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”.

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
 

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 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 start up. 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 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.

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 breakers with their ever-growing aftermarket product group. Click on this link to view these parts: ABB/BBC/ITE Aftermarket Parts List

Give us a call, or send us an email and let NPE supply you with The Right Part, at the Right Price, Right Now!!