Non-LED Bird Flight Diverter (PLM/NLD-V1) — Robust Passive Protection with Zero Maintenance
Retroreflective daytime visibility. Glow-in-dark transitional light protection. 360° rotational motion. No battery. No electronics. 15-year design life.
★ CEA Compliant |Made in India | Model: PLM/NLD-V
What is the Non-LED Bird Flight Diverter?
The Prakritis Non-LED Bird Flight Diverter (model PLM/NLD-V1) is a fully passive, zero-maintenance avian collision mitigation device for installation on overhead transmission line conductors, earth wires, and sub-transmission cables. It provides effective bird collision prevention through three simultaneous passive mechanisms — dynamic rotational motion, retroreflective daytime visibility, and photoluminescent glow-in-dark performance at dawn and dusk — without any battery, electronics, or power source of any kind.
The PLM/NLD-V1 is the recommended standard-deployment diverter for transmission network operators seeking CEA-compliant, utility-approved avian protection across their line network with the lowest total cost of ownership. Its 15-year design life, 5-year warranty, and zero maintenance requirement make it the economically optimal choice for large-scale deployment on standard network sections where active illumination is not specifically mandated.
Bird Flight diverter on Power Lines
How the Non-LED Diverter Works
360° Rotation — Dynamic Visual Stimulus
A 360-degree rotating swivel allows the circular flapper to spin continuously in medium wind speeds, generating a persistent dynamic visual cue. Birds are neurologically predisposed to respond to motion — continuous rotation ensures the diverter remains conspicuous throughout daylight hours even as a bird's approach angle changes relative to the conductor.
Retroreflective Stickers — Passive Daytime Visibility
Two multicolour retroreflective stickers on each face of the warning disc provide a minimum retroreflective area of +5,500 mm² per face — exceeding the CEA minimum specification. Retroreflection returns incident light toward the approaching bird, making the diverter highly visible in direct sunlight and at low solar elevation angles — the lighting conditions that correlate with peak avian flight activity.
Glow-in-Dark Polymer Flapper — Dawn and Dusk Protection
The circular warning disc is manufactured from photoluminescent polymer providing a glow area of +12,000 mm² per face. During daylight, the material absorbs ambient light energy. At dusk and dawn — the periods of highest large-bird collision risk — the stored luminescence is released as visible glow, making the conductor detectable without any power source. Total surface area exceeds +25,000 mm², delivering an imposing visual target.
Pendulum Swing Joint — Aerodynamic Stability
A pendulum mechanism at the base of the clamp assembly restricts flapper swing to a controlled arc, preventing the erratic, unpredictable movement that can occur in high-speed wind. The pendulum provides consistent, stable visual behaviour across the full wind speed range — from calm to storm conditions.
Key Benefits of the Non-LED Diverter
- Zero maintenance — no battery replacement, no electronic servicing, no scheduled interventions over the 15-year service life
- Lowest total cost of ownership across the Prakritis product range — optimal for large-scale network-wide deployment
- Effective three-layer passive visibility: dynamic motion + retroreflection + photoluminescence across the full day
- Lightest device in the range (<350g) — minimal additional structural load on conductors
- No power source dependency — fully operational in remote, off-grid locations with no infrastructure support
- Eco-conscious materials — no battery chemistry, no electronic components, no end-of-life hazardous waste
- CEA-compliant and PGCIL/GETCO/RVPN approved — direct-submission procurement documentation available
- Universal clamp (5mm–38mm) — one SKU covers all conductor types across the entire network
Ideal Applications for the Non-LED Diverter
Primary Recommendation: Standard Transmission Network Deployment
The PLM/NLD-V1 is the standard deployment solution for transmission line sections where the avian collision risk profile is significant but does not require the active illumination capabilities of the LED model. It is the economically optimal choice for operators deploying diverters across large extents of their network as a systematic avian protection measure.
- Standard HV and EHV transmission line earth wires and overhead ground wires
- Sub-transmission overhead line conductors in peri-urban and rural areas
- New transmission line construction — specified as standard fitment in sections not classified as high-risk
- Network-wide retrofit programmes where CEA compliance is required across all line sections
- Lines adjacent to wildlife habitat where active illumination is not specifically mandated by environmental clearance
- Telecom tower guy wires and antenna support cables
- Wind farm inter-array overhead cable sections outside primary migratory crossing zones
Mixed Deployment Strategy
The PLM/NLD-V1 is commonly deployed alongside LED diverters in a risk-zoned line strategy: LED models at the highest-risk spans (wetland crossings, habitat corridors, documented mortality hotspots) and Non-LED models on the remaining lower-risk spans. This approach optimises ecological protection per unit procurement cost.
Installation Overview
Compatible Conductors
The universal clamp accommodates ACSR, AAAC, AAC, OPGW, and standard earth wire types with diameters from 5mm to 38mm. No adaptation hardware is required for any standard Indian transmission line conductor type.
Recommended Spacing
CEA guidelines specify installation spacing based on conductor height, bird species risk profile, and terrain context. The PLM/NLD-V1 is typically installed at every 5 to 15 metres on the topmost earth wire in designated protection zones. Our technical team provides project-specific spacing recommendations.
