Ergodyne
www.ergodyne.com

Windpower Engineering & Development

Viasala also provides the free lightning explorer (shown). The company owns and operates the GLD360, and delivers lightning information as a service, letting users access data without capital expenditures. The company has more than 90 precision networks installed in 40 countries, including the US National Lightning Detection Network (NLDN).

The Vaisala GLD360 network’s global reach, its industry leading Location Accuracy (LA) and Detection Efficiency (DE) performance combined with its unique Polarity & Peak Amplitude (kA) measurement capability provide more accurate short and medium-term weather forecasts. The network can detect and characterize lightning in areas where meteorological observations may be partially lacking or absent. It supports lightning as a radar proxy or radar complement in areas where weather radar information is limited or non-existent. The network provides operational situational awareness to numerous industries.

GLD360 assimilates lightning data into weather models that enhance the foresight of advancing weather systems, which helps users make more informed decisions and increase safety and efficiency,” states Richard Pyle, Director, New Weather Markets in Vaisala.

Vaisala
www.viasala.com

Windpower Engineering & Development

Chill-Its 6670CT evaporative cooling hard hat with neck shade and cooling towel keeps the sun off worker’s necks while delivering cool comfort. The evaporative cooling bandana (not shown) sports a breakaway hook-and-loop closure for a secure and comfortable fit.

The Chill-Its line uses the 6602 Cooling Towel in three versions of clever personal cooling head wear. It uses polyvinyl acetate (PVA) material in a lightweight, low-profile device that activates quickly by submerging it in water for less than one minute. The result, says the developer, is hours of cooling relief. Three new products provide a superior chill without the added bulk, weight and slime of conventional cooling solutions. The material eliminates the sausage-like bulkiness found in traditional cooling devices and instead offers lightweight, low-profile cooling solution.”

Ergodyne
www.ergodyne.com 

Windpower Engineering & Development

The LEDBEACON3 from TWR Lighting is one product of LED light developments. It consumes less than 6W. The company also provides remote monitoring equipment for several MET towers with the DM900 Wireless Remote.

The FAA provides guidance for the voluntary marking of MET towers erected in remote and rural areas that are less than 200-ft AGL. This guidance will enhance the towers’ visibility for low-level agricultural operations. First, if towers are not going to be lit for visability during both day and night then they should be painted in alternating bands of aviation orange and white paint in equal width with bands at the top and bottom ends colored orange for daytime marking. Second, towers should have high visibly sleeves installed on the outer guy wires for daytime marking. Third, towers should have high visibly orange spherical marker balls attached to the guy wires for daytime marking. Fourth, they will be lit with an appropriate FAA approved lighting system for nighttime marking. The FAA intends, at a future date, to amend the advisory circular AC70-7460-1K to include guidance on sleeves.

The FAA requires a sponsor to submit FAA Form 7460-1 for all structures over 200 ft. The FAA then reviews the location, height, and hazard to aviation, and provides its determination along with their marking and lighting recommendation.

It’s not hard to see how unmarked MET tower could blend into background haze. Towers less than 200 ft once required no marking or lighting. This changed with an agricultural pilot’s fatal collision with an unmarked MET tower in January 2011.

The Advisory Circular AC70-7460 provides guidelines for marking and lighting structures for daytime and nighttime hours. Painting the structure as discussed or using a white medium intensity (MI) flashing light increases daytime conspicuity. Red or white MI flashing systems provide nighttime visibility. However, a white flashing light (L-865) at night is not community friendly.

MET towers from 200 to 350-ft AGL require a red MI obstruction lighting composed of one flashing omnidirectional beacon (L-864) at the top of the structure and two or more steady burning (L-810) lights at the intermediate level for nighttime conspicuity.

MET towers from 351 to 500-ft AGL require a red MI obstruction lighting composed of one flashing omnidirectional beacon (L-864) at the top of structure, two flashing omnidirectional beacons (L864’s) at the mid-level, and three steady burning (L-810) lights at the one-quarter and three-quarter levels for nighttime conspicuity.

These lighting systems must be monitored every 24-hours by visual or automatic means. It is extremely important to visually inspect obstruction lighting in all operating intensities at least once daily. When using remote monitoring devices, the communication status and operational status of the system should be confirmed at least once daily. For each structure, a daily log should be maintained to record the lighting system’s status.

