General Electric AKR Circuit Breaker Nomenclature

Why can’t we just quote all possible options on an AKR-30?  We get that question a lot.  General Electric type AKR circuit breakers came in hundreds of configurations.   Oftentimes different AKR breakers will interchange with the only differences between different model numbers being the type of trip unit.  Other times, model numbers that appear to be close to identical correspond to drastically different frames.

Similar to AK circuit breakers, AKR breaker model numbers are set up as groupings of numbers and letters separated by dashes.  Here is a description of the different number and letter designations.  A table follows at the bottom of this article to serve as an overview.

AKR  -  6D   - 30H

AKR is the breaker type indicating that is a later model GE Low Voltage Power Circuit Breaker

The “6” in AKR-6D-30H refers to the type of trip unit on the breaker. Specifically in this case the “6“ refers to GE VersaTrip.   The list of trip types is listed in the table at the end of this article.

The “D” in AKR-6D-30H refers to the switchgear type that the breaker is made for (in this case for AKD-8 switchgear).  Different switchgear types utilized different rack-in styles and also different primary disconnect orientations and styles  The earliest AKR breakers were designed for type AKD-6 switchgear and their letter designation was “A”.   Later model AKR breakers were designed for type AKD-8 switchgear and were designated by the letter “D“.  Breakers designated for AKD-6 and AKD-8 switchgear are not interchangeable although many parts between the two are identical.  In general “A” breakers had shallow front covers (escutcheons) that were painted blue.  “D” vintage breakers had deep escutcheons that were painted black.  In addition to the “A” and “D” vintages, you can also see breakers with the letter “B” such as an AKR-5B-30.  Breakers with the “B” designation were sold with OEM cradle assemblies for non-OEM switchgear builders to use in their own enclosures.  In this case, you need to inspect the breaker to identify what type of switchgear the breaker is designed for because “B” breakers can have either shallow or deep escutcheons.  In addition, “B” vintage breakers can have rear primary disconnects that are of a different orientation than their matching “A” or “D” vintage units.  Similarly, in AKR-75 and AKR-100 breakers the designations of “C” and “F” are used to indicate the breakers were used in gear that wasn’t built by General Electric.  

The “30” in our AKR-6D-30H example refers to the interrupting capacity of the breaker and also to the breaker frame size.   In this case, the “30” tells us that the breaker has an 800 Amp max frame.  The “30” typically refers to the breaker having the capacity to interrupt 30,000 amps at 480 volt BUT in this case since it is followed by the letter “H” the interrupting capacity for this breaker is increased to 42000 amp at 480VAC.

There are numerous exceptions to the generalized rules above, most of which are easier to understand in the table below.  A few explanations of some of the more common breaker styles:

* AKRT:  Refers to an AKR-50 breaker that is rated for 2000Amp (instead of 1600Amp). 

*AKR-5A-50H: Refers to AKR breaker with a higher interrupting capacity than non-”H” units.

*AKRU:  Refers to a breaker with integrated current limiting fuses, AKRU-30 or AKRU-50.  If working with an AKRU-75 or AKRU-100 the fuses are mounted in a separate drawout fuse truck used in conjunction with a standard AKR-75 or AKR-100 breaker equipped with an anti single phase device.

*AKR-30S:  Refers to a Substructure breaker. AKR-30S breakers are considerably smaller than their AKR-30 counterparts.  Actually AKR-30S breakers are built on frames similar to the original AK-2A-25 breaker.

* AKR-30L:  Indicates breaker is extra high interrupt

* AKR-100E:  Indicates extra high interrupt

* AKR-5AE-30:  Utilized in large substations to identify a specific breaker that can be interchanged IN THAT SUBSTATION with other “E” breakers.  Once the breaker is being resold the “E” designation is not important for determining interchangeability.

