Important : Judgement comes from Supreme Court of India to install divertors on all existing overhead powerlines in potential GIB areas. The copy of the order is attached below.
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Guidelines - Bird Flight Diverter; Type & Installation Instructions as per Govt Agencies
For Great Indian
Bustard habitats and potential areas, as identified by
WII/MoEF&CC, one bird flight diverter shall be installed at every
10 m on the earthwire/ OPGW and one bird flight diverter shall be
installed at every 15 m on phase conductors in a staggered way
such that as a whole, the power line will have effectively one
diverter at every 5m to 6m. In case of bundled conductors, bird
flight diverters may be installed on the lower conductor of the
bundle in staggered manner.
1.3.6.2.12 BIRD FLIGHT DIVERTER
Bird diverters shall be placed in identified stretches as per the conditions stipulated by forest authority to avoid the chances of collision of birds with transmissions lines. These bird Diverters shall be placed on earth wire/OPGW in staggered manner (in case of power line having earthwire and OPGW or Both Earthwire/OPGW) at a distance of 10 m unless otherwise specified by forest/ wildlife authority in the middle portion of the identified spans leaving 50 m either side from tower and at least one bird diverter for spans up to 100m in both earth wire/OPGW. An indicative sketch of the placement of the bird diverter is attached in the drawing section of this specification.
The BIRD-FLIGHT Diverter shall be lightweight (weight not more than 500 gms each), shall offers little wind resistance and should be easily installed by hand or by hot stick or by any other suitable method. The bird diverters should retain good physical characteristics within a range of extreme temperatures i.e from -30 deg celcius to 100 degree Celsius. Contractor/subcontractor shall submit valid test report/test certificate for mechanical test, ageing test i.e solar radiation test & sand and dust test as per MIL-STD 810 F etc. from accredited third party laboratory for the design which they intend to supply. The grip on the earthwire/OPGW should ensure that the Bird-Flight Diverter remains in the applied position and does not move along the span under Aeolian vibration or other conditions.
Generally Suspended devices i.e Dynamic Bird Flight Diverters shall be used in the transmission line as bird diverters.
Bird flight Diverters shall have one warning disc which shall be attached to the wire through spring loaded clamp. Warning disc shall be made through injection moulding of UV stabilized plastic while the attachment clamp shall be made of UV stabilized engineered composite plastic. All fasteners and spring shall be of stainless steel.
Warning disk of Bird Flight Diverter must swing, sway and rotate and should have different coloured sun and moon light reflectors on both faces. Warning disk must glow in dark.
Diameter of circular warning disk shall not be less than 150 mm. If warning disk is quadrilateral or trapezoid, then shortest arm length should not be less than 90 mm. Thickness of the warning disc shall not be less than 3 mm. Minimum reflective area on each face of warning disk shall not be less than 50 % of the entire area subject to minimum 4000 sq. mm. All suspension hardware which are directly exposed (moving or static) must be corrosion free. Bearing swivel shall be made of stainless steel and should allow free spinning in minimum wind speed of 2 km/hour.
The clamp of the Bird flight diverter shall be made of UV stabilized engineered composite plastic. Spring type clamp, suitable for holding earth wire/ OPGW shall be used.
It shall be capable of supporting the Bird flight diverter during installation and prevent damage or chaffing of the earth wire/ OPGW during erection orcontinued operation. The clamp shall have smooth and permanent grip to keep theBird flight diverter in position on the earth wire/ OPGW without damaging the strands or causing premature fatigue failure of the earth wire/OPGW under the clamp. The clamp groove shall be in uniform contact with the earth wire/ OPGW over the entire clamping surface. The groove of the clamp body and clamp cap shall be smooth, free from projections, grit or materials which could cause damage to the earth wire/OPGW when the clamp is installed.
The Clamp shall have strong grip on earth wire/ OPGW. The clamp should not slip when pulled by a force of 0.25 KN in the direction parallel to earthwire/ OPGW the details/ properties of Earthwire /OPGW are mentioned in relevant section of Earth wire/OPGW of Technical specification. All exposed metal parts of clamp shall be corrosion free. The Clamp must be able to bear pulling load of minimum 100kg.
The supplier shall guarantee that there shall not be any failure/ breaking of bird flight diverters under normal operating condition. In the event of any failure/ breaking of bird flight diverters during the first five(05) years of service, supplier shall supply to the purchaser free of cost spare bird flight diverters equal to the failed bird flight diverters quantity.
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Placement of Bird Flight Diverter
BIRD FLIGHT DIVERTER SHOULD BE FIXED ON WHICH CONDUCTORS
CEA guidelines say that Bird Flight Diverters (BFD) are to be installed on all conductors including earth wire.
GUIDELINES - GAP BETWEEN BIRD FLIGHT DIVERTERS:
Max permissible gap between bird flight diverters on OPGW is 10 meters, whereas on conductors, gap can be increased to 15 meters.
DOUBLE CIRCUIT LINES: On double circuit lines, BFD may be fixed on 1st circuit between first two towers. Between next two towers, these may be fixed on circuit 2....and like wise.
COMPARISON of TECHNICAL SPECIFICATIONS of
M/s Power Grid Corporation of India Limited & M/s Central Electricity Authority (Govt. of India)
ESTIMATED TIME REQUIRED FOR TESTS AS PER M/s CEA GUIDELINES
Generally Suspended devices i.e Dynamic Bird Flight Diverters shall be used in the transmission line as bird diverters.
1.3.6.2.12.1 Suspended devices:-Dynamic Bird Flight Diverters
1.3.6.2.12.1.1 Warning Disc
Diameter of circular warning disk shall not be less than 150 mm. If warning disk is quadrilateral or trapezoid, then shortest arm length should not be less than 90 mm. Thickness of the warning disc shall not be less than 3 mm. Minimum reflective area on each face of warning disk shall not be less than 50 % of the entire area subject to minimum 4000 sq. mm. All suspension hardware which are directly exposed (moving or static) must be corrosion free. Bearing swivel shall be made of stainless steel and should allow free spinning in minimum wind speed of 2 km/hour.
1.3.6.2.12.1.2 Clamp
It shall be capable of supporting the Bird flight diverter during installation and prevent damage or chaffing of the earth wire/ OPGW during erection orcontinued operation. The clamp shall have smooth and permanent grip to keep theBird flight diverter in position on the earth wire/ OPGW without damaging the strands or causing premature fatigue failure of the earth wire/OPGW under the clamp. The clamp groove shall be in uniform contact with the earth wire/ OPGW over the entire clamping surface. The groove of the clamp body and clamp cap shall be smooth, free from projections, grit or materials which could cause damage to the earth wire/OPGW when the clamp is installed.
The Clamp shall have strong grip on earth wire/ OPGW. The clamp should not slip when pulled by a force of 0.25 KN in the direction parallel to earthwire/ OPGW the details/ properties of Earthwire /OPGW are mentioned in relevant section of Earth wire/OPGW of Technical specification. All exposed metal parts of clamp shall be corrosion free. The Clamp must be able to bear pulling load of minimum 100kg.
1.3.6.2.12.2