NATIONAL BUREAU OF STANDARDS REPORT

4441

PERFORMANCE CHARACTERISTICS

OF

THREE WASHINGTON STATE COLLEGE

NEON OBSTRUCTION LIGHTS

by

Robert T. Vaughan

to

Airways Engineering Division

Office of Federal Airways

Civil Aeronautics Administration

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

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0201-30-2328 December, 1955 4441

PERFORMANCE CHARACTERISTICS

OF

THREE WASHINGTON STATE COLLEGE

NEON OBSTRUCTION LIGHTS

by

Robert T. Vaughan

Photometry and Colorimetry Section

Optics and Metrology Division

NBS Test No. 21A-2/55

to

Airways Engineering Division

Office of Federal Airways

Civil Aeronautics Administration

Department of Commerce

<^BS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, r Approved for public release by the

r ^„ probiblleil

unless permission director Of the National Institute of

itandards, Washington

25,d.c. Such pe Standards and Technology (NIST) eport has been specifically prepared If On October 9, 2015 report for its own use.

Performance Characteristics

of

Three Washington State College

Neon Obstruction Lights

by

Robert T, Vaughan

1. SCOPE

This report presents the results of a study of the

candlepower and color characteristics of three neon

obstruction lights developed at the State College of

Washington,, Two of these are designed for use on the

catenaries of transmission lines,, The third is operated

by low voltage power.

Calculations of the visual range of the largest unit

were verified by observations in clear weather,

2 o DESCRIPTION OF UNITS TESTED

The units tested are samples of three lamps developed

in the laboratories of the Division of Industrial Research

at the State College of Washington. Two are identified by

nameplates bearing the legend:

“Catenary Obstruction Light

State College of Washington

Pullman, Wash. 11* No identifying marking was found on the third unit.

Figures I and II show the large catenary unit; Figure

III shows the small catenary unit at the top with the low

voltage unit below it. The large catenary unit was accompanied by two sheets of typewritten description and data.

The third unit was accompanied by a brochure describing it

as a “Model 300 Neon Obstruction Light**,

Each of the two catenary units consists essentially

of a cylindrical framework containing a neon lamp and supporting a specially designed transformer. Each of these

units is designed to be suspended on a transmission line

which passes along the axis of the unit thereby acting as

the one -turn primary of the transformer.

In the large unit there is a second lamp which serves

as a “stand-by11 and operates in event the service lamp fails.

The neon tubing of this unit is approximately 9 feet in

length and 9/lo inches in outside diameter. The transformer
.

‘ ’* IT. C'. ‘.j/;

'

-
- 2 -

of the large unit consists of a laminated core housed

in the rectangular case shown on the nearer end of the

unit in Figure II, The secondary is the large coil,

imbedded in what is described as epoxy waterproof resin,

which surrounds the lower horizontal side of the core,

The smaller coil on the rear vertical side of the core is

a special auxiliary primary provided for the purpose of

energizing the secondary under circumstances in which it

would not be practicable to simulate a transmission line

currento A production unit would not be supplied with

this coil. To facilitate the installation of this unit

the core is made with a gate which may be opened to admit

the transmission line without parting the line. A motor

driven trolley may be used to push the unit into position

on the span and clamp it to the line. It was assumed that

the side of the transformer core on which the secondary is

wound, being the heavier, would be located, in service,

directly beneath the line. The bar which passes through

the center of the unit as shown in Figures I and II simulates the transmission line.

In the small unit, shown in Figure III, the neon

tubing is approximately 5 1/2 feet in length and 1/2 inches

jn outside diameter. The transformer is made in four sections, two at each end of the unit. Each of these sections

presumably contains a core and a secondary winding encased

in a compound which is apparently the same as that used on

the secondary of the large unit. The secondary windings

are connected in series to supply the voltage necessary

for the operation of the lamp. For the installation of

this unit, the transmission line must be parted and threaded

through a tube along the axis of the unit.

The low voltage unit, “Model 300“, shown in Figure III

contains a helical neon tube similar to that used in the

small catenary unit. The brochure specifies that the unit

will operate satisfactorily on voltages ranging from 135

volts to somewhat below 90 volts.

