Demystifying Dual Rated Magne-Blast Breakers

Dual rated Magne-Blast breakers have much longer model numbers than most and can be very confusing to laymen and professionals alike. There are not a lot of these breakers on the market and finding an exact replacement with the same long model number is not only impractical but not necessary either.

Breaking Down a Magne-Blast Dual Rated Breaker

A typical dual rated breaker would be, for example, AM 2.4/4.16-150/250-3. What does that number indicate and do you have to find a breaker with the same model number to ensure it will work? In a nutshell, this breaker is rated for 150 mva at 2.4kv and 250 mva at 4.16 kv. The confusion tends to clear when you realize that all AM 4.16 250 breakers are rated for 150 mva if operating a 2.4kv line voltage and 250 mva on a 4160v line.

A nameplate for a AM 2.4/4.16-150/250-3 General Electric Magne-Blast dual rated circuit breaker.

There is nothing inherently special about the breaker and any breaker rated 250 mva that follows all the other guidelines we discussed in other blog posts will also work. So, if you have an AM 4.16 250-4H will it work? Yes! How about an AM 4.16-250-7H? No, not without modifying it to fit in the older switchgear by converting it to a “C” breaker.

Care needs to be taken though because this AM 2.4/4.16-150-250 has a sneaky cousin, the AM 2.4/4.16-100/150. This breaker looks identical, but because it’s only rated 150mva at 4160 volts it should not be used in an application that calls for an AM 4.16 250 breaker. Of course, bigger is still better, so can you still use any 250 mva breaker in place of the 150 mva.

Still confused? Call us to talk to an expert or go to m.npeinc.com – a fast and easy way to get us all the correct information we need to give you a fast quote!

General Electric’s Magne-Blast Product Line and Interchangeability

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.

How to Determine if a GE Magne-Blast Breaker is Interchangeable

Single Coupler vs. Double Coupler

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.

Round style double couple Magne-Blast breaker.

Square style single coupler Magne-Blast breaker.

Solenoid vs. Stored Energy

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.

Magne-Blast breaker with MS mechanism.

Magne-Blast breaker with ML mechanism.

Frame Size/Voltage/MVA Rating

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.

Frame Size

600/1200/2000/2500/3000/3800

Always make sure that breakers are replaced with replacements of the same frame size or extensive damage could result.

Need Help Finding Interchangeable Breakers?

Still confused? We can help. Take a photo of your nameplate and contact us or just go to m.npeincom and follow NPE On The Go to get all of the information we will need to quote you a replacement.

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.

What Do Westinghouse Housing Codes Mean?

On some Westinghouse air breakers, a special code is stamped on the nameplates which causes some confusion when replacing and maintaining the breakers in the field. It is called the “Housing Code” and is designated with a single letter. Ironically, the housing code was originally intended to avoid the very confusion that it is causing today. So, what is a housing code—and more importantly, what do we use it for today?

Breaking Down Westinghouse Air Breaker Housing Codes

In the 1960s and early ‘70s, a housing code was the factories designation to indicate interchangeability between circuit breakers within the lineup of switchgear as it was produced from the factory. Let’s look at an example. If you have a double-ended lineup of Westinghouse type DB air breakers and it’s designed with 3,000 amp electrically operated DB 75 mains, A DB 75 tie with 2,500 amp trips, and 12 1,600 amp, DB 50 feeders and the feeder breakers have trip units rated 1,600 amp, 1,200 amp and 800 amp, you might have the following designations.

A Westinghouse DB75 air circuit breaker.

The DB 75 mains all have the same control wiring and trip units and are both mechanically and electrically interchangeable, so they would logically both have a housing code of “A” stamped on them, as would any spare breakers on hand. The DB 75 tie is unique to the lineup because of the smaller trip unit, so it would have a housing code of “B,” as would a spare breaker if it was built at the time of the purchase. The 1,600 amp frame feeders are all mechanically interchangeable but have three different-sized trip units so they are not electrically interchangeable, the 1,600 amp breakers would all have the same housing code of “C,” the 1,200 amp breakers would be “D,” and the breakers with 800 amp trip units would all be “ E.”

This system ensured that operators had an easy way to identify interchangeability when the switchgear was new. However, housing code designations effectively became obsolete over the years with modern solid state trip units. These new solid state trip systems are more effective and accurate and much more adjustable than the original series overcurrent trips supplied by the OEM. They allow breakers that are mechanically interchangeable to also be adjusted to be electrically interchangeable with other breakers in the same line up. These trip units can and must be adjusted by qualified technicians to ensure that each breaker is set to protect each load safely and effectively.

This housing code continues for breakers in the medium voltage class as well but is less complicated. For example, if there is a lineup with 2,000 amp mains and 1,200 amp feeder breakers, the 2000s would all be designated “A” and the 1200s all designate “B” because they are all mechanically and electrically interchangeable. The overcurrent trip function is controlled by current transformers and panel mount relays and are separate from the draw out elements.

