Tips & News - April 2012

Vol. 16 No. 2 | APRIL 2012 www. hubbe l l powe r s y s t ems . com ENDURING PRODUCTS AND PEOPLE YOU CAN DEPEND ON. TIPS NEWS

New foundation design revives collapsing 500kV towers see page 2 PILES: HELICAL

In this issue:

Seismically Enhanced Test Terminals ARVI Auto-Ranging Voltage Indicator Upgrading Surge Protection Anti-Corrosion Polymer Cutout Automation Ready Switch

Sectionalizing Cabinets Formed Wire Products

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HELICAL piles: New foundation design revives c o l l ap s i ng 500 kV t owe r s by Doug Hudspeth Front Line Manager Hydro One Networks Inc. Ontario, Canada

Late in 2008, an aerial patrol discovered three 500kV towers with partially- collapsed foundations on the power line between the Pinard Transformer Station and Porcupine Transformer Stationon theHydroOne system. Itwas a serious problem. The line transmits power from the Otter Rapids, Harmon and Kipling Generating Stations 100 miles down toTimmins.

30,000 km " of high-voltage transmission lines inOntario. Those towers are ‘V’ shaped, supported by a single pedestal foundation and four guy wires. The buried, pedestal foundations are constructed of lattice steel — four legs of angle irons that taper out as they extend down until they are 3 feet wide. From there they extend straight down an additional 5 feet. The angles are supported by diagonal members (flat bars and angle irons). The pedestal sits on top of a network of steel angles and timber mats. No concrete is involved. HydroOneowns almost "

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TIPS NEWS &

approaching Winterwas fast "

After the helicopter patrol found the problem, a ground-based patrol went out to assess the situation. The site is marshy and during the winter the frost heaves the ground up and down. This movement tore some of the diagonals off of the grillage footing. Without the support of the diagonal members, the main foundation legs bent and the foundation began to give way. Three structures had partially collapsed, but they hadn’t completely tipped. A quick repair was required to prevent a complete failure of the foundations, but access to the structures with large equipment/crane was not possible without extensive road construction. Instead, a temporary repair was made. Our travelling line crew out of Sudbury installed blocking to carry the weight of the structures, until permanent repairs could be made. Deciding on a Solution Back in the 1980’s, Hydro One had used some CHANCE ® piles under similar conditions, but no one who worked on that project was still around and the work was not well documented. But, after reviewing the situation, it was decided that horizontal beams welded onto helical piles would be the best option. With this approach, we would not need to excavate or remove and replace the existing foundations. Therefore, we would not need to bring in big earthmoving equipment. Winter was fast approaching and it was too late to do anything else in 2008.

" and itwas too late todoanything in2008.

Members that were broken off by ice

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We knew that Hubbell Power Systems had taken over Chance and we have a good relationship with our Hubbell representative, Roger Melanson, so we called him and he said he could definitely help us out. He put us in contact with Shawn Downey, a Hubbell helical pile and anchor expert, who came out for a site visit in early 2009. For that meeting, we brought in Hydro One’s Engineering Design Team. Together, they reviewed the soil characteristics and defined what load the piles would have to support. (Knowing that we would need good load bearing data on the soil at the site, we drilled pins into the ground and measured the torque. What we found was about 7 feet of poor material and below that good, load-bearing clay.) The team also considered the length of the pile sections. There were some concerns about clearance with the tower during installation. Consideration was also given to the torque capacity of our drive motor. After the meeting, Shawn Downey went back and designed an anchoring system that would meet all of our requirements. He was very accommodating.

HydroOnealsoconsideredallpossibleenvironmental issues and concerns. Thankfully, the site was not in a “special treatment area.” That is something we check anytime we need to enter a right-of way. The Big Fix Permanent repairs were made early in 2009. The work was performed by the Sudbury Travelling Line Crew under the direction of Rob Beange. Rob is the Crew Supervisor (or Union Trade Supervisor II as it is referred to at Hydro One). Rob and his crew came up with some innovative ideas that allowed the work to be safely and effectively executed. It was a really good project. It was something interesting, and I know the crew enjoyed the work. The crew installed the piles at the three towers in two days. The work would have been finished sooner, but there was some distance between the towers. It took one day per tower to finish the work. To begin, a drive motor was installed on an excavator, which was used to install the helical piles through the weak soil and into the underlying clay. The crew used an excavator rather than a radial-

Marshy landand tight clearancesmade the job morechallenging.Note the jigon the right that lets the drill operator visuallycheck thedrillingangle.

