Corona Testing of Devices Used to Mitigate Bird Collisions

Publication Number: 500-04-086F
Publication Date: September 2004

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Executive Summary

Introduction

One of the most effective ways to reduce avian collisions with power lines is to mark wires, making them more visible. Although several products are available to mark lines, there can be engineering/maintenance issues associated with placing these devices on energized wires. Corona discharge is one of the issues associated with using the marking devices. These discharges occur when surface electric field intensity surrounding an energized electrode exceeds a critical value, resulting in a localized ionization of the surrounding gas - in most cases, air. Corona activity generates light (mainly in the UV spectrum), sound waves, electromagnetic radiation, ozone, and other by-products that can result in unacceptable audio noise (AN) and/or radio interference (RI). Corona activity may occur from sharp edges on energized hardware, broken conductor strands, or defective insulators.

Purpose

The purpose of this project was to determine whether various marking products could be used on energized wires (at different voltages) without creating significant corona discharge.

Project Objective

The objective of this project was to test a variety of flight diverter devices at simulated 115-kV, 230-kV, and 345kV phase-to-phase line voltages, to measure the corona produced by each device.

Project Outcomes

The best-performing devices at 115 kilovolts (kV) were the Bird Flight Diverter and the Swan Flight Diverter, neither of which had any detectable corona discharge. At 230 kV, the Swan Flight Diverter and the Bird Flight Diverter had a medium level of corona, but still outperformed the flapper-type diverters. At 345 kV, all the devices had very high levels of corona.

Conclusions

Below 115 kV, all of the devices are suitable from an AN and RI perspective.

Recommendations

The levels of AN and RI generated by the devices above voltages of 115 kV do not invalidate their use at these voltages. Rather, device installations should be in areas that will not elicit complaints of the resulting AN and RI. Material degradation may occur at 115 kV and higher, resulting in premature failure. Utilities should have sufficient test data to know if the proposed device can withstand the long-term effects of corona at 115 kV and higher.

Benefits to California

This results of this research will enable biologists and engineers to determine on which voltages they can install flight diverters without creating excessive AN or RI. As a result, flight diversion efforts can proceed without concerns about these impacts, thereby removing a potential barrier to the use of these devices.

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Abstract

Bird deaths resulting from power line collisions are a violation of the Migratory Bird Treaty Act and can result in federal fines. Accordingly, utilities often mark wires with various devices in bird concentration areas to prevent such collisions.

Placing such devices on energized power lines can reduce avian collisions with those lines; however, one of the issues associated with marking devices is corona discharge. Corona activity on power lines can result in audio noise (AN) or radio interference (RI) complaints. Because corona may result in customer complaints, it is important to know how marking wires might influence corona. This information will give biologists and engineers the information they need to determine the voltage of wires they can mark without creating unacceptable levels of AN or RI.

Below 115 kilovolts (kV), all of the devices are suitable from an AN and RI perspective. The best-performing devices at 115 kV were the Bird Flight Diverter and the Swan Flight Diverter, neither of which had any detectable corona discharge. At 230 kV, the Swan Flight Diverter and the Bird Flight Diverter had a medium level of corona, but still outperformed the flapper-type diverters. At 345 kV, all the devices had very high levels of corona.

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Table of Contents

Preface

Abstract

Executive Summary

1.0 Introduction

2.0 Project Approach

3.0 Project Outcome

4.0 Conclusions

List of Figures

Figure 1. Flight diverters tested as part of the project
Figure 2. Test setup
Figure 3. DayCor II camera
Figure 4. DayCor II camera
Figure 5. Bird Strike Indicator
Figure 6. Bird Flight Diverter, Tyco Electronics (BFD2460)
Figure 7. Swan Flight diverter, Tyco Electronics (SFD1960)
Figure 8. Bird Flapper, Mission Environmental
Figure 9. Bird Diverter, Bird Safe
Figure 10. Bird Flapper - Prototype, Mission Environmental
Figure 11. Bird Flapper, Preformed Line Products (LSFB0416)
Figure 12. Bird Flapper, Preformed Line Products (FB0515)
Figure 13. Bird Mark, P&R Technologies
Figure 14. Bird Flapper - Prototype, Midsun Group
Figure 15. Firefly Bird Flapper, P&R Technologies
Figure 16. Level 0: No corona
Figure 17. Level 1: Barely detectible corona
Figure 18. Level 2: Definitely detectable corona (at bottom of cable clamp)
Figure 19. Level 3: Medium level of corona
Figure 20. Level 4: High level of corona
Figure 21. Level 5: Very high level of corona
Figure 22. Corona-induced damage on diverter #5

List of Tables

Table 1. List of flight diverter manufacturers and models tested
Table 2. System voltages and corresponding test voltages
Table 3. Corona levels for all the devices tested