The General Electric Magne-Blast product line was produced with a wide array of shapes, sizes, and ratings. Finding interchangeable breakers can be simplified once you break the line down to a few simple rules.
The secondary coupler or secondary disconnect is a device/plug that carries the power that controls the breakers opening and closing circuits. The original breakers are equipped with 2 round, 7 pin couplers that mount on each side of the mechanism. The newer breakers have a single square coupler with 16 pins that mounts on the left-hand side (as you face the breaker). These two breakers are not interchangeable.
Older breakers are equipped with a large closing solenoid that closes the breaker, this mechanism type typically has an “MS” designation, like MS-5, MS-7, MS-10B1, or the most common designation MS-13. Newer breakers are equipped with a spring charged/stored energy mechanism, most commonly, the ML-13. This mechanism uses a motor/gearbox to compress springs that are released to close the breaker.
The primary advantage of the stored energy mechanism is that it draws much less current to close the breaker. These breakers have a limited interchangeability. More modern ML-13 breakers can sometimes be used to replace old MS style breakers. When produced at the factory, these replacement breakers will have a “C” at the end of the model number (e.g. AM 4.16-250-6C). Minor changes will also need to be made in the cell wiring when using this replacement because of the decreased power that it takes to close the breaker.
The next thing to look for is the MVA rating of the breaker. This is designated in the model number after the voltage rating e.g. AM 4.16-250-6C, is a 250 MVA rated breaker.
The smallest of the product line is the 18-inch wide 50/75 MVA breakers. Designated as either AM 5-MVA or AM 4.16-MVA, these breakers all had one of various vintage MS style solenoid mechanisms. They are available in 600-amp and 1,200-amp frames and are backwards compatible. For example, an AM 4.16-75 1,200-amp breaker can be used in place of an AM-5-50, but not the other way around.
The next step up are the 100/150/250/350 MVA breakers. These are built on slightly wider, 26-inch frames and are very common in commercial and industrial facilities. They have the same limited backwards compatibility of ML-13 to MS-13 mechanisms outlined above and all but the 350 MVA have a backwards compatibility of MVA, as well. In other words, a 250 MVA can always be used in place of a 150 MVA but not the other way around. The 350 MVA’s are built on a taller frame and are unique.
The larger 36-inch-wide breakers cover both the 7.2 kv and 13.8 kv range which are not interchangeable with each other, but generally carry the same interchangeability of their smaller 5kv brethren. The exception comes in the 750 MVA frames. The original 750 MVA (e.g. AM 13.8-750-2) is on a much taller frame than the 500 MVA or below breakers and is commonly known as a “tall boy.” Its added height is unique. However, GE did make a replacement later in production that is designated with an “L” at the end of the nameplate, AM 13.8-7505HL, which indicates a shorter lower profile breaker that was factory modified to fit into the ‘tall boy” cell.
The final breaker, the AM 13.8- 1000 is unique and not interchangeable with the others. There are two basic versions the AM 13.8 100-3H and 4H. The “3H” is commonly called the humpback breaker because the box barriers and arc chutes are taller in the back. The “4H” has smaller arc chutes and is interchangeable with the “3H”, but again, not the other way around.
Always make sure that breakers are replaced with replacements of the same frame size or extensive damage could result.
Trying to find a way to extend the life and reliability of your GE Magne-Blast switchgear instead of looking for a replacement? Learn more about how NPE’s bottle repotting program can be just what you need. If you need help identifying Magne-Blast circuit breaker designations, read this post to find out where to look.
Finding old or obsolete General Electric circuit breakers can be challenging. GE has produced circuit breakers for over 70 years, which can make it difficult to match the right models and model numbers to your needs. In this article, we’ll present a brief history of GE’s circuit breaker production and help you understand how to identify what circuit breaker you’re looking for.
GE’s “Slate back” line of type AE and AL air circuit breakers was its first product line utilizing one of the first true inverse time elements to obtain automatic “resettable” overcurrent protection. This marked a huge step up from simple fused protection. Sometime later, technological improvements prompted a redesign so GE introduced the AK line of breakers. These models featured improved electro-mechanical trip units and were designed to fit both AKD and AKD5 switchgear.
In the 1980’s, GE redesigned the AK line and gave the product line the AKR prefix. Although they may initially seem similar in appearance to the older style, the design has been improved and is not interchangeable with previous versions. This product line was designed to fit both AKD6 and the later redesigned AKD8 switchgear.
Almost all of the digits in an AK or AKR model number identify important characteristics of the breaker. It is important to either understand these details or even more important make sure your supplier does. Let’s use an AK-25 circuit breaker as an example. At a glance, with the door closed, most AK-25’s look the same, but the missing digits between the AK and 25 reveal important information that is needed to assure a safe and proper fit. You can use these quick guidelines to identify the specific model of a General Electric circuit breaker:
In addition to knowing the brand and product number you’re looking for, here are some other questions to help us identify the perfect solution for your needs:
To download this chart click here: flowchart for AK and AKR circuit breakers for guidance. If you’re still having trouble or are unsure of what you need, just let us know and we’ll be happy to walk you through the process.