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TIPS NEWS &

At thispoint, all four helical pileshavebeen driven intoplace.The next steps areexcava- tion, cuttingandweld- ing the I-beams.

boom digger because the operator could better control the drive motor and could install the piles at a more precise angle.

The crew also built a jig to use as a visual reference. The jig was a tripod with the legs angled at the correct drilling slopes (in two different directions). The drill operator could compare the angle of the piles he was driving to the slope of the jig. Angle was important because the helical piles had to be fairly close to the base of the tower at the top, but they had to taper away from the tower to provide lateral stability and to clear the grillage foundation below it. The operator screwed the piles down until the required torque was reached. That occurred at various depths but on average were about 20 feet down. The lead section of the helical piles was 10 feet long (including a 7-foot by 2-inch- square solid shaft with helix plates 10, 12 and 14 inches in diameter topped by a 3-foot by 8-inch-diameter pipe/box- coupler section). We then used two extensions, each 10 feet long and 8 inches in diameter.

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Jackingup a 500kV tower.

Once driven in, workers cut off the piles horizontally at the precise elevation that would allow for the installation of the beams — without requiring us to change the elevation of the tower. Once the I-beams were welded in place, they had to be perfectly horizontal and all the I-beams under each tower had to be at exactly the same elevation. To do this, one of our technicians used a laser level. (We ended up raising the towers a bit — about half of a 3⁄4-inch bolt hole. That was just enough room to wiggle the bolts out.) Hydro One also hired a welder to weld the I-beams across the piles perpendicular to the direction of the line. These beams became the platform for the first set of temporary I-beams that were placed parallel to the direction of the line and used as a base to jack up the towers. Then, workers cut the top part of the grillage off below grade (the rest was left in place) and, permanent support beams were slid in, under the tower, and welded in place. The tower was then lowered onto the new beams and the guy wires were re-tensioned.

We did not have to do much excavating during the project, nor did we want to. At that site, once you dig a hole, it fills with water. We were lucky at a couple of locations: We dug about 2 feet and there was not too much water coming in. It was the welder who suffered the most. He had to lie on his back — in the hole — to weld the beams to the piles after grinding the galvanizing off of the piles. All work was complete by August 2009, and we have not had any more problems with frost heave at those sites. Documenting the Work This project was carefully documented. The engineers determined and recorded all the weights and tensions for the work and then we created a job document – a step-by-step guide of what we were going to do. When the work started, a Work Methods Technician came out to the site to document the work on the first structure. We now have a well documented job procedure ready for the next person who — 20 years from now — has to do the same thing.

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TIPS NEWS &

Except for thebackfill, all work is complete.

The finishedproduct.

For details on CHANCE ® Helical Foundations, contact your local Hubbell Power Systems representative or see our Catalog Section 4B at http://www. hubbellpowersystems.com/ catalogs/anchoring/

Doug Hudspeth, the author, graduated from Mohawk College of Applied Arts and Technology in 1987 as an Electrical Control Engineering Technologist. He worked for a short time at a steel manufacturing plant before joining Ontario Hydro (the predecessor to Hydro One) in 1988. He worked on a variety of transmission line maintenance projects as a Technician before becoming Manager of the Transmission Line Technicians.

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For more details on Test Terminals, contact your Territory Manager or visit us at www.hubbellpowersystems.com

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For more details on Auto-Ranging Voltage Indicators, contact your Territory Manager or visit us at www.hubbellpowersystems.com

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TIPS NEWS &

Upgrading Surge Protection Past Behind: Leaving the By Denny Lenk Principal Engineer Hubbell Power Systems

Based on the article "Surge Arresters: Utility Surge Protection Upgrade Considerations," Published in NEMA electroindustry , July 2011, page 14.

U

tilities typically begin large scale improvements to their surge arrester ‘fleet’ in one of two ways: When they rebuild their system following a wide-scale disaster and after they realize that older arresters can significantly reduce system

reliability and efficiency.

