provide other equipment and other services that field engineers can alert them to. Having your people in a plant, actively promoting your products is the best advertising you can get. 
  • Older switchgear can be repaired and upgraded to meet new demand. Many of the new products are sealed and unable to be repaired. As a result, repairs or upgrades that would cost a few hundred or few thousand dollars, and cannot be performed and users are forced to discard equipment and purchase new replacements for tens of thousands of dollars and potentially long lead times. 
  • Many customers are realizing that planned obsolescence will also render new installations of the latest whizz-bang technology obsolete, the same way their current equipment has been treated. Maintaining and upgrading current equipment just makes sense.

The bottom line is that just as a rising tide raises all boats, as the economy grows and thrives, so will the demand for used equipment dealers like National Power Equipment, where our motto is, "The right equipment, at the right price, right now!" Whether you are an end user, in the repair industry or a dealer, we strongly recommend you prepare for double digit growth in 2021 and the years that follow.