Collector ring maintenance and manufacturing from Cutsforth Products, Inc.

37837 Rock Haven Road
Cohasset, MN 55721
Phone: (800) 290-6458
Fax: (800) 398-6530
Email: sales@cutsforth.com
  Friday November 21, 2008   
 
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EASYchange Cartridge Brush Holder open and disconnected
EASYchange - REMOVABLE BRUSH
HOLDER SYSTEM



EASYchange Brush Holder being attached and closed.

After years of "TRUING" hundreds of turbine generator field rings, we have come to the realization that nearly all collector ring problems are holder related. The EASYchange removable brush holder was developed to:

  1. Improve conditions for maintenance personnel, and
  2. Combat ring damage including excessive ring wear, rings going out of round, and photographing (the latter two can cause failure sufficient to bring on a forced outage).

Besides reducing the chance of a forced outage, the EASYchange Brush Holder System can extend the life of the ring, reducing related scheduled outage time.

With the EASYchange Brush Holder System you can now completely maintain brush holders while the generator is producing power.

You can download a video demonstrating the ease of using the EASYchange Brush Holder System (730 KBS).

(Self-extracting zip file - Double click on the file after downloading to extract. Video is saved to a folder named EasyChange by default - double click on the easy_change.wmv file to run in Windows Media Player).

Pictures below show a GE Alterex converted
to the EASYchange Brush Holder System.
Here the EASYchange Brush Holder System is installed on a GE Alterex. It is manufactured out of stainless steel which is a great plus for generators operating in ocean side areas. It is locked in position by an over center action similar to a vise grip pliers. As the EASYchange Brush Holder is pulled, a safety catch is released, allowing the over-center lock to open. When the handle is rotated back completely, the holder can be pulled straight out. When installing the EASYchange Brush Holder you first align the two internal pins with the slots on the sides of the mount. Once the pins are in the slots, the holder will automatically track the rest of the way into position.

Click images for larger versions and descriptions

To make changing brushes easier, the EASYchange Removable Brush Holder System was designed with an insulated, ergonomic handle to easily "rack out" and remove the holder. As the handle is pulled and rotated to its retracted position, the terminal is disconnected from the fixed mount while remaining attached to the removable holder. In addition, the brush is retained in the brush box by a catch that is released only when the holder is positioned in a mount or in the changing station. This allows for hands-free control of the brush and brush shunt. Another advantage is the reduction of personnel's exposure to heat and fatigue because of the quickness and ease of removing the holder. You now have the freedom to change the brush, or perform any other brush holder maintenance away from the generator.

The EASYchange Online, Removable Brush Holder System has dealt with the three (3) main contributors to rings going out of round, photographing or wearing excessively:

1) Brush Box Obstructions and/or Restrictions
a. Carbon Deposits - These are small amounts of material, that adhere to the inside of the brush box and hinder free movement of the brush. This keeps the brush from making good contact with the ring, which will electrically erode the ring's surface. The EASYchange Brush Holder, because it is removable, can be inspected and, if necessary, cleaned at any time.
This shows carbon deposits in a turbine generator brush holder. Carbon deposits are the number one reason rings go out of round. The carbon deposits in this photo extend the length of the holder. Because of these deposits the ring went from near perfect condition to having excessive brush vibration in less than one year. Here there are carbon deposits at the bottom edge of the boxes of this magazine holder. Although the holder box is accessible while the unit is running, we have found the deposits seldom get removed.