For example, the tsunami in Japan and the recent severe tornado activity in the United States caused devastating damage to life and property. These violent, natural events also severely damaged the electrical grids in these areas. In Japan, the damage sustained by the three nuclear plants received major news coverage because of the environmental issues associated with the potential of nuclear meltdown. What did not get prime- time news coverage was the massive amount of work needed to repair and rebuild the damaged electrical infrastructure. • Voltage Generation at low voltage (LV) level (fossil fuel/nuclear generating plant, hydro dam, wind farm, or solar panels) • Transforming from LV generation to high voltage (HV) transmission voltages • Transmission of HV from generation to load (customer location) • Voltage transformation back to LV distribution (for residential or commercial use) The electrical grid consists of several important segments, including:

345kVSystemGappedSiCArrester

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MobileSubw/gappedSiCArrester

(SiC block). These critical components were assembled inside a sealed porcelain housing, to insure electrical integrity in all environmental conditions. In this design, the gap performed the gap- spark-over function, while the non-linear resistance SiC block limited the magnitude of the the arrester current, allowing the seriesconnected gap to reseal. Unlike a fuse which, by design, fails open when it operates properly (necessitating replacement), the surge arrester is designed to perform its protective function repeatedly without failure. The implementation of gapped, SiC surge arresters was critical to assuring that the equipment installed on the new HV systems had the best possible protection against potentially damaging overvoltage surges. The mid-1970s marked the introduction of the metal oxide varistor (MOV), which has a much higher exponent of non-linearity when compared to the silicon-carbide blocks. Because of the excellent non-linearity of the MOV, this next generation surge arrester was designed without internal gaps. At system operating voltage, the MOV gapless surge arrester appears as a high resistance to ground. When exposed to an overvoltage surge (lightning strike, for example), the MOV discs become highly conductive (turns on). Continued>>

In each of these segments, proper performance of installed electrical power equipment is critical to the reliable and efficient delivery of electricity to the end user. Surge arresters help insure this performance. Reliability Under normal operating conditions, the reliability of the electrical grid is enhanced by the installation of surge arresters adjacent to each piece of power equipment. The sole purpose of the surge arrester is to protect the electrical insulation of the adjacent equipment from potentially damaging over voltage surges, by diverting the over voltage surge away from the equipment and through the adjacent surge arrester. If not diverted, the over voltage surge could damage the equipment. A lightning strike, on or near a power line, is a typical type of over voltage surge. Surge protection can be achieved in a number of ways. In the late 1800s, surge arresters took the form of a simple rod gap, installed across the power equipment. While these simple devices adequately protected equipment on the early low voltage (LV) distribution systems, they could not reliably protect equipment installed on higher voltage (HV) systems, which evolved as the electrical grid grew. The transition of the grid to higher system voltages was critical to efficiently transmit power from the often remotely located generating plants to the end users. As system voltages increased from LV toward ultra high voltage (UHV) 800-kV, arrester manufacturers have continuously improved arrester designs to assure that the expensive HV equipment (like transformers) was properly protected. In the United States, the post WWII period (from the late 1940s through the mid 1970s), marked the start of the ‘modern era’ of surge arrester design. Arrester manufacturers introduced the first gapped silicon-carbide (SiC) surge arresters, which used internal spark gaps with a precisely controlled, spark-over response characteristic. Connected in series with each gap assembly was a non-linear resistance element

230kVSystemGappedSiCArrester

MobileSubw/gaplessMOVarrester

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TIPS NEWS &

Reduce System Losses It should also be noted that all HV surge arresters, by design, dissipate power from the grid when operating at normal system voltage levels. For the gapped SiC arrester, the continuous power loss is a result of high resistive current flowing through the arresters grading resistors. MOV gapless surge arresters do not require this resistive grading structure. Comparison tests have confirmed thatMOV arresters consume less continuous watts from the grid than comparably rated gapped-SiC arresters. This energy saving feature is consistent with the government’s mandate for utilities to reduce energy losses on the grid. As an example, replacement of a single early

It redirects the surge to ground and, in doing so, limits the exposure of the equipment’s insulation to acceptable voltage levels. MOVs: Improved Protective Margin and Higher Energy Capability While the gapped SiC arresters provided state-of-the art protection when manufactured, recent testing has confirmed that the MOV gapless arresters, manufactured since the mid-1970s, actually provide improved performance characteristics. The most important improvement provided by gapless MOV surge arresters is their inherently lower protective levels, critical to extending service

. . . replacement of a single early 1960s vintage 120-kV rated gapped SiC arrester with a similarly rated MOV gapless arrester would result in an annual energy savings of more than 1000-kWh.

life of aging, possibly degraded, electrical insulation of power equipment that has been in service for many years. Replacement of gapped SiC arresters with gapless MOV surge arresters is a simple, cost effective way of extending the service life of expensive, aging equipment and, at the same time, minimizing unplanned power outages. For example, replacement of a gapped SiC by a new gapless MOV surge arrester on an older 69-kV transformer would be less than 2% of the cost of transformer replacement. Similarly, for an older 345-kV station, arrester replacement would be less than 1% of the cost of replacing the transformer. Gapless MOV surge arresters also have higher energy absorbing capability, minimizing the chance of failure, when discharging an over voltage surge. Laboratory testing indicates that HV MOV gapless arresters have an energy discharge capability approaching twice that of comparably rated gapped, SiC arresters.

