UEA Tech Talk

Slip Rings in Off-Shore Wind Turbines

Slip Rings in Off-Shore Wind Turbines

Standard wind turbines have proven to be a harsh and rugged environment for electrical slip rings.  However designing slip rings for off-shore wind turbines is an even tougher challenge.  Not only are we dealing with gearbox oil, dirt and vibrations, but now we are aslo exposed to salt water and salt air.

The salt environment can cause a few different problems for a slip ring if not properly designed.  First of all, the outer housing and hardware must be suited for slat air. Even if a rusty enclosure and screws don’t change the performance of the slip ring, no turbine manufacture wants to install a rusty component on a multimillion dollar machine.  United Equipment Accessories uses all stainless steel hardware if possible which also makes maintenance much easier.  As for the housing, aluminum is generally used among all slip ring suppliers as it is durable and light weight, but it's not the most corrosion resistant material.  Because of this, UEA has standardized to have aluminum components anodized if being used in a salt air environment.

No matter how well a slip ring enclosure is sealed it seems the salt air still finds it way inside.  This can cause brass rings to corrode at a much more accelerated rate.   The biggest challenge is to keep the rings from starting to corrode before they are put to use.  A lot of the slip rings will sit for months before they are actually being used.  If they are sitting in a salt environment, some type of protection is needed.   UEA uses a type of electrical protection spray that coats the rings and stops them from corroding, but the biggest benefit that UEA offers over most competitors is the self cleaning brushes.  We run a very high brush pressure compared to most manufactures, so if some corrosion on the ring does occur, the brushes will clean the rings as they begin to rotate.

These are just a couple of the issues that we take into consideration when designing slip rings for the off-shore environment.  As the wind industry progresses I have a feeling we will be seeing a lot more of these applications.

-Jesse Shearer, Design Engineer

Slip Rings -Slew Indication Part 2

 ...Continued from Blog: Slip Rings -Slew Indication Part 1

 A variety of encoders have also been used with UEA slip ring assemblies over the years but relatively new on the scene are encoders with a CANopen or J1939 output.  These are most frequently used, at this point, on mobile or construction equipment with similar needs to those supplied by the potentiometers.  Because they operate on a CAN communications system the encoder can become just another sensor on the system and its position above or below the center of rotation is immaterial once attached to the CANbus circuits passing through the slip ring.   As more engine controls and remote sensors adopt the CANopen or J1939 output the use of this type of encoder will become even more popular.

As always, United Equipment Accessories, Inc. is available to answer any questions you may have about our products, or this blog post.  Please feel free to contact us at 1-877-352-4739 or email at info@uea-inc.com. We promise that you will speak directly to an employee in our office, never an answering service!  Check out www.uea-inc.com for more helpful information about United Equipment Accessories Inc, and our products.  Hope to hear from you soon!

-Brent, Senior Design Engineer

 

Slip Rings- Slew Indication Part 1

An electric slip ring assembly is used to conduct electrical power and signals throughout a continuous 360 degree rotation.  In some applications it is also important to have some means of indicating areas or specific positions within the 360 degrees.   This can be done in a variety of ways depending upon the actual number of positions or areas required, whether they are permanently set or need to be programmable and upon the accuracy required.   For the simplest applications, such as a single ‘home’ position on a small crane, amusement ride or indexing table, UEA has for approximately 30 years incorporated a laser cut cam plate into the center core stack of rings and insulators in the slip rings.  As the slip ring rotates the roller on a spring-loaded arm follows the contours of the cam and actuates a small single-pole, double –throw switch.   An accuracy of plus or minus one degree is achievable and repeatable with this design with up to three areas defined over the 360 degree rotation with one cam.   Another cam can be added for additional defined areas but obviously adds additional height to the core stack.

     For more than 15 years UEA has offered the option of a continuous rotation potentiometer that supplies a unique signal for any point during the 360 degree rotation of the equipment to which it is attached.  Normally supplied with a slip ring assembly, the potentiometers provide an analog signal that is converted by customer supplied software, such as that used for a crane LMI (Load Moment Indicator) system, into a given position.  The LMI system uses the rotational position, along with boom angle, boom extension and the weight of the part being lifted to compare to the lift charts having already been determined for that crane.  Because the outriggers extended to support a crane during a lift operation are not normally square in pattern, a typical crane can lift more over the front and rear of the machine than over the sides and the lift charts reflect that variation.  The potentiometers are a vital part of the LMI safety system for lifting but they also provide another safety feature that is not available with the cam and switch system.  Using the potentiometer position signal, the crane boom can be swung to a position and a stop or set point established.  Another set point can then be established which will then limit the crane to movement between these two points.  This is particularly important if the crane is working close to buildings, power lines, etc.  By establishing swing limits the crane operator is automatically warned as the boom swings close to the danger points.  UEA has two potentiometer styles with one being a traditional 2.00” O.D. with shaft drive and the other being  4.00” O.D. with a 1.50” through bore for use with slip rings that need to pass pneumatic, hydraulic or other types of passages through the assembly.