A housing code for a Westinghouse air breaker.

NPE: Experts in Used and Remanufactured Air and Vacuum Circuit Breakers

Whether you need help identifying circuit breakers or finding the right switchgear parts for your facility, NPE can help. Our extensive inventory of parts and expertise has made us to-go source for solutions for switchgear and circuit breaker needs. Go to our NPE on the Go mobile site or contact us today to talk about your needs and how NPE can help.

What “Obsolete Circuit Breakers” Really Means

Websters definition
Obsolete
adjective
ob·so·lete | \ˌäb-sə-ˈlēt, ˈäb-sə-ˌlēt\
Definition of obsolete
a: No longer in use or no longer useful // an obsolete word
b: Of a kind or style no longer current, old-fashioned // an obsolete technology

NPE’s definition
As relating to switchgear and circuit breakers… A product line not supported by the original manufacturer, but still commonly in use.

Why No Switchgear Parts are Really Obsolete

Many factories, government facilities, and large commercial buildings are operating on switchgear that is no longer supported by the OEM. The lights are still on, production is running, and everything is fine, until it comes to light that new parts are no longer available. What should you do?

Switchgear is one of those systems that represent a large financial investment. It’s physically large and often located in a basement, or on a rooftop or mezzanine. This makes it difficult to physically remove it if you decide to replace it and represents a large commitment of money, labor, and more importantly downtime for the building and systems. That’s time and money that could be better spent elsewhere. The solution to this problem is to find what you need on the secondary or used equipment market.

An “obsolete” General Electric AK-2-25 circuit breaker that can be found on the secondary or used equipment market.

Where to Find Obsolete Circuit Breakers and Other Used Switchgear Parts

Used switchgear dealers are often looked at as the first responders of the electrical market. They are intimately familiar with the equipment that the OEMs have obsoleted and can supply you with quality circuit breakers and parts, reconditioned to the highest standards and often upgraded with the latest materials and technology. Best of all, equipment is available with little or no lead time keeping your facility and production up and running.

At NPE, we have a saying that “nothing is obsolete.” Not only do we have thousands of circuit breakers, switchgear, and parts in stock and available at a moment’s notice, we also offer solutions for over 250 of the most troublesome, hard-to-find parts. This gives you new aftermarket replacement parts with design and material upgrades to keep your switchgear up and running better than ever. Our inventory includes items that go back to the 1940s and our staff has the experience to provide cost effective solutions for repair, upgrade your equipment, and extend its useful lifespan almost indefinitely.

Need a solution for your switchgear problems? Submit information about what you need on our NPE on the Go mobile site or contact us today to talk about your needs and how NPE can help.

The Benefits of Renting or Exchanging Reconditioned Circuit Breakers from NPE

National Power Equipment is more than just the go-to circuit breaker supplier for used and remanufactured air and vacuum circuit breakers. In addition to selling breakers, NPE also offers a convenient rental circuit breaker program for facilities that either don’t have sufficient spare breakers or want to avoid down time caused by outages.

The reasons for needing rental breakers vary, but it typically involves when a facility reaches a certain point in its maintenance schedule or if a breaker needs to be fixed. When those times come, NPE can provide your facility with a rental breaker ready for service or set up a rental breaker exchange based on your specific needs and timeline.

A series of circuit breakers available for rent.

Rent Breakers Ready for Service

When you rent a breaker, NPE will make sure to have it ready to put it into service. NPE will work with you to meet your breaker specifications so that your rented breaker is completely interchangeable. NPE regularly keeps a “fleet” of low-voltage breakers in stock and ready to go at a moment’s notice, which means we can sometimes ship out your rental breaker the day it’s requested. If the breaker isn’t already in the rental fleet, we can typically recondition your required breaker and ship it out in three to five days. Stock rotates quickly, so make sure to check with us about availability.

Rentals are priced on a per-month basis, plus freight for shipping. NPE can work with you to not only determine which rental breaker options are interchangeable for your setup, but also which are the best for your budget. For example, manually-operated breakers are a less-expensive option than electrically-operated. In turn, we generally recommend manually-operated breakers for savings purposes unless the breaker is meant for use with a generator, transfer scheme, or other similar situations.

Rental Breaker Exchange

The rental breaker exchange program is a good option for service shop customers that don’t want to take on a series of outages. In this scenario, NPE provides used, EOK breakers that the customer can recondition and retrofit on their own. Once the customer is ready to swap out the breakers, NPE’s breakers are exchanged with the customer’s breakers during a single outage rather than several. This single exchange limits the amount of overall downtime and the labor involved with repeated exchanges.

Rent Circuit Breakers from NPE

Whether you need a short-term solution for a single breaker or want to swap out 10-15 as part of a maintenance schedule, NPE can provide you with a rental solution for your needs. Contact us today to talk to one of our experts about our rental program.