3. RELATIVE CANDLEPOWER AS A FUNCTION OF LINE CURRENT

It was not practicable to simulate a transmission line

current while making candlepower distribution measurements

on the large catenary unit. For this reason a separate

laboratory procedure was used to measure the relative

candlepower of each lamp, in turn, at a fixed distance and

direction from the unit as a function of the current passing

through an aluminum bar running axially through the unit.

This bar was 8 feet in length and 1 1/4 inches in diameter.
. ..

*; I . j, I . .
- 3

-

To distinguish between the two lamps of the large

catenary unit, the lamp further from the transmission line

(see Figure II) has been designated as lamp “A11

, the nearer

one as lamp MB*. To distinguish between the two sides of

the unit, the term ^unobstructed side 59 is used when the lamps

are between the observer and the transmission line, and the

term “obstructed side 19 indicates that the transmission line

is between the observer and the lamps

.

With both lamps connected across the secondary of the

transformer, lamp did not operate . The minimum simulated

transmission line current at which lamp would operate

without “exce ssive3* flicker was approximately 62 amperes

,

The criterion for ^excessive 11 flicker was that flicker which

made photometric measurements impracticable., In order for

lamp WB

W to operate it was necessary to interrupt the connecting leads between lamp tt A

ts and the transformer. The

minimum simulated transmission line current at which lamp

*B“ would then operate without ”excessive“ flicker was approximately 65 amperes. In order to measure lamps WA

S* and WB“

under similar conditions, lamp ”Aa was remeasured, this time

with lamp **B W removed from the secondary of the transformer.

Under these conditions lamp nAn operated without “excessive*

flicker at a minimum line current of approximately 48 amperes

as compared with 62 amperes when both lamps were connected

across the secondary of the transformer.

4. CANDLEPOWER DISTRIBUTION OF UNITS

To provide measured horizontal and vertical rotations

of the test lamps, the units were mounted in special fixtures

on the table of a goniometer. The primary axis of rotation

was horizontal and normal to the photometric axis.

It was not practicable to mount the large catenary unit

with its axis horizontal, as in service. It was, therefore,

mounted with its axis coincident with the secondary axis of

the goniometer. With the goniometer at its *0.0* position,

this axis is vertical. The transformer end of the unit was

mounted uppermost, and the transmission line was represented

by a steel bar 1-5/8 inches in diameter running the full

length of the supporting framework. During the candlepower

distribution measurements, the special auxiliary coil was

used to operate the lamps at the intensity which would be

produced by a transmission line current of 1000 amperes. To

do this the photocell and meter which had been used for the

relative candlepower measurements was set up with the cell

at the same distance and direction from the test unit at which

it had been used previously. The current in the auxiliary

coil on the transformer of the test unit was then adjusted to

give the photometric reading indicated by the previous measurements extrapolated to 1000 amperes.
Ifi r ^ j|| i '
- 4 -

The measurements were made with an automatic photometer,

the recording element of which is a Leeds & Northrup recording potentiometer driven in synchronism with the goniometer

table on which the unit under test was mounted. The photometric distance was 10.0 meters.

The photometer was calibrated with standard filter No.

3639 and with standard lamp No. NBS6794 at a distance of

2.0 meters. The calibration has been recorded on the candlepower distribution chart as a line showing the candlepower of

the test unit which would give an illumination at the photocell equivalent to that given by the standard lamp.

The candlepower distribution charts, Figures 1 to 4,

show, for the large unit, a peak of approximately 73 candles

for lamp and 95 candles for lamp **B 41 on the unobstructed

side of the unit. On the obstructed side the peak was 51

candles for lamp “A11 and 65 candles for lamp liB

H

. It should

be noted that the candlepower on the obstructed side of the

unit depends somewhat on the diameter of the transmission

line, in this case a bar 1=5/8 inches in diameter.

Following the measurements on the large unit, the small

catenary unit was mounted in a special fixture on the table

of the goniometer with the axis of the unit on the primary

axis of rotation. The element of the cage which carries

the connecting leads between the sections of the transformer

was located directly under the lamp. The energizing current

of 150 amperes was passed through an aluminum bar, simulating a transmission line, which ran axially through the unit.

The photometer was recalibrated, and measurements were made

as before.

The minimum simulated transmission line current at

which the lamp would operate without ^excessive*4 flicker

was approximately 57 amperes. The candlepower distribution

charts, Figures 5 to 8, show a peak 01 32 candles.

