NATIONAL BUREAU OF STANDARDS REPORT

3830

ISOCANDLE DISTRIBUTION AND LIFE OF

PREPRODUCTION 100-PAR56 LAMP

FOR LEAD-IN SYSTEMS

By

R. ¥. Crouch

<NBS>

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

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in specialized research, development, and engineering in the field indicated by its title. A brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance and Reactance Measurements. Electrical Instruments. Magnetic

Measurements. Electrochemistry.

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Services. Frequency Utilization Research. Tropospheric Propagation Research. High Frequency

Standards. Microwave Standards.

©Office of Basic Instrumentation ©Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0201-20-2303 3830

ISOCANDLE DISTRIBUTION AND LIFE OF

PREPRODUCTION 100-PAR36 LAMP

FOR LEAD-IN SYSTEMS

Prepared by

R. W. Crouch

Photometry and Colorimetry Section

Optics and Metrology Di-vision

Test 21A-12/5U

Tested for

Airways Engineering Division

Civil Aeronautics Administration

Washington 2£, D. C.

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, reprlntl

unless permission Is obta

25, D.C, Such permissl

cal ly prepared If that a

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

irt, Is prohibited

rds, Washington

has been speclfifor Its own use.

ISOCANDLE DISTRIBUTION AND LIFE OF PREPRODUCTION 100-PAR56 LAMP

FOR LEAD-IN SYSTEMS

By R. W. Crouch

1.

SCOPE

This report shows the isocandle distribution of three samples of

a new 100-PAR56 lamp and the results of life-testing these samples.

2.

LAMPS TESTED

The lamps tested are preproduction samples of a new lamp developed

by the General Electric Company for the Airways Engineering Division of

the Office of Federal Airways, They are marked on the back, "General

ELectric / 100 W - 119 V / Airport Approach", together with the numbers

" 1 ", "I4 ", and " 8 " written in grease pencil to distinguish them from

each other.

These lamps were specified by the Airways Engineering Division to

have bulbs consisting of standard PAR96 reflectors, cover-lenses of the

type used on the Navy 399-PAR lamps, and a power consumption of 100

watts at 11£ volts. The voltage and power consumption x^ere selected to

meet the requirements of the CAA "lead-in" systems.

3.

TEST PROCEDURE

To provide measured horizontal and vertical rotations of the test

lamps, they were mounted in a special fixture on the table of a goniometer.

The primary axis of rotation was horizontal and normal to the photometric

axis. The line perpendicular to the vertical plane of the fixture at the

center of the lamp aperture was taken as the axis of the lamp. The

angles of the goniometer corresponding to this axis were determined by

clamping a tube sight to the fixture so that the optical axis of the

sight and the lamp axis were collinear. The goniometer was then rotated

to make the optical axis of the tube sight and the photometric axis

collinear and the horizontal and vertical angles of the goniometer were

recorded as horizontal and vertical angles of reference (0°). The isocandle curves have been plotted with the axis of the lamp at the origin

of coordinates.

The candlepower distribution was measured with an automatic photometer, the recording element of which was a Leeds & Northrup recording

potentiometer driven in synchronism with the goniometer on which the lamp

under test was mounted. The photometer was calibrated with standard lamp

No. BS 3319 at a distance of 1.9 meters; the photometric distance was 30.0 meters ( 98 .I4 feet).
-

'

.

:

; ' .. .

.

.

- "

. ;V-: • >. ";i

%

-
2-

When the calibration adjustment x^as completed, a record was made

on the candlepower distribution chart. In figures 1, 2, and 3 these

records have been marked to show the test lamp candlepower which would

be equivalent at the photocell to that of the standard lamp.

All photometric measurements were made with a 60-cycle, constantvoltage, source adjusted to give 115 volts between the test-lamp

terminals. Since total lumen ratings are not available for preproduction lamps, no correction factors were introduced for the lumen output

of the test lamps. The life of the three lamps was obtained by connecting them to a 60-cycle pox-rer source regulated to 115 volts, within

±0.2$. Throughout life they were inspected at intervals and the results

quoted are within ±8 hours.

U. RESULTS

The vertical candlepower distribution curves in figures 1, 2, and

3 show a peak candlepower of approximately I4.5 kilocandles for each

lamp. The double line, which appears in some parts of the distribution curves of figures 1, 2, and 3> resulted from repeating the measurements after the lamps had been in operation for approximately one- half

hour in each case. During this time, additional horizontal distribution

curves were made from which isocandle curves were plotted and drawn. The

distribution of candlepower as shown by the curves in figures i|, 5* and 6

is remarkably free from the irregularities which are usually found in

curves of this type. These figures also show the specified minimum values.

The electrical characteristics, as determined during the candlepower measurements, and the life are shown in the following table.

Table I

Lamp No. Life

Hours

Voltage (Set)

Volts

Current

Amperes

Watts

(Computed)

1 558 115 .905 ioU

h 6^8 n5 .908 lOii

8 75U n5 .905 ioU

In the absence of a total-lumen rating, an estimate of the candlepower for an average lamp of the type tested can be made from the nominal

-3-

and actual wattage of the lamps. The test lamps were operated at

10h% of their rated power. Using this value, 10k%, and the formula*-,

operating lumens _ operating watts 2,1 ^ rated lumens rated watts )

it is estimated that an average lamp of this type operating at 100

watts may be expected to have a candlepower in the indicated directions equal to the values shown on the isocandle curves decreased

by the factor 0.92.

*T.E. S. Handbook ( 2nd Ed.) 8-lU.

9 . CONCLUSIONS

From the curves in figures I4, 5>, and 6 and the values stated in

Table I for -the life, the lamps tested are found to be in accordance

with the requirements for lead-in lights as communicated to this

Bureau by the Office of Federal Airways, C.A.A.

LAMP FOR LEAD-IN SXSTEM

HORIZONTAL AND VERTICAL CANDLEPOWER DISTRIBUTIONS

*

. as recorded fay photometer

Lamp No. 1

LAMP 100-PAR

Bulb: PAR 56

Lens: Type 399 PAR 56

Rated: 100 Watts, 115 Volts-

.

. \

5 Kilocandles

Calibration

375Tkc~

NBS Test 21A-12/5U

_I L_ -J.

t

i Figure 1

v n»>4

Cayj&iJfciao.

3-68 KC

LAMP FOR LEAD-IR SYSTEM

HORIZONTAL AND VERTICAL CABEfLEPOWIH DISTRIBUTIONS

a8 recorded by photometer

Leap No. It

LAMP 100-PAR

Bulb: PAR 56

Lene: Type 399 PAR 56

Rated* 100 Watts, 115 Volts

5 Kiloeandlee

0

30* 20* L ,

i

•

MBS Test 2U-12/51* Flifure 2

I l._L_

V ON

LAMP FOR IEAD-IN SYSTEM

HORIZONTAL AND VERTICAL CANDLEPOWER DISTRIBUTIONS

as recorded by photometer

] Lamp No. 8

Lamp: 100-PAR

Bulb: PAR 56

Lens: Typ* 399 PAR 56

Ratad: 100 Watts, 115 Volts

> : .. __ Li ...• .

[ t

1

:

.

5 Rllocandles -

; / ;

.

r

; P'

"

• :

. f- [

- i f

- -

.

Calibration

3.68 KC

* .i Mu l *Ut

>





THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

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problems; invention and development of devices to serve special needs of the Government; and the

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Commission. The scope of activities is suggested by the listing of divisions and sections on the

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publications should be addressed to the Office of Scientific Publications, National Bureau of

Standards, Washington 25, D. C.
NBS