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PREVENTION OF WIND TURBINE FIRES

05 Dec

Automatic fire-suppression equipment has been developed to protect critical components in wind turbines regardless of location. The systems work without need of external power so it can activate around-the-clock without requiring manual activation or monitoring.
Some claim to require no maintenance. One design starts with a cylinder filled with an extinguishing agent. A long length of leak-resistant and proprietary polymer tubing loops around likely heat sources to serve as a pneumatic heat-and-flame detector immune to shock and vibration. The tube provides a temperature-sensitive detector and suppression delivery device. When exposed to a fire’s heat and radiant energy, the tube bursts and directs the extinguishing agent to the fire’s source before it can take hold and do extensive damage to the turbine.


Instead of trying to protect the entire turbine, these area-specific systems protect critical areas most prone to fire, such as electrical enclosures, near generators, and adjacent cabinets housing controls or electrical transmission equipment. Such systems can also protect brakes, generator enclosures, SCADA [Supervisory Control and Data Acquisition] systems, and hydraulic systems with potential to rupture near points of potential ignition.
The design is said to overcome major drawbacks of traditional flooding suppression systems. Vibration can loosen connections on traditional systems, rendering them useless, while dirt, dust, and temperature extremes are known to cause false alarms and false suppression discharges. This can result in the unwarranted disabling of the detection and suppression system, leaving the expensive turbine vulnerable to damage or destruction by fire, or the unnecessary additional cost incurred accessing the turbine.
Other ways to guard against fire or electrical shock, or both, is with ANSI Type 2 arc-resistant low voltage switchgear. It is intended to keep human life and building infrastructure safe in the event of arcing. One unit connects up to 32 network protector relays through shielded twisted-pair cable. It is rated for harsh- environmental stresses typically found in underground vaults. The arc-resistant, low-voltage switchgear protects against arc faults in breaker, bus, and cable compartments with no increase in footprint. It protects operating and maintenance personnel from dangerous arcing faults by redirecting or channeling the arc energy out the top of the switchgear, regardless of the origination location of the arc.
Reducing combustible or smoke-generating material in the nacelle further reduces the chance of fire. To that end, a recent thermoplastic polyurethane (TPU), for wire insulation, generates less smoke than conventional insulations in the case of arcing or fire. The material is intended for wire and cable jacketing in nonhalogen, flame-retardant applications. Industry is placing greater emphasis on the development of new compounds that produce less smoke and higher Limited Oxygen Index (LOI) to reduce the spreading of flames. This TPU is said to meet industry’s demand for wire and cable jacketing used in applications that need low-smoke fire resistant materials. The material provides an LOI of 33 and achieves a UL vertical burn rating of V0. Low-smoke TPUs also feature greater resistance to abrasion, wear, tear, and puncture than materials such as rubber or PVC.

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Posted by on December 5, 2011 in RENEWABLE ENERGY

 

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