sible for its content.
o te technical note technic a
Light Emitting Diode Taxiway
Lighting Effects on Constant
Current Regulator Stability




















May 2008

DOT/FAA/AR-TN08/29


This document is available to the U.S. public through the National
Technical Information Services (NTIS), Springfield, Virginia 22161.










U.S. Department of Transportation
Federal Aviation Administration


o
te technical note technic
a
NOTICE

This document is disseminated under the sponsorship of the U.S.
Department of Transportation in the interest of information exchange. The
United States Government assumes no liability for the contents or use
thereof. The United States Government does not endorse products or
manufacturers. Trade or manufacturer's names appear herein solely
because they are considered essential to the objective of this report. This
report does not constitute FAA certification policy. Consult your FAA
airports office as to its use.























This report is available at the Federal Aviation Administration William J.
Hughes Technical Centers Full-Text Technical Reports page:
actlibrary.tc.faa.gov in Adobe Acrobat portable document format (PDF).



Technical Report Documentation Page
1. Report No.


DOT/FAA/AR-TN08/29
2. Government Accession No.

3. Recipient's Catalog No.

5. Report Date


May 2008

4. Title and Subtitle

LIGHT EMITTING DIODE TAXIWAY LIGHTING EFFECTS ON
CONSTANT CURRENT REGULATOR STABILITY

6. Performing Organization Code


7. Author(s)


Holly M. Cyrus and Jess Nadel*
8. Performing Organization Report No.


9. Performing Organization Name and Address


Federal Aviation Administration

*Hi-Tec Systems, Inc.
William J. Hughes Technical Center
500 Scarborough Drive
10. Work Unit No. (TRAIS)

Airport and Aircraft Safety

Suite 108
Research and Development Division
Egg Harbor Township, NJ 08234
Airport Technology Research and
Development Branch
Atlantic City International Airport, NJ 08405

11. Contract or Grant No.



12. Sponsoring Agency Name and Address

U.S. Department of Transportation
Federal Aviation Administration
Office of Airport Safety & Standards
Washington, DC 20591
13. Type of Report and Period Covered

Technical Note

14. Sponsoring Agency Code

AAS-100
15. Supplementary Notes

Paul Jones and Donald Gallagher of the FAA William J. Hughes Technical Center and Jim McGonigle of Consultant Services
International, Inc. provided technical support throughout the course of the evaluation.
16. Abstract

This study was conducted to determine how light emitting diode (LED) taxiway edge lights affect the operation of Constant
Current Regulators (CCR). Some CCRs turn off due to overvoltage or overcurrent because of LED taxiway edge lights.

A test bed was developed to measure and record the voltage and current supplied to an LED taxiway edge fixture as power was
applied. The test bed setup consisted of an LED taxiway edge fixture, circuit current control subsystem for constant current to
the taxiway edge fixture, and a data acquisition subsystem, which collected the data for analysis. Five types of LED taxiway
edge fixtures were used for the testing.

The baseline incandescent taxiway edge fixture had a smooth power curve. Two of the five LED taxiway edge light fixtures
showed significant peak power volt ampere (VA) loading after power-up compared to the loading during normal operation. The
highest peak power VA was 163% of the nominal VA required.

Based on the results of this study, the following are recommendations for future operation of LED taxiway edge lighting fixtures.


The peak power VA required by an LED taxiway edge lighting fixture should not exceed the nominal operating power
VA by more than 10% for the fixture. When the peak load is limited to 10%, the CCR will have enough reserve capacity
to support the load and should easily adjust so that it will not trip off due to an overvoltage condition.


The LED taxiway edge light fixture should not drop the power VA required at a given step by more than 10%. When the
power VA load suddenly drops, the CCR can trip off due to overcurrent. By limiting the power VA drop to 10%, the
overcurrent protection function of the CCR should easily adjust so that it will not trip off due to an overcurrent
condition.