* AKJ:  Indicates a replacement AKR-50 that will fit in cubicle originally equipped for AK-50

* AKS:  Indicates a replacement AKR-50 that will fit in cubicle originally equipped for AK-50

Here is the chart that I promised that puts all of this together:

AKR

<1>

-

<2>

<3>

-

<4>

<5>

-

<6>

The numbers above refer to all of the different styles that I spoke about in this article

<1> - Indicates whether the breaker is anything but a standard AK.

·         AKRU: Fused breaker

·         AKRT: Designates that it is a 2000A frame AK-50

·         AKRL: AKR breaker designed to replace AL-2-50 breaker

<2> - Indicates what trip unit was originally installed on the breaker

·         AKR-2: EC trip unit  - typically ONLY  on DC breakers

·         AKR-4: ECS solid state trip unit

·         AKR-5: SST solid state trip unit

·         AKR-6: Versatrip solid state trip unit

·         AKR-7: MicroVersaTrip RMS-9 solid state trip unit

·         AKR-8: MicroVersaTrip EPIC trip unit (designed to use with the EPIC monitoring system)

·         AKR-9: MicroVersaTrip PLUS or PM solid state trip unit

·         AKR-10: MicroVersaTrip PLUS or PM solid state trip unit

<3> Refers to the type of switchgear the breaker is designed for.

• A:  AKD-6 switchgear
• D: AKD-8 switchgear
• B:  Indicates Non-OEM breaker, AKR-30 and AKR-50 only.  Could rack into AKD-6 or AKD-8.  Caution should be taken to inspect escutcheon and finger clusters when interchanging. 
• C:  Indicates Non-OEM breaker, AKR-75 and AKR-100 only.  Typically for AKD-6 gear although it is important to note that AKR-5C-100 breakers will not replace AKR-5A-100 breakers due to differences in width.
• F: Indicates Non-OEM breaker, AKR-75 and AKR-100 only.   Typically utilized in AKD-8 gear but caution should always be used in interchanging.

<4>  Refers to the frame size and interrupting capacity of the breaker

·         30:  800A frame size, 30,000 Amp interrupt capacity at 480VAC

·         50:  1600A frame size, 50,000 Amp interrupt capacity at 480VAC

·         75:  3200A frame size, 65,000 Amp interrupt capacity at 480VAC

·         100:  4200A frame size, 85,000 Amp interrupt capacity at 480VAC

·         125:  5000A frame size, 100,000 Amp interrupt capacity at 480VAC

<5>  Refers to special features of breaker

• H:  Indicates High Interrupt Breaker
• AKR-30H:  42,000 amp interrupt at 480VAC
• AKR-50H:  65,000 amp interrupt at 480VAC
• AKR-75H;  85,000 amp interrupt at 480VAC
• L:  Indicates extra high interrupt AKR-30,  AKR-30L is 65,000 amp interrupt at 480VAC
• E:  Indicates high interrupt 4000A frame, AKR-7D-100E is 200,000 amp interrupt at 480VAC

Note:  This article is intended to assist in identifying AKR circuit breakers.  It should not be used as an absolute guide as it is possible to have any number of modifications that could result in misleading nameplate information.  Please call 1-800-909-3660, email sales@naswgr.com or visit www.naswgr.com for more information about General Electric AKR circuit breakers.

General Electric AK Circuit Breaker

I can’t count how many times North American Switchgear receives a call for an AK-25 breaker.  Now, believe me, I am grateful for every single sales call we receive but usually when that call comes in for the AK-25 breaker, there is a period of frustration on the part of the customer and the salesperson in retrieving all of the other information needed to provide the correct breaker.  Here is all of the information you will need (and probably some you won’t need) in order to make sure you have all of the knowledge you need to request almost any General Electric AK circuit breaker.  Newer style AKR breakers will be addressed in a different article.

This gets wordy … so there is a chart to sum it all up at the end.

