Section VIII Safety

1. Section VIIISafety Reminder: This course Does NOT license students to install or energize equipment!

2. Public Safety Considerations • Primary safety considerations are due to movement of the rotor and accessibility of industrial equipment to the public. • There may also exist a fire hazard if a wind generator fails, bearings seize, or electronics fails.

3. Public Safety Considerations • Blade Throw • Rare but possible blade or blade fragment throw from a turbine • Turbine nacelle covers and rotor nose cones may also break loose These are rare occurrences and usually associated with extreme weather conditions! Blade throw calculations can be found in: Larwood, S., (2005) Permitting Setbacks for Wind Turbines in California and the Blade Throw Hazard, California Wind Energy Collaborative Report: CWEC-2005-01, Sacramento.

4. Public Safety • Falling Ice and Ice Throws • Ice can build up on blades, guy wires (tower supports) and the towers themselves. • As the ice melts and the rotor spins pieces can be dropped or thrown Ice Throw Review in Bossanyi, E.A. and Morgan, C.A. (1996) “Wind Turbine Icing- Its Implications for Public Safety,” Proc. 1996 European Union Wind Energy Conference, Goteburg, pp. 160-164.

5. Public Safety • Tower Failure due to structural weakness, foundation problems or tower guy wire failure (small turbines). • Wind turbine fatigue and failure of the mechanical parts are due to: • High Wind loads causing stress • Periodic loads from wind shear • Turbulence in the wind • Transient loads from gusts, and starting and stopping the turbine • Resonant vibrations in the structure

6. Public Safety • Attractive Nuisance • Persons (particularly teenagers) can be attracted by lattice towers and guy wires as possible climbing opportunities. Fences around the footprint of the guy wires is often necessary. • Access doors on large towers • Electrical panel doors Often, small turbines placed near schools or other publicly accessible areas use monopole towers instead of guyed lattice towers so there is no climbing opportunity.

7. Public Safety • Fire Hazard • Arid locations for turbines can also pose hazards for fire due to poor electrical equipment in the turbine causing sparks • Equipment striking power lines • Lightning Placing wiring and cables underground helps avoid the single biggest possible fire source.

8. Personal Safety • Large turbines, the most dangerous time is during construction or during mechanical and electrical maintenance. • Roads are built and graded, • Foundation ground is excavated and graded, followed by pouring of the foundation; • Tower sections are placed, assembled, and connected; • Blades and the electrical generator are installed, and the final system assembly is tested. • The work is very physical. Heavy equipment such as graders and cranes are used. Workers must climb ladders and be suspended. They depend on full body harnesses and lanyards, snap-hooks, carabineers, slings, and fall-arresting systems. Lifting parts or components depends on using properly rated and tested slings and rigging gear. • Turbines may need to be shutdown for normal mechanical or electrical maintenance, or during times when a part or sub-system fails or is damaged. • Working with a turbine rotor moving is a very dangerous condition. For that reason, maintenance should not be done and entry into or onto the tower or nacelle should not allowed if the rotor is moving. • Mechanical maintenance could include work on the supports, tower, turbine, nacelle, brakes, or blades. Brake failures, falls, and dropped equipment are some of the concerns while performing maintenance. • Electrical maintenance could include work on the wiring inside the generator or between the generator and the transformer. This is at high voltage is must be done only by highly trained practitioners. • Work in electrical cabinets could involve high voltages and is considered very dangerous. • Work on low voltage circuits such as instrumentation often has an associated possibility of shock but not burns or death as may occur with the electrical power circuits.

9. Personal Safety • Falling • The biggest safety risk related to wind turbines is definitely falling and was the cause of most of the 60 deaths reported since the 1970s. This includes falls from the tower itself, the nacelle (top part of the turbine) and the blade assembly. However, considering that more than 200,000 wind turbines are installed and operational throughout the world, the number of fatalities is not very high compared to many industries. Harnesses and fall arrest equipment are mandatory (OSHA). • Falling is a particular hazard when servicing small turbines atop towers from 30 to 100 feet in height. • Electric Shock • Another prime safety concern with wind turbines is electrocution (electric shock). All large wind turbines are equipped with brakes and shutoffs, minimizing the risk of electrocution while they are being serviced. The brakes assure that the turbine does not produce electricity (locks the rotor to a fixed position) and the shut-off makes sure there is no current path through the power lines of the turbine. • How Electrical Current Affects the Human Body , OSHA Construction eTool, US Occupational Health and Safety Administration, http://www.osha.gov/SLTC/etools/construction/electrical_incidents/eleccurrent.html • Section 1, Electricity Is Dangerous, National Institute for Occupational Safety and Health, http://www.cdc.gov/niosh/docs/2002-123/2002-123b.html