A few companies like ours offer an optional monitoring service that includes filing the FAA Notice to Airman (Notam) with Flight Service Station (FSS), notifying particular company personnel of site issues by email, phone call, or fax, along with removal of Notam after resolving a site issue, and monthly electronic site reports.

Wind turbines are fairly obvious but MET towers are less visible. TWR’s Lighting & Solar Systems meet the requirements of FAA’s Engineering Brief # 76, which requires seven days of autonomy. The company also provides wire sleeves and marker balls to provide complete MET tower marking and lighting.

The major challenge in lighting MET towers has been the unavailability of local utility power in areas where utility-scale wind farms are planned. Therefore, the towers need power from a temporary source.

Previous generations of obstruction lighting have used incandescent lamps, strobe tubes, and quartz halogen lamps as light sources which are neither energy efficient nor practical for use with solar power. Thanks to advancements in light-emitting diodes (LED), the industry can replace the power-hungry light sources with LEDs, which consume considerably less. One result is the MI L864 LED Beacon (LEDBEACON3) that consumes less than 6W. This system still meets or exceeds all photometric requirements of 2,000 Candela red-light output.

LEDs also allow economically powering obstruction lights with solar panels. This temporary power source has become a preferred choice with several companies providing wind assessment. The setup consists of batteries to power the lights and solar panels to charge the batteries.

TWR Lighting has developed an MI Red LED Lighting System operating on 24 Vdc, the lowest power consumption available. A light kit (part number LK1A1MET24VDC) consumes only 142W over a 24 hour operating period. This power consumption is about 25% of what our 120-Vac MI System consumes.

The 24-Vdc lights can be powered by a 175-W solar panel across all U.S. regions. The company has partnered with a solar-panel supplier to provide an MI lighting setup with solar panels for less than $10,000 per installation. WPE

By: James Syzdek, Director of Business Developmen-Wind Energy, TWR Lighting Inc., Orga Aviation Lighting Inc.

Windpower Engineering & Development

The program is for engineers and those developing programmable electronic safety systems and products based on the IEC 61508 standard. The training imparts basic knowledge so developers can effectively implement safety related requirements.  Attendees will also learn about important new aspects of the IEC 61508 edition 2.

The program includes three days of training. Participants can take an optional exam on the fourth day to obtain an official verification of their expertise. After passing a final exam, attendees receive a TÜV Rheinland Functional Safety Engineer certificate which is acknowledged worldwide, stating that the student has gained specific knowledge within the field of Hardware/Software Design according to IEC 61508.

The four-day program is slated for June 18 to 21 at TÜV Rheinland’s Chicago office, 2100 Golf Road, in Rolling Meadows, Ill. The $2,950 cost includes the exam. A $2,650 charge omits the exam.

Tuv Rheinland
http://education.tuv.com/tuv-functional-safety-program.

Windpower Engineering & Development

Hammerhead Industries

www.gearkeeper.com

Windpower Engineering & Development

By: Tony Locker, Littlefuse, Inc., www.littlefuse.com

The primary and secondary terminals of a transformer in a nacelle may be monitored with light sensors as part of an arc-flash detection and protection system.

OSHA has stepped-up inspections as a result of several arc-flash events associated with wind turbines. The organization reports the investigation of 32 arc-flash accidents that occurred in 2009 at wind farms. According to the agency, total industrial arc-flash incidents cause about 80% of electrically related accidents and fatalities among qualified electrical workers. In 2010, OSHA investigated one such event that resulted in severe burns to a wind-farm technician and proposed fines of $378,000 for the employer, a service and maintenance company to the wind-energy industry.

Starting in 2012, OSHA will be targeting the wind-energy industry with one of its National Emphasis Programs (NEP). The agency announced that operation and maintenance of wind turbines are subject to the same regulations applied to traditional power-plant operations. In this regard, OSHA will apply 29 CFR 1910.269, that, among other things, requires safety procedures and use of personal-protective equipment and clothing consistent with NFPA 70E rules.

All this is good for workers in the industry and can save employers money in the long run. Industry estimates place average costs for the medical treatment of arc-flash survivors at around $1.5 million, and associated litigation costs up to $10 million. Still, inspections and fines do nothing to mitigate the effects of an arc-flash. Fortunately, commercially available electronic devices do.

