As discussed in other articles on this site, care and maintenance of the primary disconnect (bottle) assembly in your GE Magne-Blast switchgear is a critical element that ensures proper functioning for years to come. Performing this critical maintenance can be tricky to do in a cost-effective manner if you are not intimately familiar with the equipment. Fortunately, we specialize in this area.

The Two Routes for GE Magne-Blast Maintenance

Remove and Rebuild

The first maintenance option is to remove the bottles from the Magne-Blast gear—either one breaker at a time or in mass—and then have them rebuilt in a proper fixture (to ensure proper alignment) using modern materials that ensure proper functioning for years, if not decades, to come. Performing maintenance in this manner can become time consuming from both a labor and an outage standpoint since each breaker will be taken out of service and will remain that way for at least a week or more depending on labor and outage schedules.

Swap Them Out

The second option is to purchase bottle assemblies that are already rebuilt and tested and have them swapped with existing equipment in one outage. The cost savings in downtime and mobilization costs for labor are obvious. However, you will need a supplier like NPE with both the experience and the inventory necessary to ensure that the replacement bottles you acquire match the existing ones, making them interchangeable without modifications in the field. GE has published very little comprehensive information on this subject. The attached diagram is often thought to be an all-inclusive guide, but our hands-on experience has shown that there are many more styles and factors that can affect interchangeability.

Getting the right information to your switchgear dealer is fairly simple, but it does require an outage. You will need to remove the inspection covers and get detailed, well-lit photos of the copper details at the top of both the line and the load side bottles, as well as photos of the bottom side by the shutter. Also, you will need to document the model number and the frame size of the breaker that will be installed into the cell. The feeder breakers are often the same configuration, but care will have to be taken with the main and ties breakers and document them separately.

Once the proper bottles have been identified, rebuilt, and swapped out, the existing bottles can be rebuilt and kept on hand for future spares or, if they are in rebuildable condition, they can be returned for credit as cores.

If it’s time to maintain or replace your Magne-Blast Switchgear primary disconnects, NPE can help. Learn more about how NPE’s bottle repotting program can be just what you need or just contact us today to talk to one of our experts.

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.

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!

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

There are multiple factors that you can check to determine whether a General Electric Magne-Blast circuit breaker is interchangeable or not. These include:

• Single coupler vs. double coupler
• Solenoid vs. stored energy
• Voltage/MVA Rating
• Frame size

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. You can tell the difference between original and newer breakers by the following characteristics:

• 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

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.

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. For example, the model number AM 4.16-250-6C is a 250 MVA rated breaker. These lines Magne-Blast circuit breaker product lines include:

• 50/75MVA
• 100/150/250/350 MVA
• 750 MVA
• AM 13.8-1000

50/75 MVA Magne-Blast Product Line

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.

100/150/250/350 MVA Magne-Blast Product Line

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.

750 MVA Magne-Blast Product Line

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.

AM 13.8-1000 Magne-Blast Circuit Breaker

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

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

• 600
• 1200
• 2000
• 2500
• 3000
• 3800

Need Help Finding Interchangeable Breakers?

Still confused? We can help. Take a photo of your nameplate and contact us or use NPE On The Go to get all of the information needed to get a quote 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.

General Electric produced a very popular line of medium voltage (2.3kv-15kv class) circuit breakers over a 30-year timespan with literally tens of thousands of units in service across the U.S., Canada, and other areas. This product line, known as the Magne-Blast or AM breaker, has been upgraded over the years with improvements and life extensions to add even more value to the customer.

One of the maintenance items that needs to be addressed periodically is what the industry calls the “Raise Lower Mechanism.” This is a mechanism that lifts the breaker from ground level and assures proper alignment and connection to the primary disconnects on both the line and load side.

Maintaining Raise Lower Mechanisms for Your Circuit Breakers

There are several versions of this mechanism that need to be identified properly when service is needed. First, we will address the two most common mechanisms, the “Cast” and “Fabricated” or “Fab’d” mechanisms. GE classifies these mechanisms into two groups depending on the width of the switchgear cabinets they are in because they also include the shutter and connecting chain. GE identifies the Cast Mechanisms as either M26H or M36H because the cabinets they go in are either 26” or 36” wide. The fabricated design is simply designated as M26 and M36.

There is a well-known table in a GE publication that details the supposed application of these devices with particular breaker models and frame sizes. However, we have found both discrepancies in actual field applications as well as contradictions within the table itself. See the Illustration 1 Cast vs Fab mechs pdf for reference.

The easiest way to identify which mechanism you may have (they are not interchangeable), is by looking at the housing at the top of the mechanism that contains the gears. The cast style is obviously heavier duty, thicker, and has pit marks from the sand that was used to sand cast the original parts. The fabricated style is built with plate steel that is lighter duty and welded together.
See Illustrations 2 and 3 for reference.

NPE regularly stocks both of these mechanisms. They are completely rebuilt and ready to install for those “unscheduled outages” and we can even take your damaged or worn out mechanism in for a core rebate. For customers that want to rebuild the mechanisms themselves, we offer both cast bushing kits and fabricated bushing kits and years of experience and expertise to help you along the way.