Click images for larger versions and descriptions
This shows erosion of the inside of the holder box caused by current being conducted through the box.  This picture shows erosion of the brush from current passing between the brush box and the brush. It also shows the effect of side pressure on a brush from the constant force spring when the brush is longer than the holder.
Click images for larger versions
b. Brush Box Erosion - Current passing between the brush and the brush holder can electrically erode the brush box, resulting in a very rough surface. This can restrict brush movement. The EASYchange holder is insulated so current only passes through the brush shunt and terminal, eliminating this possibility.
c. Brush Binding - Some brush boxes are shorter than the brush they hold. This can cause binding as the newer constant force springs exert side pressure as well as downward pressure on the brush.
This picture illustrates the damage that can occur to the brush from the brush binding in the holder.
Click for larger version
In some cases, this binding scenario can even cause a ledge to be formed in the brush that will eventually completely stop the brush from moving. The EASYchange holder has a box that is the same height as the brush, eliminating the possibility of binding.
2) Poor Springs
a. Worn Springs - Brush springs will eventually lose some of their tension and if they are not changed, will lead to excessive brush and ring wear. The EASYchange holder is designed with a QUICKchange spring that comes with every brush. This assures continual proper spring tension and yet does not increase the cost over properly maintained "spring clip" style springs.
b. Damaged Springs - Springs frequently become damaged. The EASYchange holder is designed to keep this from happening, but even if a spring is damaged, a new one comes with every brush and is easily changed.
c. Broken Springs - It is possible for this to occur over time. Here again, a new spring supplied with every brush solves the problem.
The kink in this spring developed after being in service for a time because friction increases between the two layers, restricting the springs from sliding within each other. If the brushes are snapped in the holder, the inner spring will kink. This picture shows the result of the kinked spring pressing into the side of the brush. This can restrict the movement of the brush and cause the ring to go out of round or cause photographing of the ring. Each brush is supplied with a new spring, which is no more expensive than replacing a traditional spring clip every ten years. The brush has a wear band on the shunt and sleeving above the wear band to help protect from making contact with an energized brush lead.

Click images for larger versions and descriptions
3) Poor Terminal Connections
a. Worn or Fatigued Quick Disconnect Connections - Common quick disconnects in the industry have the spring portion of the quick disconnect which supplies the contact pressure permanently mounted. This pressure can be lost over time, if the quick disconnect mount is not replaced, resulting in poor terminal connections. The EASYchange holder incorporates a brush terminal that itself is the contact pressure member. This means that the contact pressure spring portion is refreshed every time a brush is changed.

Some Sample Applications:

The EASYchange Holder is very compact and can be adapted to fit virtually any unit. These are just a few examples that demonstrate its versatility. An additional benefit of the design is that the mounts are permanently positioned relative to the ring surface. This means that any brush box can be placed in any mount while maintaining the correct clearance from the ring surface. Another convenience is that by adaptation of the EASYchange holder, brush sizes and types can be reduced to simplify inventory and ordering. Also shown in the following pictures is Cutsforth Products ability to design and produce revised brush riggings to adapt the EASYchange Cartridge Brush Holder if needed.

GE Three Gang Cartridge Holder
conversion
Westinghouse conversion with removable handle
Here is a picture of an original 3 gang holder on a GE generator.Here is the EASYchange conversion for the GE 3 gang holder. The first position shows the holder removed, and the mount exposed, the second shows the holder unlocked, and in the third position the holder is locked in position. This photo shows the EASYchange Brush Holder System and bolt-on 3 gang fixture mounted in a GE turbine generator. This is one of the very few applications where we can safely do a conversion while the generator is producing power. This photo shows the EASYchange Brush Hholder System conversion with a removable handle installed in a Westinghouse turbine generator.

Click images for larger versions and descriptions


EASYchange Holders and Yoke Conversion for an Allis Chalmers LP Generator. Brush size changed to 1.5" X 1" (Picture to far right shows original brush rigging)

This is an isometric line drawing of the EASYchange Brush Holder System and yoke conversion for an Allis Chalmers low pressure turbine generator. This is a solid model drawing of the EASYchange Brush Holder System and yoke conversion for an Allis Chalmers low pressure turbine generator. This picture shows the original yoke/holder in service on an Allis Chalmers low pressure turbine generator.

Click images for larger versions and descriptions



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