Arc-flash mitigation
An arc flash occurs when fault current flows across an air gap and creates highly ionized gas. Left unmitigated, an arc flash can result in temperatures hotter than the surface of the sun, shrapnel traveling at more than 700 mph, and blast pressures exceeding 2,000 psi (higher than a shotgun blast). The danger to workers varies with each piece of equipment, depending on the available fault current, working distance, and the opening time of overcurrent protection devices in the electrical circuit.

A phase-to-phase fault in a 480-V system with 20,000A of fault current generates 9.6-million W. In the absence of arc-flash mitigation, if the arc persists for only 200 ms the resulting energy released would be 1.92 million joules. Consider:

E = V x I x t

= 480V x 20,000A x 0.2 sec

= 1,920,000 joule.

By way of comparison, TNT releases about 2,175 joules/gram when detonated. So the arc-flash described corresponds to the detonation of 863 grams of TNT. (One stick of dynamite contains 1,000 grams of TNT.)

In an effort to minimize injuries, conventional arc-resistant switchgear includes ducts intended to channel these explosive forces away from an operator. However, worker safety is still compromised because this solution doesn’t reduce the amount of energy in the arc-flash. What is needed is a way to extinguish the arc by interrupting the electrical current that feeds it, and do so more quickly than conventional overcurrent devices. There is a class of electronic-protective devices that do this, but the current-clearing time varies depending on design and how they are applied. These devices fall into three primary categories:

-Optical-flash detection plus intentional shorting of three-phase lines to trip a circuit breaker
-Optical detection plus intentional phase-to-ground faults to trip a breaker
-Optional-flash detection that directly triggers a circuit breaker trip.

Also, arc-flash pressure detectors can trigger a switch or trip a breaker that cuts current flow. But they would act primarily as a supplement where optical detectors may not be in a location to see the arc first. They can also help prevent nuisance tripping due to a flash of light from a source, such as a nearby welder, by comparing a pressure detector output to the optical light sensor output. However, there are timing issues to consider in their use.

An optical arc-flash sensor (circled) is located inside a typical switchgear cabinet.

Anatomy of an arc flash
When evaluating options to mitigate arc-flash, consider the timing in a typical event. In early stages, the arcing current is too low to trip a circuit breaker, which is sized to tolerate temporary rises in current caused by transients such as motor inrush current.

In an arc flash caused by a phase-to-ground fault, the insulation on the electrical cable catches fire in about 50 ms. Within 100 ms the copper conductor begins to vaporize and create a fully ionized plasma. This plasma will conduct a huge amount of current that continues to feed the arc-flash, generating an explosion of heat and light, along with a high-pressure wave.

Light is one of the earliest indications of a forming arc flash. In a mitigation device with an optical light sensor, the flash is detected as it begins to develop. The sensor’s output is used to trip a circuit that interrupts current flow.

As would be expected, an arc-flash pressure wave does not propagate nearly as fast as light, so a pressure sensor will not detect an input until long after a light sensor has already actuated. Moreover, a pressure sensor takes longer to respond to an input compared with a light sensor.

Protection strategies
One implementation of arc-flash reduction incorporates light sensors with the switchgear which is part of a wind turbine. When one of these sensor detects an arc flash, its output signal triggers a switch that short circuits across all three phases of the switchgear bus. This then trips an overcurrent-protective device (usually a circuit breaker). One drawback to this approach is that shorted phases may draw so much current that it destroys or inflicts costly damage to the switchgear and associated equipment.

The PGR-8800 from Littlefuse provides an example of an arc-flash relay and associated sensors.

Another switchgear approach uses the optical sensor output to trip a switch that causes a large fault between each phase and ground. This draws current away from the arc-flash, because its air gap is a less efficient conductor that the intentional faults. Typically, this solution is installed inside a switchgear vault and is used to trip a circuit breaker that can interrupt current flow. This design does not draw as much current as phase-to-phase shorts, so it poses less of a threat in terms of equipment damage, assuming a newly created arc-fault is contained within the vault.

Because both approaches make arc-flash suppression part of the switchgear, retrofitting a solution to existing equipment is impractical and buying all new switchgear to obtain arc-flash mitigation is cost prohibitive. On the other hand, large existing switchgear cabinets often have enough space to allow retrofitting a separate arc-flash relay from a third-party source.