1960s vintage 120-kV rated gapped SiC arrester with a similarly rated MOV gapless arrester would result in an annual energy savings of more than 1000-kWh. It is estimated that a large quantity of gapped SiC high voltage surge arresters may still be installed on utility power systems. Some utilities understand the benefits of gapless MOV arresters versus old style gapped SiC arresters and have initiated replacement programs. Others have little or no information on these 30-50 year old surge arresters. To address this concern, the NEMA 8LA Surge Arrester Section has developed a web site http:// www.nemaarresters.com/, targeted to provide information on gapped SiC arresters, including an identification guide and detailed discussions of arrester replacement considerations.

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D I S T R I BUT I ON PROT E C T I ON CUTOUTS

27kV Polymer Cutout ANTI-CORROSION

Mechanical-assist for drop-out function • Designed for high-corrosive environments like seacoasts, roadsides, industrial areas.

• A torsional spring aids the cutout drop-out operation when the fuse link melts. Extra protection for corrosive areas • Stainless-steel components available include inserts, hoods and bolts. • Loadbreak hooks also are available in a copper alloy.

FUNCTION-DRIVEN reasons why Hubbell polymer cutouts are superior • ESP hydrophobic silicon-alloy rubber with tracking-resistant toughness. • Light in weight, easy to handle and install. • Hardware crimping technology and chemical bond interface to polymer weathershed for maximum mechanical and electrical performance.

Torsional Spring for corrosive areas

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Hubbell Cabinets are thoroughly tested to meet the most rigorous industry standards • ANSI C57 Pad Mount Equipment Integrity • ASTM & UL-94 Flammability • ANSI/SCTE 77 Chemical Resistance • ASTM G154 UV Resistance • Hubbell box pad sidewall loading criteria

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A U T O M A T I O N R E A D Y S W I T C H E S

The Original Our AR Switch

ORIGINAL FEATURES: • Full 900A continuous & interrupt level • Four-link overtoggle operating mechanism • 1X 25kA and 3X 20kA fault closing • ¾” ice breaking • Hubbell proprietary ESP™ polymer insulators ADDED SINCE INTRODUCTION: • Full automation including auto-restore • Enhanced hookstick operation Imitated But Never Equaled From its inception, the AR has continued to bring significant innovations to the gang operated switch market.

AROverheadSwitchwith ADMOmotoroperator— eitherdown-the-pole orcrossarm-mounted.

THE ORIGINAL . . . ACCEPT NOTHING LESS Other brands have complimented the AR by copying it. But it’s still the most cost-effective, feature-rich, gang-operated switch available.

• Inverted mounting • Improved contacts • More enhancements coming soon

For more information on Hubbell switches, contact your Territory Manager or visit us at www.hubbellpowersystems.com

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Hubbell TIPS & NEWS is published to inform personnel of electric utilities and associated companies of new ideas and techniques in transmission and distribution practices. The magazine, under different titles and formats, has been published since 1932. Your suggestions, editorial or photographic contributions are invited and may be submit- ted to Hubbell TIPS & NEWS. TIPS NEWS & ®

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VOL. 16 No. 2 | April 2012

w w w . h u b b e l l p o w e r s y s t e m s . c o m

TheCHOICE isYours. Hubbell Power Systems Introduces FormedWire

• 350 Plus part numbers and growing! • Comparable to your current formed wire solutions • Reduce minimum billing or freight allowance by adding formed wire purchases to your present Hubbell order. • Competitive product offering with market-level pricing • Product offering includes: Deadends, Top Ties, Super Top Ties, Double Support Ties, Side Ties, Double Side Ties, Quik-Wrap™ Side Ties, Spool Ties, Quik-Wrap™ Spool Ties, Plastic Ties. • Meets or exceeds the strength requirements of the NESC

Contact your territory manager about customizing a solution for your next project

Allen 04/12

Order Catalog #FW-1