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

Breaking Down AKD Model Numbers Designation

The designation of 15, 25, 50, 75 and 100 indicates the breaker's potential ability to interrupt a fault in amps. For example, an AK-1-50 is a 1600-amp maximum continuous amperage frame that would interrupt up to 50,000 amps in a fault. While the AK-1-50 was designed to run at a continuous 1600 amps load, EC1 trip units would often 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.

Notable Improvements for AKD Switchgear and Breakers Over Time That May Affect Interchangeability

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 – 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 specify 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, such as an undervoltage trip or a bell alarm – you can also send photos showing them. GEK-7302 Manual

               AK-2-25                                                      AK-2A-25

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

GENERAL ELECTRIC LIMITAMP CLOSE COILS

OEM #: 1D300G102 115VAC / NPE Part #: 100002084

OEM #: 1D300G124 230VAC / NPE Part #: 100001714

OEM #: 1D300G144 230VDC / NPE Part #: 100002104

OEM #: 1D300G152 76VDC  /  NPE Part #: 100002094

Today, we are spotlighting the General Electric Limitamp Medium Voltage Motor Starter Close Coils. This part which has been custom manufactured through an exclusive contract with NPE, it is available in a variety of both AC and DC control voltages.

Please specify the correct voltage or part number when ordering. These listings and other General Electric parts can be found at: https://www.npeinc.com/ge-general-electric.

This part is often sold with a new Limitamp Pole Shader https://www.npeinc.com/ic-pole-shader, OEM Part #: 284A962P2 for contactors with AC coils and armatures. NPE P/N 100001444.

This product and all of the products in the Aftermarket Parts Store https://www.npeinc.com/aftermarket-parts can be purchased online or through your normal purchasing channels. As always, our motto "The right part, at the right price, right now!"

Part number used to reference original OEM's for identification purposes only. They are not manufactured, endorsed or warrantied by OEM.

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 line of medium voltage air circuit breakers called the MAGNE- BLAST for over 30 years. This product line was very popular and was produced in a wide range of sizes and ratings to meet customer’s needs.

Particular attention needs to be paid to several parts of the nameplate when you’re looking for replacement MAGNE-BLAST breakers or parts for these GE circuit breakers. This flow chart was designed to streamline the specification process and help you identify your MAGNE-BLAST designation.

Even with the flowchart, it can still be easy to miss specifics for designation There will be additional information that you will need. Rated Amps, close and trip voltage, and mechanism type can all be found on the nameplate. When in doubt, a photo of the nameplate and a photo of the breaker from the front will give your supplier a clear understanding of what you need. The following photos of MAGNE-BLAST nameplates show how important details like the letter suffixes are in determining exactly what you need.

Still confused? Contact us today or try our Mobile Ap- NPE on the Go  and we’ll help your figure it out. As a circuit breaker supplier, that’s what we’re here for.