Arc-flash relays are microprocessor-based devices that also use optical sensors to detect the onset of flash. They respond within about 1 to 5 ms at light intensities of about 10,000 lux or higher. Within that timeframe, the optical sensor output can actuate a switch or circuit breaker in either of the ways mentioned to cut off current feeding the arc. The overall current-clearing time depends on the protection strategy and the performance of the external switch or circuit breaker used.

The wiring diagram is an example of an arc-flash relay installation in a wind turbine electrical enclosure, along with its fixed-point (A) and fiber-optic (B) light sensors.

Clearing time and equipment damage are the tradeoffs consider when choosing a protection strategy. For example, should the protection-scheme short the phases, or simply actuate a circuit breaker to interrupt current flow? If the arc-flash relay triggers a switch to short the phases, it will typically interrupt current flow to the arc within 30 ms. However shorting phases risks severe damage to the switchgear and associated equipment.

Using the breaker as a switch prevents transformer damage, but typically takes 50 ms or longer, depending on the reaction time of the user-supplied circuit breaker. This strategy may allow minor damage at the fault point where the arc originates, but not the severe damage of a full-blown arc-flash. Using a circuit breaker also eliminates purchasing and installing a separate switching device.

Therefore, depending on the strategy used with an arc-flash relay, the overall time from light detection to current flow interruption typically is in the range of 30 to 50 ms. The result is a large reduction in the amount of energy released through an arcing fault, less damage to equipment, and fewer and less severe injuries to nearby personnel.

Still, one concern with using arc-flash relays is avoiding nuisance trips. One way of handling them is to use phase-current transformer inputs to the arc-flash relay’s microprocessor. Current transformers are placed to measure the three-phase currents in the system. If the microprocessor logic receives an input from a light sensor, it checks for a rapidly rising input from the current transformers. If present, it sends an output signal to the disconnect device.

Some arc-flash relays also allow adjusting their light sensitivity, although most do not. Sensitivity is usually set at the factory at 10,000 lux. An arc emitting light below this level is not terribly dangerous. Nevertheless, it can be useful to raise the setpoint to help avoid nuisance tripping. For example, a worker welding nearby could inadvertently set off the relay, causing downtime and equipment damage if current transformers are not used.

The table provides some comparisons to different levels of lighting commonly found in the environment, which were taken into account in setting 10,000 lux as an arc-flash relay trip point. Even with current transformers, if an arc creates a flash of slightly less than 10,000 lux the system must rely on other protective devices to interrupt current flow to the arc, such as an overcurrent relay or fuse. A lightly overloaded fuse, for example, will interrupt current flow within about two seconds, about the time it would take nearby personnel to move off a safe distance. According to the IEEE 1584 Standard, an arc-flash of this intensity lasting for two seconds will expose nearby equipment and personnel to about 0.75 cal/cm2 of heat. This is not enough to create second-degree burns on human skin. The NFPA 70E Standard defines the threshold for its Risk Category 0 as 1.2 cal/cm2.

Typical Light Levels

Arc-flash relay installation
Arc-flash relays are installed in wind-turbine switchgear cabinets and switchgear at the base of the tower near bus bars in the control cabinet and the transformer. Most use multiple fixed-point light sensors near vertical and horizontal bus bars where arcing faults are more prone. Enough sensors should be installed to cover all maintenance areas, even if policy is to only work on deenergized systems. At least one sensor should have visibility to an arc fault if a person blocks another sensor’s field of view.

Light sensors may also be installed in other electrical cabinets and on panels that are subject to routine maintenance and repairs. In addition to fixed-point sensor inputs, at least one company (Littelfuse) also supplies fiber-optic sensors that have a 360° field of view for detecting light. This allows more flexible positioning of the light sensing locations, because fiber-optic strands can be looped throughout an enclosure or panel to cover challenging component layouts. One arc-flash rely, for example, the D1000 from Littlefuse, allows up to 24 light sensor inputs to comprehensively monitor any electrical equipment configuration. A USB port is also provided for setup from a remote PC, to access event logs (trips and the sensor inputs that caused them), and generate graphs of current data. WPE

Windpower Engineering & Development

The service lift from Avanti Wind Systems has a 533-lb capacity, enough for two techs and tools. To minimize welds for lift guides, the two wire ropes (on the side of the blue cage) that lift the platform are tight enough to maintain lift stability. The company says it has produced and installed more than 16,000 service lifts in wind-turbine towers worldwide.

