Blog posts tagged with 'MagneBlast'

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.