Raise Lower Mechanism Exceptions

While these mechanisms comprise 90% of what is found in the market, there are some exceptions that should be noted.
The first mechanism is designated in the first illustration with the “HH” suffix. These mechanisms will be found in the largest of the Magne-Blast product line, particularly in the 1000 MVA breakers. See 7A in Illustration 1 for reference. They are the heaviest duty mechanisms and have two vertical screws to lift these frames into place.

On the opposite end of the spectrum, the smallest Magne-Blasts made are the 50 and 75 MVA class and are built for 18”-wide switchgear. These cells utilize a single lifting screw mechanism mounted on only the right side of the cell.

The last group of mechanisms are the oldest versions made for the AM 5 and AM 15 versions of the Magne-Blast line that utilize a double secondary coupler. While not many of these breakers are left in service, there are designs for updated/retrofitted breakers that still use the old switchgear. This last set will have the double vertical screw on both sides, similar to the “HH” version, except that these are much lighter duty. When replacing these, you will need to know if the motor that operates the lift is mounted in the front of the cell or all the way in the rear.

Raise Lower Mechanism Aftermarket Parts to Help Keep Switchgear Going

In addition to Raise Lower Mechanisms, NPE manufactures and stocks many of the common parts that you will need to keep your switchgear running. Raise lower motors, motor clutch parts, and bearing kits are all the things you will need to properly operate and maintain your equipment. You can find these parts in our Aftermarket Parts Store on our website.

• AM 4.16 -350 3000 Amp Shutter (Cell)
• AM Motor Coupler
• AM Raise Lower Mech Bearing and Bushings Kit (Cast)
• AM Raise Lower Mech Bearing and Bushings Kit (Fabricated)
• AM Raise Lower Motor (120 AC/125 DC), with Switch
• AM Raise Lower Motor (120 AC/125 DC), without Switch
• AM Raise Lower Motor (220 AC/250 DC), without Switch
• AM Raise Lower Motor (220 AC/250 DC), with Switch
• AM Raise Lower Motor Base Plate

This may seem complicated, but at NPE we face these questions every day. Our knowledgeable staff has the expertise to walk you through the various steps to identify what you have. Contact us online, give us a call, or send us an email with pictures of the nameplate if available and we will help you get the right parts, at the right price, right now!

General Electric produced tens of thousands of Magne-Blast breakers in various sizes.

While most maintenance programs focus on rebuilding the original air breakers or retrofitting them to a more modern vacuum technology, there are other components to the system that need to be addressed to maintain safety and reliability.

Why Magne-Blast Bottles Need to be Repotted

The main component that needs to be addressed is the “bottle,” the critical link between the draw outcircuit breaker and its connection to the line and load side buss. The bottle consists of a porcelain cylinder mounted in a cast aluminum plate that is aligned and attached to the switchgear cabinet. Within that bottle is a silver-plated copper “tulip” that the line and load side conductors mate with for a solid reliable connection.

That connection is mounted in a filler material and supported by potting material that was originally designed to fill the upper void in the bottle and hold it in place for proper alignment. However, that material, commonly described as a tar pitch like filler, dries out and cracks over time. This allows moisture, dirt, and other contaminants into the bottle that cause that old reliable mating connection to loosen and eventually fail.

Those failures can be catastrophic, causing untimely loss of production and collateral damage, and can occur regardless of the care and maintenance of the breaker and the rest of the system. The question then is, “How do I maintain the reliability of this system”? Should I spend the capital for upgrades and replace the whole system?”

The answer is simple: Call NPE. We have the material and experience to eliminate this issue and help you extend the life of your Magne-Blast switchgear through our special repotting process.

NPE’s 8 Step Procedure: 

1.      Examine the bottles in a fixture and conduct a wipe test to assure that they are candidates for rebuild.

2.      Remove the outdated “tar pitch” potting right down to the filler.     
3. Re-align the connecting tulip and lock it in place so it doesn't move and cause future failures.
4. Secure the joint between the copper and seal.
5. Insulate the buss with modern shrink tube insulation.
6. Replace the old potting with a new 2 part system that is thermally stable which will last far into the future.
7. Clean and silver plate all mating surfaces to increase conductivity at critical joints.
8. Re-test alignment and conductivity to assure a quality trouble-free replacement in the field.

Sound simple? The devil is in the details and NPE focuses on details. This whole procedure may sound easy but there is typically little opportunity to schedule downtime to shut down production while these critical components are sent out for work. That process can take one or two weeks.

NPE stocks replacement bottles that can be matched to your system and swapped out in hours rather than weeks. Once we've provided identical replacements, we can evaluate the bottles that were taken out and either provide a credit for the "core" or we can recondition/repot them for replacement in other cells or to have on the shelf for spares for other GE circuit breakers.

Contact us online or give us a call at 216-898-2680 to discuss our Magne-Blast Bottle Repotting Program today.