17. Key Words

Light emitting diode, Constant Current Regulator, CCR
Stability
18. Distribution Statement

This document is available to the U.S. public through the
National Technical Information Service (NTIS),
Springfield, VA 22161.
19. Security Classif. (of this report)

Unclassified
20. Security Classif. (of this page)

Unclassified
21. No. of Pages


20
22. Price


Form DOT F 1700.7
(8-72)

Reproduction of completed page authorized

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY
vii

INTRODUCTION 1

Purpose
1
Background 1
Scope
1
Objectives 1
Related Documents
2

DISCUSSION
2

EVALUATION APPROACH
3

Test Setup
3
Circuit Current Control
3
Data Acquisition
3

COMPARATIVE RESULTS
4

Incandescent Baseline
4
Fixture 1
4
Fixture 2
4
Fixture 3
4
Fixture 4
5
Fixture 5
5

SUMMARY
5

CONCLUSIONS 6

RECOMMENDATIONS 7

iii
LIST OF FIGURES

Figure

Page

1
Diagram of the Project Test Setup
8
2
Circuit Control Screen
8
3
Baseline Incandescent Apparent Power and Resistance
9
4
Fixture 1 Apparent Power and Resistance
9
5
Fixture 2 Apparent Power and Resistance
10
6
Fixture 3 Apparent Power and Resistance
10
7
Fixture 4 Apparent Power and Resistance
11
8
Fixture 5 Apparent Power and Resistance
11
9
Longer View of Fixture 5 Apparent Power and Resistance
12

iv
LIST OF TABLES

Table
Page

1
Summary of Power Characteristics
5
2
Fixture 3 Circuit VA Load, 250 Fixture Example
6
v
vi
LIST OF ACRONYMS

AC Advisory
Circular
CCR
Constant Current Regulator
EUT
Equipment under test
FAA
Federal Aviation Administration
Hz Hertz
LED
Light emitting diode
NI National
Instruments
RMS
Root mean squared
V Volt
VA Volt
ampere

EXECUTIVE SUMMARY

This study was conducted to determine how light emitting diode (LED) taxiway edge lights
affect the operation of Constant Current Regulators (CCR). Some CCRs turn off due to
overvoltage or overcurrent of LED taxiway edge lights.

A test bed was developed to measure and record the voltage and current supplied to an LED
taxiway edge fixture as power was applied. The test bed setup consisted of an LED taxiway
edge fixture, a circuit current control subsystem for constant current to the taxiway edge fixture,
and a data acquisition subsystem, which collected the data for analysis. Five types of LED
taxiway edge fixtures were used for the testing.

The baseline incandescent taxiway edge fixture had a smooth power curve. Two of the five LED
taxiway edge light fixtures showed significant peak power volt ampere (VA) loading after
power-up compared to the loading during normal operation. The highest peak power VA was
163% of the nominal VA required.

Based on the results of this study, the following are recommendations for future operation of
LED taxiway edge lighting fixtures.



The peak power VA required by an LED taxiway edge lighting fixture should not exceed
the nominal operating power VA by more than 10% for the fixture. When the peak load
is limited to 10%, the CCR will have enough reserve capacity to support the load and
should easily adjust so that it will not trip off due to an overvoltage condition.



The LED taxiway edge light fixture should not drop the power VA required at a given
step by more than 10%. When the power VA load suddenly drops, the CCR can trip off
due to overcurrent. By limiting the power VA drop to 10%, the overcurrent protection
function of the CCR should easily adjust so that it will not trip off due to an overcurrent
condition.




vii/viii
INTRODUCTION

PURPOSE.

The Federal Aviation Administration (FAA) Office of Aviation Research Airport Safety
Technology Research and Development Section (AJP-6311), in response to a request from the
Airport Engineering Division (AAS-100), undertook this project to evaluate how the use of light
emitting diode (LED) technology for airport lighting circuits impacts Constant Current Regulator
(CCR) operation. This research will assist in the revision of Advisory Circulars (AC)
concerning LED fixtures and CCRs.

The purpose of this research is to characterize and investigate the electrical characteristics of
LED fixtures that relate to overall performance and compatibility of these products with the
existing airfield infrastructure. During this investigation, the electrical behavior of LED fixtures
provided an unusual load to an airfield lighting circuit that could cause improper