AK breaker nomenclature is divided into three (and sometimes four) parts.   The parts are separated by dashes on the nameplate.  For example:

AK  -  3A  -  75  - 2

The first part tells you it is a basic AK breaker.  Also, if the breaker is ‘special’ there will be an extra letter tacked on to the AK.  The second part tells you the type of trip unit the breaker was manufactured with and also what type of switchgear the breaker racks in to.  The third part tells you the interrupting capacity of the breaker and also the frame rating of the breaker.  The fourth part indicates vintages of the specific breaker type that the first 3 parts refer to.  These individual parts are described in more detail below:

The Second Part - Type of Trip Unit and Type of Switchgear:

What is the difference between an AK-2-25 and an AK-6-25?

What does that number in the middle of the breaker type mean?  It refers specifically to the trip unit that the breaker was originally supplied with.  AK-1 and AK-2 breakers (yes, including “AK-2A”) were originally manufactured with old style, theremal magnetic EC trip units.  There were a variety of EC trip units manufactured such as EC-1, EC-2, EC-2A etc.  Each style involved engineering changes, different time curves and trip functions.  As solid state technology evolved, General Electric began manufacturing different solid state trip devices.  Each new solid state device was represented as a new number in the middle of the breaker model type.  For example, AK-3 breakers had Power Sensor trip units, AK-4 breakers utilized SST, AK-5 breakers utilized ECS, AK-6 utilized Versatrip, AK-6 utilized Versatrip and so on and so forth.  You can see all of the trip types in the table at the end of this article. 

AKD Switchgear

AK breakers were manufactured starting back in the 1950’s and later vintages of AK breakers are still manufactured today.  The earliest AK breakers were nameplated as “AK-1“.  The early model AK breakers included the  AK-1-15, AK-1-25, AK-1-50, AK-1-75 and AK-1-100.  In the 1960’s GE moved to the “AK-2” breaker including AK-2-15, AK-2-25, AK-2-50, AK-2-75 and AK-2-100.  In general (and I say this loosely) AK-2 breakers will replace AK-1 breakers with similar ratings and features.  General Electric termed the switchgear for their AK-1 and AK-2 breakers as type AKD.  One notable characteristic of AKD switchgear and breakers is that the racking hardware to insert and withdraw the breaker from the cubicle is located on the breaker itself. AKD style breakers are typically characterized as having a large rack-in handle on the right hand side of the frame.  Earliest vintage AK-1-15 and AK-1-25 breakers have a “U” shaped handle that runs across the front of the breaker that is used for racking the breaker into it’s enclosure.

AKD-5 Switchgear

Starting in the mid-1960’s General Electric modified their switchgear and breaker design.  The defining characteristic of the updated design was to move the rack in hardware to the enclosure itself which eliminates the handle on the right hand side of the breaker.  AKD-5 switchgear is characterized as having the letter “A” in the center of the model number.  The first AKD-5 breakers included AK-2A-15, AK-2A-25, AK-2A-50, AK-2A-75 and AK-2A-100. 

The Third Part - Interrupting Capacity and Frame Rating of the Breaker:

What does the “25“ refer to in AK-2A-25?

You really can get a lot of information from an AK model number.  The third group of numbers in the AK model type refers to the interrupting capacity  (in kiloampere) of the breaker at 480VAC.  For example and AK-2-50 breaker will interrupt up to 50KA or 50,000 Amps at 480Volt.   Conveniently, this number also correlates directly with the frame ampere rating of the breaker.  AK-50 breakers all have 1600 amp frames, AK-25 breakers all have 600 amp frames, AK-100 breakers all have 4000A frames.  You can see this correlation in the chart at the end of this article.

The Fourth Part - vintage of each individual model type:

What does the “-2” mean at the end of my AK-3A-50-2?

Finally, a number you don’t need to worry much about.  The very last number - when present - doesn’t mean much at all.  On later model AK breakers it represents minor engineering changes.  On earlier AK-1-25 and AK-1-15 breakers that final number can often tell you if the breaker is full frame or half frame. 

Exceptions to every rule - An important part of this article!!