Several states have required that service lifts in wind-turbine towers meet the same requirements and standards as elevators in buildings. Therein lies a problem. “It’s not possible,” says Avanti Wind Systems General Manager Kent Pedersen. “For example, there are a lot of welds in elevators and elevator shafts in buildings. In a wind-turbine tower, however, the lift is cable driven and guided because the tower must have as few welds as possible for the sake of its safety and structural complexity.”

This is one reason members of National Association of Elevator Safety Authorities (NAESA) from several central-region states attended a seminar regarding safety of service lifts in wind-turbine towers. The purpose of the seminar was to introduce elevator inspectors to the wind industry and expose the wind industry to existing and new elevator compliance. More than 40 certified elevator inspectors participated.

Service lifts, sometimes called work cages because techs occasionally work from them, also provide safe and fast access to the top of the tower.

Currently, several states follow rules that say an elevator inspector must give official approval before a service lift is used in a wind tower. “Consequently, it’s important for inspectors to know the safety considerations and training that we provide for our lifts and ladders,” says Pedersen. “They should know the difference between an ordinary elevator in a building and the details of a service lift in a wind tower,” he says.

Safety ladders and service lifts work well together in turbine towers, each providing support for the other.

Requirements for service lifts in wind turbines vary from state to state, but a new national standard in a final review stage is expected to take effect in 2012 or 2013. Once adopted, the new standard will ensure the same requirements nationwide. “More importantly, it will further enhance the safety of the technicians working in wind-turbine towers,” says Pedersen.

The coming standard was a big part of the discussions and presentations at the seminar. Most states require an approval of every service lift before it is put into use. The lift must be tested by a certified inspector and it must be inspected at least once a year like other safety equipment in wind-turbine towers. This is done by lift manufacturers such as Avanti Wind Systems, technicians authorized by the company, or a certified inspector. Anyone working in wind-turbine towers should meet the safety rules issued by authorities and owners of the wind farm. This also applies to official elevator inspectors. WPE

By: Kent Pedersen of Avanti Wind Systems, www.avanti-online.com

Windpower Engineering & Development

The RT3-5601 tether extends up to 42 in. and to reduce arm strain, the tether features a ratcheted thumb-controlled device to lock the cable at extension length. Also, the Dual-Axis rotation clamp-on clip attaches easily to a tool belt or fall protection harness. The universal movement of the dual action clip minimizes resistance and line wear to extend the tether’s life.

The RT3-5601 retractable tether, for tools up to two pounds, is valuable when working in close quarters or climbing. Available in high-visibility orange, the retractable tether’s ultra low profile keeps tools close to the body when stored while still allowing complete accessibility in all directions when in use. The tether’s patented side-release clip improves productivity while maintaining drop safety by providing a method for easily exchanging one tool for another.

The RT3-5601 has a balanced recoil and retraction force. When the retractable tether is extended for use, only minimal force is necessary thereby avoiding worker fatigue or in the reverse, causing a ”kick” when the tool retracts. According to John Salentine, VP of Hammerhead Industries, “A properly tethered tool or instrument makes work more efficient and simplifies e repair, maintenance or manufacturing project.

RT3-5601 retractable tool lanyards including the dual-axis belt clip retail for $34.99 per unit. A free, four-page tool tether brochure containing the tethering guide and related information is available by calling Hammerhead Industries’ Customer Service at 888.588.9981.

Hammerhead Industries
www.gearkeeper.com

Windpower Engineering & Development

In addition to the colors shown, Gateway Safety has added blue-mirror lenses with black frames to the Conqueror line of glasses.

Conqueror Safety Eyewear has been certified by Underwriters Laboratories (UL) to meet the ANSI Z87.1+ high impact standard. This independent, third-party certification by UL is the extra step developer Gateway Safety takes to ensure quality and differentiate its products from alternatives.
An additional lens color has also been added to the Conqueror line: Blue Mirror, with a black frame. Superior comfort features include light weight, a soft rubber nose piece and ergonomic, contoured temple tips that prevent pinching. Each pair also comes with an adjustable-length retainer to keep Conqueror close for easy retrieval.

Organizations such as UL regularly test Gateway Safety products, including Conqueror safety eyewear, to meet ANSI Z87 standards. They also have the authority to inspect UL-listed Gateway Safety product or production facility without advance notice—to ensure ongoing compliance with the ANSI Z87.1+ standard.

Gateway Safety Inc.
www.gatewaysafety.com

Windpower Engineering & Development