Tech Briefs

Issue 6 and Volume 28.

HydroVision International announces call for abstracts

PennWell Corporation, organizer of the HydroVision International conference and exhibition, is accepting abstracts for the Technical Papers program. The conference will be held July 27-30, 2010, in Charlotte, N.C.

 Abstracts are requested on all topics of interest to technical professionals in the hydropower field. Preference will be given to abstracts that focus on innovative, practical, and proven technologies and methods.

Abstracts that describe the focus and content of proposed papers (maximum of 400 words) are due October 30, 2009. Submit abstracts through the Internet at: www.hydroevent.com.

All abstracts submitted will be reviewed by the conference Technical Committee. If accepted, authors will be invited to submit a paper by April 30, 2010, for inclusion in the official conference publication (in CD-Rom format) that will be distributed to all conference delegates.

— For more information, contact (1) 918-831-9736 or E-mail: [email protected]

System automatically triggers opening of fish bypass

An automated hydroacoustic control system installed at the 10.3-MW New York State Dam project monitors the presence and abundance of fish in the forebay and opens a bypass gate. Project owner Boralex installed the system to improve downstream passage of blueback herring.

The system consists of nine networked active acoustic (SONAR) transducers arrayed upstream of the powerhouse both above and below the turbine intakes, according to Daniel McCarty, manager of hydro operations at Boralex. These transducers are connected to a computer that activates relays to control opening and closing of a bypass gate. This gate is located between the powerhouse and the overflow section of the dam.

The transducers take measurements every ten minutes to determine approximate fish density, McCarty says. The greater the density of blueback herring sensed, the greater the opening of the bypass gate. For example, if the most upstream transducer senses a density of ten or more fish per square meter of water, it triggers a gate opening that allows 160 cubic feet per second (cfs) of water to flow downstream. If the transducers above the turbine intakes detect a density of ten fish per square meter, the gate is triggered to open and allow 307 cfs of flow. The trigger level for the transducers below the turbine intakes is five fish per square meter, with a resulting bypass flow of 377 cfs. The gate will continue to open until a maximum flow of 491 cfs.

Up to this point, Boralex is allowed to operate the turbines at full capacity. If the transducers continue to detect a high fish density, the company must scale back power production in steps, cutting it down by 25 percent, 50 percent, 75 percent, and finally 100 percent. These measures for downstream passage of blueback herring during their migration season in September and October are in accordance with the project’s Federal Energy Regulatory Commission (FERC) operating license, McCarty says.

When fish abundance sensed by the transducers begins to drop below the trigger levels mentioned above, the utility can again generate power. When measured fish density drops below the ten-fish-per-square-meter level at the upstream and top of the powerhouse transducers and five-fish-per-square-meter level at the transducers below the powerhouse intakes, the system closes the bypass gate until a minimum of 160 cfs is passing.

Before installing this system, Boralex’s only option was to keep the gate open and allow spill from May 15 to December 1, McCarty says. The hydroacoustic control system allows the company to reduce spill when fish are not present to pass and allows periods of generation when fish are passing the dam.

BioSonics developed the system being used at New York State Dam and worked with Boralex to implement and install the system.

USSD releases white paper on rock scour of dam foundations

The U.S. Society on Dams (USSD) announces availability of a white paper, “Rock Scour of Dam Foundations.”

Scour of rock downstream of dams that have been overtopped has become a dam safety concern in recent years, the report says. It also says that the magnitude of design floods at dams can increase over time, requiring either an increase in spillway capacity or allowing overtopping of a concrete dam. Because the foundation downstream from a concrete dam can consist of intact rock formations, it may be necessary to show that the foundation will not scour excessively during flood conditions and endanger the dam, the report says.

The white paper summarizes the current state-of-the-art with regard to rock scour. This includes methods developed over the past decade to investigate the erodibility of rock formations subject to flowing water.

Topics covered in white paper include:

— Rock scour mechanisms;

— The erosive capacity of water; and

— Technology available to determine the effects of rock scour.

The white paper also contains a case study of Kariba Dam in Zambia, which impounds water for two hydro projects.

The USSD Committee on Foundations prepared the white paper.

— The white paper costs US$15 for USSD members and US$24 for non-members. To order, visit the website: www.ussdams.org/pubs.html.

Voith Hydro refurbishes coil facility in Canada

Voith Hydro has re-equipped and redesigned its coil production and servicing facility in Mississauga, Ontario, Canada.

The new facility, opened in May 2009, will be the sole supplier of hydro generator coils to all of Voith Hydro’s operations around the world, the company says.

Work to revitalize the facility included redesigning the entire coil manufacturing process and installing state-of-the-art equipment, Voith Hydro says.

Voith Hydro’s Mississauga facility has operated for 35 years. It contains a six-axis taping machine, looping machine, electric press, coil-forming machine, vacuum pressure impregnation system, and other equipment for multi-turn coil production. In addition, the company is investing in equipment for this facility for its after-market service business supporting generator and turbine components.

Canadian association releases electrical safety standard

The Canadian Standards Association (CSA) announces availability of “Electrical Safety in the Workplace” (CSA Z462). This is a voluntary standard on arc flash and electrical safety work practices. The goal of this standard is to assist employees and employers in more effectively managing electrical safety hazards, CSA says.

This standard specifies electrical safety requirements necessary to safeguard workers. Such activities include installing, operating, and maintaining electrical equipment. The standard describes safe work procedures, use of energy control systems, and how to determine the appropriate personal protective equipment for working with hazardous electrical equipment.

CSA developed this standard in collaboration with the National Fire Protection Agency (NFPA) in the U.S. CSA Z462 is intended to be an equivalent standard to NFPA’s “Standard for Electrical Safety in the Workplace” (NFPA 70E).

CSA is a membership-based not-for-profit association. Its goal is to develop standards to enhance public safety and health, improve the quality of life, preserve the environment, and facilitate trade.

— To order this standard for C$80 (US$64), visit the Internet: www.electricityforum.com/estore/csaz462.html.

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