The UEA Way!

UEA is always planning for future facility growth needs of our slip ring, cable reel and transmission shift control product lines.  The current economy has made building construction prices more attractive.  We started construction on an additional 4300 square feet of production area in June.  We are anticipating completion sometime in late August. 

Our south building addition will fully utilize the land area available for this plant.  The new building will actually attach to one of our current warehouses to facilitate cable reel inventory storage.  All future building expansion will be done at our north facility which has ample area for future growth.

This addition will allow our cable reel and shift controls departments to return to their old homes at the south plant.  We have completely reconfigured our slip ring production areas to more fully utilize lean manufacturing techniques and interdepartmental flow efficiencies.  All of the slip ring, cable reel, and transmission shift control departments will have gained 25% - 50% in potential capacity with the space reorganization and improved efficiencies. 

The areas at the north facility that the cable reel and transmission shift controls departments vacated will be utilized for up to three additional dedicated lean manufacturing lines for slip rings for wind generator clients.  We will always have the capacity to meet your slip ring, cable reel, and transmission shift controls needs.  Being proactive for our customers is the UEA way.

-Mark Hanawalt, President

Reflections of Progress (shift controls, cable carriers) Part 2

Our first CNC was a small, though it seemed large to us at the time, vertical machining center.  This machine could speed through drilling, tapping and milling operations much faster and more repeatable than could ever be imagined on the multiple drill presses that previously executed these functions.  The next addition was a pair of machines.  A larger vertical machining center and a CNC lathe with live tooling. The lathe changed the way we looked at many of our common operations.  This machine allowed us to complete secondary operations on a part without the need to transfer the part to another machine and we could do things that were not even possible with our previous equipment.  One operator + one machine + one handling of the part + multiple operations = higher efficiency and better throughput.  We later added another similar lathe to increase capacity.

 Two CNC Live Tooling Lathes

The next major update came with the addition of a horizontal machining center with an automatic pallet changer.  This piece of equipment became a necessity due to our entry into the wind turbine slip ring market. The ability to be loading one pallet with parts while the other pallet is being machined keeps the productivity of the cutting tool at its highest possible level.  This machine also added the capability to machine on three sides of the part in one clamping.  This has eliminated having to clamp parts in four different positions to complete all operations. It is now done with two positions and with much higher accuracy than before.

 

Horizontal Machining Center with Automatic Pallet Changer

 

 Automatic Pallet Changer Loading Station

 

Our latest addition is a dual spindle dual turret live tool lathe.  This new piece is basically two lathes built in one cabinet end to end such that one spindle can actually move over and grab a partially finished part from the other spindle to do work on the back side.  This allows the machine to be cutting on two parts simultaneously.  In effect, two machines in one footprint.  Due to our rapidly filling floor space, this is a serious consideration at present.

 

With the advances that I have witnessed in the last 2 decades, I can’t wait to see what the next decade will bring.

Kent Davis

Design Engineer

Reflections of Progress(slip rings, cable reels)Part 1

Throughout the 20+ years that I have been employed at United Equipment Accessories I have seen some things change substantially, and have seen other things that continue to remain the same.

In the realm of the manufacture of electrical slip rings, cable reels and shift controls, the basic principal of creating  sound, reliable and durable products that consistently outperform the competition has remained the top priority at United Equipment Accessories.  Meanwhile, the processes and equipment used to achieve this end goal has evolved dramatically.  The production of electrical slip rings at UEA involves several operations that tend to be specialized.  In the past these operations were sometimes completed with the combination of workers with special skill sets or custom built equipment, or a combination of the two.  Over the years I have been involved the design and building of several of these specialized machines.  As technology has advanced in the marketplace of CNC (computerized numerical controlled) machinery, several of these specialized or “purpose built” machines have been replaced by more standardized CNC machines that can perform the functions of the old machines as well as in some cases also perform additional “bonus” functions, and do it all in equal or less time than was required by the specialized equipment.  It can be a little bit of a mixed emotion to see one of these old machines that was designed and built in house and worked so well in the past be pushed to the store room or scrapped when a new CNC machine arrives.  But this is overcome when you see the new capabilities being utilized to do operations and make parts in ways that weren’t possible just a few short years before. (Con't...)

Slip rings and Cable Reels

United Equipment Accessories manufactures slip rings for a number of different and diverse industries from utility grade turbines to anti-two block reels (for both the service and maintenance and vacuum pumper truck industries). What has impressed me is the variety of different slip ring applications for which UEA can manufacture. We offer electrical cable reels with our slip rings in place. We design, develop and manufacture rings to our client’s exact specifications within four weeks not months as I have seen from other manufacturers. UEA engineering listens to our customer’s particular needs and designs a ring to not only meet but exceed those requirements. I am proud to say that UEA manufactures for a number of premier utility grade turbine OEMs. The list of crane companies for which we manufacturer is second to none. As the UEA mission statement states, “UEA provides innovative solutions for our customers specific motion application needs” and “to succeed where others have failed.”