Installation Methods
- Manual installation on de-energised conductors — standard hand tools, no specialist equipment
- Hot-stick installation on live energised lines — no planned outage required for retrofit
- Simple 4-step installation: open clamp, position, tighten to torque, verify free rotation
Testing & Certification
The PLM/NLD-V1 is subjected to the full CEA type test programme:
- Mechanical Strength Test — clamp slip (±25kg) and pull (+100kg)
- Vibration Test — Aeolian vibration fatigue resistance
- Temperature Cycle Test — -20°C to +100°C dimensional stability
- Heating Cycle Test — thermal endurance
- Radio Interference Voltage (RIV) / Visual Corona Test — HV line EMC validation
- Corrosion Resistance Test — salt spray durability
- Accelerated Ageing Test — UV and weathering exposure for 15-year service life
- Visual Examination and Dimensional Inspection — CEA tolerance conformance
Engineering Design Principles
Circular Flapper Configuration
The 180mm diameter circular flapper design provides optimal visual profile while minimizing wind loading on conductor systems. Unlike traditional spiral designs, the circular configuration presents consistent visual signature from all approach angles, ensuring detection probability remains high regardless of bird flight direction.
The flapper mounts on a swing joint cap allowing pendulum movement that restricts excessive swing during high wind conditions. This controlled movement prevents jerky oscillations while maintaining gentle dynamic motion that attracts avian attention.
360-Degree Rotating Swivel
The central mounting incorporates a 360-degree rotating swivel enabling seamless rotation under wind force. This bearing-free rotation mechanism requires no maintenance throughout the product service life, as rotation occurs through wind interaction with the flapper surface rather than complex mechanical components.
Wind speeds as low as 10-15 km/h initiate rotation, ensuring dynamic movement during majority of operational hours across most geographical locations.
Glow-in-Dark Technology
Photoluminescent Polymer IntegrationTotal glow-in-dark area: 12,000mm² per face minimum.The glow-in-dark polymer absorbs solar radiation during daylight hours, storing energy within the material matrix. As ambient light decreases during twilight periods, the stored energy releases as visible light emission, creating self-illuminated markers without external power requirements.
This passive illumination extends visibility during dawn and dusk periods when many wetland bird species demonstrate peak flight activity, bridging the performance gap between purely passive markers and active LED systems.
Retro-Reflective Sticker System
Multicolor Retro-Reflective Surfaces
Total retro-reflective area: 5,500mm² per face minimum.Two multicolor retro-reflective stickers bond to each flapper face, incorporating engineered glass microsphere technology. When light from any source (sunlight, moonlight, aircraft landing lights) strikes the retro-reflective surface.Here's a reflector that reflects light back toward the source at higher intensity than surrounding surfaces.
Color Configuration:International orange sections for high daytime contrast
White sections for maximum luminance reflection
Yellow accent areas for additional visibility enhancement
The alternating color pattern creates visual modulation as the flapper rotates, generating temporal contrast that activates avian motion detection pathways.
Universal Clamp System
lamp diameter range: 5mm to 38mm
The universal-size clamp accommodates virtually all distribution and transmission conductor sizes through single design, eliminating need for multiple product variants based on conductor diameter. This universal compatibility simplifies procurement, inventory management, and field installation.
Clamp Material: UV-stabilized polymer matching flapper material properties Temperature range: -20°C to +100°C operational capability Hardware: All fasteners manufactured from non-corrosive stainless steel
Retention Performance:
Slip resistance: ±25kg minimum
Pull strength: +100kg minimum
These retention values ensure the bird flight diverter remains securely attached under maximum design wind loads, conductor galloping events, and ice loading conditions.
Avian Safety
Get Informed: Non-Led Diverters FAQ
What protection does the Non-LED diverter provide during complete darkness?
The photoluminescent glow-in-dark polymer flapper (+12,000 mm² per face) absorbs ambient light during the day and releases visible luminescence during dusk, dawn, and early night. For complete darkness protection throughout the night, we recommend the LED model (PLM/LD-V1), which provides active LED illumination. The Non-LED model is optimal where dawn/dusk protection is the primary concern and full nocturnal coverage is not required.
Does the Non-LED diverter require any servicing or maintenance?
The PLM/NLD-V1 is a fully passive device with no battery, electronics, or moving parts that require servicing. Routine visual inspection during scheduled line patrols is recommended to confirm clamp security and unobstructed flapper rotation. No scheduled maintenance interventions are required over the 15-year design life.
Is the Non-LED diverter sufficient for GIB habitat corridor deployments?
It depends on the specific project specification and regulatory mandate. For many GIB habitat corridor sections, a combination of LED diverters (at highest-risk spans) and Non-LED diverters (on adjacent standard-risk sections) is specified. Where active illumination is specifically mandated by the environmental clearance condition or utility specification, the LED model (PLM/LD-V1) is required. Our technical team can advise on the appropriate model split for your project.
Where Can Non-LED Bird Flight Diverters Be Installed?
These diverters can be installed on a variety of structures including power lines, communication towers, wind turbines, and other tall structures prone to bird collisions. They are particularly useful in areas with high bird activity or migratory routes
Can the Non-LED diverter be installed on live transmission lines?
Yes. The PLM/NLD-V1 supports hot-stick installation on energised conductors by trained live-line crews, eliminating the need for planned outages during retrofit deployments. Manual installation on de-energised lines is also fully supported.