As with anything involving power circuit breakers, nothing is absolute.  General Electric made lots of different breakers with specifications that bend the rules that I’ve stated so far.  Luckily, they did a great job of indicating this with changes to the model nomenclature.  These modifications include:

            AKU breakers:  The U in AKU indicates that you are working with a fused system.  For AK-15, AK-25 and AK-50 breakers this means that the breaker itself has current limiting fuses integrated into the frame of the withdrawable breaker.   Because of the addition of the fuses, the interrupting capacity of AKU breakers is typically increased to 200,000 Amp (200KA).  AKU breakers were manufactured for both AKD and AKD-5 switchgear so the full model number for an AKU breaker would be AKU-2A-25, AKU-2-25, AKU-2-50 etc.   If the frame rating is higher than 1600A, the fuses are integrated to a separate withdrawable element that racks into a similar envelope to the breaker itself.  For example, an AKU-2-75 would require two different withdrawable elements to operate properly.  First, the AK-2-75 breaker and second the 3200A fuse truck. 

            AKT breakers:  Remember when I said AK-50 breakers have 1600 Amp frames?  They do - except when they are labeled as AKT-50 breakers.  The “T” increases the frame rating to 2000 amp.  AKT breakers came for both AKD and AKD-5 switchgear (I.e. available as AKT-2-50 and AKT-2A-50). 

            High Interrupting Breakers:  Remember when I said that an AK-50 breaker interrupted at 50KA at 480VAC?  They do, except when the model number is designated with an “H” at the end.  The “H” refers to the breaker having the capacity to interrupt at 65KA at 480VAC.  “H” breakers can be AK-2-50H or AK-2A-50H.

            Stationary Breakers:  Remember when I said that AK breakers racked into different types of switchgear depending on the vintage in which they were manufactured?  Well they do - except for when they are stationary.  Stationary breakers do not have any specific nameplate designation to identify they as stationary.  I personally have never seen an original AK-2A stationary breaker, they are normally nameplated as AK-2 or AK-1. 

            Non OEM Breakers:  Occasionally we will get a call for an AK-2-25, electrically operated, drawout, new trip unit… seems simple.  It is simple until we find out that the customer’s switchgear was manufactured by NELSON SWITCHGEAR and not by General Electric.  Big big difference!!  This is something that is very important to keep in mind because several switchgear builders such as Nelson utilized GE type AK breakers for their projects.  They often purchased stationary breakers from General Electric and outfitted them with their own racking hardware and secondary disconnects.  An AK-2-25 breaker that was modified for Nelson switchgear will NOT fit into standard AKD gear!  Luckily, this doesn’t happen too often.

Here is the chart that I promised that puts all of this together:

AK

<1>

-

<2>

<3>

-

<4>

<5>

-

<6>

The numbers above refer to all of the different styles that I spoke about in this article.

<1> - Indicates whether the breaker is anything but a standard AK.  

• AKU:  Fused breaker
• AKT:  Designates that it is a 2000A frame AK-50
• AKR:  New style design – discussed in a different article

<2> - Indicates what trip unit was originally installed on the breaker

•  AK-1:  EC trip unit
•  AK-2:  EC trip unit
•  AK-3:  Power Sensor (GE’s first solid state trip unit)
•  AK-4:  ECS solid state trip unit
•  AK-5:  SST solid state trip unit
•  AK-6:  Versatrip solid state trip unit
•  AK-7:  MicroVersaTrip RMS-9 solid state trip unit
•  AK-8:  MicroVersaTrip EPIC trip unit (designed to use with the EPIC monitoring system)
•  AK-9:  MicroVersaTrip PLUS or PM solid state trip unit
•  AK-10:  MicroVersaTrip PLUS or PM solid state trip unit

           

<3> - Indicates what type of switchgear the breaker is designed for

• If BLANK (no letter):  Indicates type AKD switchgear
• If “A”: Indicates AKD-5 switchgear

