The History of I.T.E. Low Voltage Circuit Breakers

I.T.E. has been an innovator in the area of low voltage power air circuit breakers since the dawn of the industrial use of electricity. The name I.T.E. in itself represents the origin of the modern, resettable circuit breaker. I.T.E. actually stands for Inverse Time Element. This is the heart of every overcurrent trip device. When a fault occurs, it causes the breaker to trip faster as the rise in current increases. In other words, the higher the current, the faster the trip, consequently they work inversely to each other.

The inverse time element was a major stepping stone in the commercial use of electricity. Not only was it a cost-effective alternative to replacing costly fuses, as it was developed it became adjustable for various applications and became an integral part of industrial and commercial safety programs. The element had been used for years by the original Cutter Electrical Manufacturing Company and later the Walker Switchboard Company and had become so synonymous with their products that in 1928 the name was changed to I.T.E. Along the way, as I.T.E. continued to develop, it merged or was acquired by other companies and changed names from I.T.E., to I.T.E. Imperial, then later to BBC for the Brown Boveri Corporation and later when merged with Asea to ABB for Asea Brown Boveri.

The inverse time element as the heart of the series overcurrent trip device is the heart of the first of many lines of air circuit breakers produced by ITE, curiously all of whose model numbers started with the letter “K”.

Slate Back Breakers

The first of these lines, commonly known as the “slate back” breaker, came totally enclosed in a metal frame with a handle on the exterior of the door to safely operate the enclosed air circuit breaker. The breaker line could either be produced with breakers bolted to the line and load side buss or equipped as “draw out elements” that once opened could be safely removed from the cubicles without need for a buss, and major production, shut down. The product line was broken into specific frame sizes equipped with trip devices ranging up to the maximum amperage capability of each design:

  • KA - 225 amp frame
  • KB - 600 amp frame
  • KC - 800, 1200 or 1600 amp frame
  • LX and LG 1600 amp through 8000 amp frames 

Steel Back Breakers

These breakers have been used extensively through the World War II era in both civil production and military applications. After the war, the “slate back” line was replaced with the “steel back” product line. These ITE circuit breakers feature individual insulated pole pieces mounted to a steel frame that is also housed within a steel cabinet and are operated with the individual doors closed for safety. Each breaker contains an individual series overcurrent trip, designated by either OD-1 or OD-2. The OD-1 has adjustable time band settings for both a long delay for moderate overloads or instantaneous for protection of more massive overloads. The OD-2 has time bands for both long-time and short-time bands and has found a use for protection of electric motors and their initial inrush of current on startup. The model numbers of this production line resemble the previous line in many ways.

  • KA - 225 amp frame
  • KB - 600 amp frame
  • KC - 800 and 1600 amp frame
  • KD-A  - 3000 amp frame
  • KE-A - 4000 amp frame

Even though the two production lines have similar model numbers and they have some parts that are interchangeable, the breakers themselves are NOT interchangeable between lines. This requires operators and maintenance personnel to be familiar with these differences when ordering ITE replacement breakers and parts for their switchgear. The personnel at NPE have developed a variety of ways to recognize these vintage changes to help guide customers to identify what they need. Among the questions that you may be asked when looking for these breakers is: What is the serial number? It turns out that the slate back product line has 4 to 5-digit numerical serial numbers and the steel back line all have a letter prefix (A through G) preceding these numbers. Depending on your requirements, internal parts changed even within the letter designations of these steel backs.

K-Line Series Breakers

The next major change in the product lines was the official “K-Line” series of breakers. The primary change from previous versions was the downsizing of the overall frame size to conserve space. A spring charged mechanism provided for faster closing and opening and reduced arcing and the “closed door draw out” design that not only allowed the breaker to be operated with the door closed but also “racked out” (disconnected) from the line and load side buss with the door closed for operator safety. This first generation of K-Line breakers became known as K-Line Black, because of the black plastic used as insulation on the poles and arc chutes.

  • K-225     225 amp max
  • K-600     600 amp 
  • K-1600   1600 amp

Large frame requirements still rely on the older KD-A and KE-A frames for mains and ties.

The product line continued to improve with options. For instance, an option for both fused and series overcurrent protection was offered in the K-DON series, designated as K-DON 600, K-DON 1600. The series fuses provided extra protection from massive faults and increased the ratings of the breakers to 200,000 AIC.

These breakers continued to evolve from the original breakers with black plastic moldings to a more compact version with red moldings. There was some interchangeability between some of these product lines, but it is limited. K-225, K-600 breakers enjoy some interchangeability, the K-1600 has a one-way interchangeability and the addition of K-3000 and K-4000 amp mains and ties replaced the KD-A and KE-A breakers. The K-DON series has some parts interchangeability but are not interchangeable as complete units.

