NATIONAL BUREAU OF STANDARDS REPORT

4463

Current-Intensity, Voltage-Intensity, and Current-Voltage

Characteristics of Runway- and Approach-Light Lamps

By

Photometry and Colorimetry Section

Optics and Metrology Division

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0201-20-2301

0201-20-2331

December 30, 1955 4463

Current-Intensity, Voltage-Intensity, and Current-Voltage

Characteristics of Runway- and Approach-Light Lamps

By

Photometry and Colorimetry Section

Optics and Metrology Division

Prepared For

Visual Landing Aids Branch

Airborne Equipment Division

Department of the Navy

and

Equipment Laboratory

Wright Air Development Center

Department of the Air Force

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, reprinting

unless permission Is obtaine 25 , D . C . Such permission

cally prepared if that agei

Approved for public release by the

director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

is prohibited Washington

been specifi- cs own use.
d1 '
4463

Report on the

Current-Intensity, Voltage-Intensity, and Current-Voltage

Characteristics of Runway- and Approach-Light Lamps

Abstract

This report is a compilation of measurements of the intensity

current-voltage characteristics of lamps of the types generally

used in approach-, runway-, and taxiway-lighting systems. The

results of a study of the effects of color filters on the relative

intensity of the lamps are includedo

1. INTRODUCTION

Intensity control is now used on nearly all runway- and approach-light systems and is being considered for taxiway-light

systems. The increasing complexity of the problems of intensity

control has increased the need for information on the relative

intensity characteristics of lamps used in approach, runway, and

taxiway lighting as a function of the applied current or voltage.

In addition, information on the effect of color filters upon the

relative intensity is needed. This report was prepared to meet

this need.

Relative intensity is defined as the ratio in percent of the

intensity of a lighting unit or lamp operated at a stated current

or voltage to the intensity of the same unit or lamp operated at

rated current or voltage. Note that in obtaining the relative

intensity of a colored light, measurements of the intensity at

both the stated current (or voltage) and the rated current (or

voltage) are made with the color filter in place. Thus, the trans

mittanee of the filter has only a second-order effect on the relative intensity.

2. METHOD OF MEASUREMENT

Measurements of relative intensity were made using a colorcorrected barrier-layer photocell in a zero-resistance circuit.

The response of this photometric system was checked. No significant deviations from linearity were found, ^hen reflector-type

lamps were tested, the center of the beam was directed at the

photocell. The relative intensities of lamps other than the

reflector type (325-lumen, 200-watt, T-14, etc.) were obtained by

measuring the relative horizontal intensity in a given direction.

Previous tests have shown that the relative intensity of clear
V
units in which these lamps are used does not differ significantly

from the relative horizontal intensity of the lamp used* Voltage

and current measurements were corrected for losses in the measuring

circuits, Whenever possible several lamps of a given type were

used. The results of the measurements of individual lamps were

averaged.

3, LAMP CHARACTERISTICS

For convenience in use, the characteristics of each lamp

(except for the 250-watt lamps) are given as three curves, a, relative intensity-current; b, relative intensity-voltage; and c, voltage-current. Curves for lamps with similar characteristics have

been grouped on the same figures. The lamp types studied and the

figures showing their characteristics are listed in table I.

Table I

Lamp Type

325-lumen, 6.6-ampere, airport marker

1020-lumen, 6, 6-ampere, airport marker

30-watt, 60 6-ampere, airport marker

45-watt, 6.6-ampere, airport marker

200-watt, 6.6-ampere, T-14, airport marker

200-watt, 6.6-ampere, PAR56, airport approach

500-watt, 6.6-ampere, T-20, airport marker

500-watt, 20-ampere, T-20, airport approach

250-watt, 12.5-volt, T-10, airport approach

250-watt, 12.5-volt, PAR56, airport approach

300-watt, 25-volt, PAR5 6, airport approach

350-watt, 25-volt, PAR56, airport approach

399-watt, 115-volt, PAR56, airport approach

500-watt, 120-volt, T-20, airport approach

may become large when the relative intensity becomes less than 1%.

The relative intensities may differ by as much as a factor of 2

when the relative intensity is about 0.2%.

Designation Figure

325/66/A21 la, b, and c 1020/66/A21 la, b, and c 6.6A/T10/1P la, b, and c 6. 6/T10P la, b, and c

6. 6A/T14P 2a, b, and c 6.6A/PAR56/2 2a, b, and c 6.6A/T20P 3a, b, and c 20A/T20/5 4a,be and c 20A/T10/P 5

2 50 PAR 5

— — 6a, b, and c 3 50 PAS 6a, b, and c 3 99 PAR 7a, b, and c 500T20/25 Ta, b, and c

i lamps of the same type

4. EFFECTS OF COLOR FILTERS

Because the transmittance of color filters is a function of the

color temperature of the source, the relative intensity characteristics of colored lights will differ from those of similar lights

-3-

which are "white”. The determination and presentation of the relative intensity characteristics of each type of lamp for each

aviation color would be unduly expensive. Therefore, a study was

made to determine representative correction curves, in case the use

of these curves proved feasible. Relative intensity characteristics

were determined for several of the types of lamps listed in table I in combination with filters representative of the limits of the

aviation colors. It was found that the data were adequately

represented by the lines plotted on figure 8. These lines siiow

the relative intensity of lights meeting the specification requirements for aviation colors as a function of the relative intensity

of the same light used without a filter. The lines are representative of "average" filters. The relative intensity of lights

with filters near the specification limits may differ from that

indicated by the lines by about ten percent at the lowest relative

intensities shown. The difference will, of course, be less at

higher relative intensities.

5. DISCUSSION

Differences in the change of relative intensity with change in

current or voltage for different lamps are significantly large so that generalized lamp-characteristic exponents cannot be satisfactorily used for all lamp types when the relative intensity is

varied over a wide range.

For lamps with the same rated current and of similar design

wattage (within 25%), the relative intensity-current characteristics are similar. See the curves on figure la. Also compare

the curves for the 200-watt, 6.6-ampere lamps, figure 2a, with

those of the 500-watt, 6. 6-ampere lamp, figure 3a„ The data

shown on figures 6b and 7b indicate that relative intensityvoltage characteristics are similar for lamps of similar design

wattage.

The data shown on figures 2a and 5 indicate that the characteristics of reflector-type lamps are not significantly different

from other lamp types of the same rated wattage and voltage.

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THE NATIONAL BUREAU OF STANDARDS

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