<4> - Indicates interrupting rating and frame size of breaker

• “15”:  Indicates 225A frame, 15000A interrupt at 480VAC
• “25”:  Indicates 600A frame, 25000A interrupt at 480VAC
• “50”:  Indicates 1600A frame, 50000A interrupt at 480VAC
• “75”:  Indicates 3000A frame, 75000A interrupt at 480VAC
• “100”:  Indicates 4000A frame, 100000A interrupt at 480VAC

<5>- Indicates additional special features of the breaker

• “S”: Indicates breaker is equipped with a Quick Close relay
• “H”: Indicates breaker is built to interrupt above its frame rating (i.e. an AK-2-50H may interrupt current as high as 65,000Amp)
• “X”:  Indicates that the breaker is special.  We have seen “X” breakers that were DC and also X breakers with unique physical frame sizes for their rating

<6>- Indicates typically minor engineering changes throughout each individual vintage.  The most notable change is in the AK-1 vintage where earlier models had a full box frame style and later models had what is referred to as a half-frame style.             

A couple examples to utilize the above chart:

AKT-2A-50:  This would be a 2000A frame AK-50 breaker that has an EC series trip unit that is designed to rack into type AKD-5 switchgear.

Or

AKU-3-25:  This would be a standard 600A frame AK breaker equipped with current limiting fuses, Power Sensor trip unit and designed to rack into type AKD switchgear.

Keeping out of trouble:

This article was written primarily to identify the nomenclature of the AK model number.  Even with all of this knowledge, we will still need more information in order to accurately provide a customer with an AK circuit breaker that matches their system.  Is the breaker electrically operated or manually operated?  If it is electrically operated, what is the voltage of the close coil (or charging motor depending on mech type), control relay and trip coil?  What type of trip unit do you actually need?  VERY often, AK-2 and AK-2A breakers have a more modern solid state kit retrofitted onto them.  What trip function is required on your solid state kit?  For fused breakers, what size fuses are required?  Does your breaker have any special auxiliary devices such as bell alarm or UV (under voltage) device?  Lots of questions.  Sometimes the best way to find answers is to take photographs of the nameplate AND of the breaker itself (front and back if at all possible).  Most of the time, with photographs, our sales people can identify the breaker type, specifications, trip unit and auxiliary devices.

Note:  This article is intended to assist in identifying AK circuit breakers.  It should not be used as an absolute guide as it is possible to have any number of modifications that could result in misleading nameplate information.  Please call 1-800-909-3660, email sales@naswgr.com or visit www.naswgr.com for more information about General Electric AK circuit breakers.

Welcome To Our Blog

Welcome to my breaker blog!  My name is Kristen Habeeb and I am the sales manager and VP of North American Switchgear, Inc. in Cleveland, Ohio.  We’ve been selling power circuit breakers, switchgear and replacement parts for the past 31 years.  Our company was started by my father, Bob Jordan back in 1980.  We currently have over 7000 large power circuit breakers in stock rated between 480VAC and 15kV.  We also have hundreds of sections of low and medium voltage switchgear, load break switches and thousands of replacement parts.  We have a full time rebuild shop constantly involved in reconditioning, testing and repairing low and medium voltage breakers and also retrofitting low voltage power circuit breakers.  Similarly, we also work with low and medium voltage motor control.

I have been involved in the sales department at North American Switchgear since 1999 when I graduated from Case Western Reserve University in Cleveland.  We are proud affiliate members of NETA and full members of the Professional Electrical Apparatus Recyclers League.  I served on the board of directors for this organization for five years including a term as President of the organization.  My husband Michael works with our company and we have three beautiful daughters.

So, why start a blog about circuit breakers?  I’ve been thinking about putting this together for a long time in response to commonly asked questions and concerns from customers.  I hope to address subjects such as breaker nomenclature, interchangeability, maintenance, common problems and solutions.  If you have questions or specific topics you would be interested in please don’t hesitate to contact me!  I can be reached by e-mail at kristen@naswgr.com or by phone at 800-909-3660.  I certainly look forward to any feedback that is received.