 United Equipment Accessories is striving to be the leading manufacturer of quality custom components for motion applications, Worldwide. Our customer satisfaction is beyond reproach. The UEA engineering and support staff is always available to answer questions on the four products that UEA offers, which means that you can actually talk to someone.

United Equipment Accessories offers a test and loan prototype slip ring built to each client’s exact specifications for actual field testing in various harsh and demanding environments. This offer has been an excellent selling tool when speaking with both the engineering and purchasing managers we meet with, this is just one key point that differentiates UEA from our competition.

   The UEA slip ring is a component that once in place speaks for itself in it performance, offering 50 -75 million revelations before the brushes need to be replaced. UEA is working on bettering the life expectancy so that the UEA slip ring will still be there when others have failed.

 You will not go wrong in choosing to install our slip rings in your machines.

-Jim Carnegie, National Sales Director

Hybrid Slip Rings

There are many challenges slip ring manufacturers face in dealing with harsh environments and rugged applications, but data circuits seem to be a common issue.

UEA has recently partnered with PowerbyProxi who has developed an advanced contactless/wireless slip ring technology.   This has allowed UEA to manufacture what we are calling "Hybrid Slip Rings".  This is a combination of a traditional UEA slip ring along with the contactless slip ring technology. 

Currently our wireless slip ring design is capable of handling 750watts of power along with Ethernet or CANbus.  However, some of our applications require high power circuits that cannot be done with the wireless technology.  With our hybrid slip rings we are able to meet the high power needs along with the most reliable data circuits available, all within one package.  

For example, in the wind turbine market the data circuits are troublesome because of the harsh environment.  Vibrations, leaking oil and extreme cold temperatures are all present in wind turbines and can all affect the resistance of a slip ring circuit.  With the new hybrid slip ring UEA is able to handle the high power circuits with conventional rings and brushes, which we do without any issues; and in the same package use the contactless technology for the low power and data circuits to completely remove the possibility of the of them being affected by the environment.   

UEA has came up with a solution that has removed one of the few troublesome areas of the slip ring and moved closer to create the perfect slip ring. This is simply one example as new technologies arise UEA has devoted itself to staying "ahead of the game" as a slip ring manufacturer.

Jesse Shearer -Design Engineer

UEA Slip Ring Assemblies

 

The fact that UEA slip ring assemblies are known for their dependable service in a wide variety of environments stems from their original design to operate in the rugged and dirty world of construction equipment.  The first UEA slip rings were designed and built when UEA founder, Vern Iserman, was unable to locate or purchase a slip ring design that would stand up to the environments encountered by the electro-pneumatic remote control packages he was building and installing on small truck mounted cranes and draglines for the Shield Bantam Co.  The patented brush assembly design included two brush contacts, each radiused to match the OD of the ring contact, with paralleling insulated brush shunt between the contacts.   The contacts are each riveted to an insulating brush arm with the contact allowed to pivot around the rivet.  The brush arms are stacked over a stainless steel stud, with the arms also allowed to pivot on the stud, and the two arms in each pair tied to each other with an extension spring.  This design with three pivot points, including the brush contacts and the brush retention post, allows the UEA brush to maintain contact even with a considerable amount of misalignment or oscillation as the equipment and bearings wear.  The brush design, with the spring insulated from the actual circuit, precludes the possibility of the spring losing tension due to overheating, etc. when the spring serves dual-duty as both the brush arm and conductor as used on many other slip ring brush designs.  Operating with the high contact force of 15-18 lbs./sq. in. the UEA brush contacts not only provide very good cleaning action to wipe the rings as the brushes rotate but a very high resistance to contact bounce as the equipment vibrates.  Another unanticipated advantage at the time of their design of the high contact pressure at the brush contact to ring interface is that the very low contact resistance permits the use of lower level signals such as video and audio even on some of the standard circuits with copper graphite contacts and brass rings. 

      Using variations of both contact and ring materials has allowed the basic double-contact UEA design from the 1960's to be used in a wide variety of applications and environments around the world nearly 50 years later.  Using that same basic brush design the UEA slip ring line has been expanded to meet through-bore slip ring needs from 0.50" to 14.00" in inside diameter.

Wireless Slip Ring at the Windpower!

 UEA just shipped the Windpower 2010 tradeshow gear down to Dallas!  It's a big relief once the booth items are organized, crated, and shipped off to the show.  We are very excited about the show this year as we will be introducing our newest product-the wireless slip ring!  There will be a special display just for the slip ring so don't forget to stop by and see how the new technology works.  It is truly amazing!  Of course we will also have our current products for wind turbines on display as well as the helpfulness of our engineers and sales staff to answer any questions you may have.

 See you all there at Booth #1926