Later improvements emerged with the introduction of the first solid-state overcurrent trip devices which offered more reliable time curves, more flexibility with trip ratings and better overall performance. These changes are designated with either a “S” or “M” suffix on the model number, for example, “K-600 S” for first peak sensing solid state trips or “K-600 M” for the first RMS sensing overcurrent trips.

Although many, if not most of these products have been out of production for years, they remain in service in various applications throughout the country today. While some technical details are limited and the models are easily confused, used equipment dealers like National Power Equipment have the experience and expertise to help guide you through the variations and provide you with quality parts to maintain your equipment and keep production going. In many cases, NPE is the only viable candidate for new parts for these ITE breakers with their ever-growing aftermarket product group. Click on this link to view these parts: ABB/BBC/ITE Aftermarket Parts List

Contact us and let NPE supply you with The Right Part, at the Right Price, Right Now!

NPE...Your "Electrical 911"

Hurricanes, floods, lightning strikes or just a simple tree falling on a transmission line can trigger a catastrophe that shuts down power. Without power, there is no production and the cost of downtime can cost tens of thousands of dollars – per hour.

Electricity drives production in the modern world, and often times production is run on switchgear and circuit breakers that have been out of production for years, if not decades. If you call the original manufacturer and they tell you they no longer support your product line, their only option will be to replace your equipment with whatever they are currently producing. This will often entail reconfiguring your distribution system, paying big bills and waiting months for “the latest and greatest” product line only to find out that it’s less reliable than what you previously had and within a short amount of time will be obsolete as well.

So, when disaster strikes and you’re faced with these obstacles, what do you do, who do you call to restore production in the fastest and most economical way? That’s what National Power Equipment is here for. As a stocking distributor of used, remanufactured circuit breakers and switchgear, parts and our ever-growing list of aftermarket parts, NPE can supply you with the right equipment, at the right price and most importantly, right now! Our warehouses are stocked with low voltage (600 VAC or less) through medium voltage (15,000 volts or less) air and vacuum circuit breakers, switchgear, medium voltage motor starters, load break switches, and all of the parts needed to go with it. Our inventory not only contains equipment that dates from the World War II era to current, but our staff has the experience, knowledge, and expertise to get you up and running in hours, days or weeks instead of months. Think of us as your “ELECTRICAL 911”. When disaster strikes, large or small, we can assess the problem, offer a variety of solutions and start implementing them right away.

For example, consider the case of a once in a 100 years flood that incapacitated a technical center for a major automotive company. While the water was still receding NPE was on site consulting with the contractor, assessing the damage and formulating plans. Parts and equipment began arriving the next day. NPE supplied medium voltage fuses and switch parts, low and medium voltage circuit breakers, relays and tons of parts, literally anything that was needed to get over twenty load centers back online.  The first of the substations came on in a week and within eight weeks 99% of production was restored.  Overall, NPE made seventy-nine separate shipments including one of sixty-seven circuit breakers that were reconditioned and ready to go.

Unexpected outages, large or small, require two things to overcome them – experience and options. Contact us we have both.

Replacement Labels for Your Rebuilds

Are you rebuilding your equipment? Let NPE supply you with new replacement labels to bring them back to “like new” condition. NPE replaces worn labels with new labels when doing our Class One” reconditioning procedure.

We have a database full of common labels that are available with same day shipping. If we do not have the particular label you need, no problem, in most cases we can design your label from scratch. Just provide us with a picture and dimensions.

It is important to communicate with safety labels the electrical hazards like voltage and shock hazards. We have some of these common warning/danger labels and we can also customize these labels for your specific needs.

We offer our labels on both silver and white adhesive paper which are then laminated for extra durability. No minimum quantity required. Contact us online, give us a call or send us an email for a quote!





How to Identify Raise Lower Mechanisms for Circuit Breakers and What You Need to Maintain Them

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.

Image of a cast raise lowe mechanism for a GE Magne-Blast circuit breaker.Image of a fabricated raise lowe mechanism for a GE Magne-Blast circuit breaker.

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!

Extend the Life and Reliability of Your GE Magne-Blast Switchgear with NPE’s Bottle Repotting Program

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.
  1.      Remove the outdated “tar pitch” potting right down to the filler. 

  1.      Re-align the connecting tulip and lock it in place so it doesn’t move and cause future failures.
  1.      Secure the joint between the copper and seal.
  1.      Insulate the buss with modern shrink tube insulation.
  1.      Replace the old potting material with a new two-part system that is thermally stable which will last far into the future.
  1.      Clean and silver plate all mating surfaces to increase conductivity at critical joints.
  1.      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 typically 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.