A similar procedure was followed in making the measurements on the Model 3C0 unit. This unit was mounted on

the table of the goniometer with its axis on the secondary

axis of rotation, and power was supplied to it from a

regulated, 117-volt source. The candlepower distribution

charts, Figures 9 to 11, show relatively little change in

candlepower as a function of horizontal angle; the candlepower ranging between a minimum of 31 and a maximum of 38

candles on a 3&0C horizontal traverse.
.

1 ill

'

:
- 5 -

5. COLOR COMPARISONS

Using a L amine r-Brodhun photometer head, trained

observers compared the chromaticity of the light from

each test unit with that transmitted from a standard

lamp at 2350°K through a standard filter whose

chromaticity coordinates for light of that color temperature are known. In the case of each of the two catenary

units the comparisons were made at simulated rated

maximum transmission line current and at the minimum

simulated transmission line current at which the lamp

would operate without ^excessive 1 * flicker. The comparisons on the Model 300 unit were made with the unit operating from a regulated 117-volt source.

The color of all three units was found to be within

the limits prescribed for aviation red as defined in

specifications AN-C-56, Fed. Std. No. 3? and MIL-C-25050

(ASG) o 6. PERFORMANCE CHARACTERISTICS

The variation in the candlepower of the large catenary

unit as a function of the simulated transmission line current is shown in Figure 12. These curves were plotted

using the relative candlepower values of Section 3 and

values taken, from the curves of Figure _l. The curves of

Figure 12 show that the candlepower of the unit is very

nearly a linear function of the transmission line current,

varying from about 3 candles to 70 candles for lamp nA

n

and from about 2-1/2 candles to 5b candles for lamp nB

ik as the transmission line current increases from about 60

amperes to 1000 amperes. At 1000 amperes the candlepower

of lamp ttB

u is approximately 20$ less than that of lamp

lfc Afcl in the direction of measurement.

As shown in Figure 1, the peak candlepower of the

large unit is approximately 95 candles; enough for a

point source to be visible at 0.3 mile in the daytime,

assuming a threshold of visibility in daylight of about

1000 mile -candle s. Making allowance for the 2 5- inch

length of the light source, it was established that the

lamp at a distance of 1000 feet should be nearing the limit

of its visual range on a reasonably clear day.

The unit was mounted on an outdoor range and observed

against a sky background in the daytime from a distance of

approximately 1000 feet at a time when the visual range was

about six miles. The ring of the goniometer on which the

- 6 -

lamp was mounted was clearly visible, as was a strip

of black cloth about 2-1/2 inches wide. The frame of

the unit was visible but was not as conspicuous as a

1-1/4 inch diameter mast nearby. Since the mast was

somewhat darker than a transmission line probably would

be, a 1-1/4 inch aluminum bar was observed and found to

be possibly a little less conspicuous than the mast but

just as visible as the unit.

When the lamp was lit a faint glow appeared in the

unit, but, in the opinion of the observers, this did not

add to the conspicuity of the unit under the conditions

of observation. A black-cloth background increased the

visibility of the lamp but not to a marked degree.

From these observations it was concluded that the

unit would be of doubtful value when viewed against a

sky background in the daytime. Allowing for a size

factor of 3, the visual range of the unit at night should

be about 1/4 mile when the visibility is 1/4 mile. Under

this condition the unit would be about as effective as a

25 candlepower lamp. With an atmosphere sufficiently clear,

the visual range will be such that the unit may be considered a point source at its extreme range. Under such

conditions, the visual range will be limited by the candlepower alone, as in the case of the usual incandescent unit.

With the most favorable conditions, the maximum candlepower

of the unit, 95 candles, will give a visual range at night

of more than 10 miles.

N

BS

Test

2IA-2/55

Figure

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NBS Test 2IA-2/55 Figure I

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NBS Test 2! A- 2/55 Figure HL D


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Figure 8

STATUS OF PINK BOLLWORM

Hmm

NO INSPECTION

INSPECTED - NEGATIVE

TRACE OR VERY LIGHT - LESS THAN 1/ 10 LARVAE PER BUSHEL

LIGHT - 1/10 TO I LARVAE PER BUSHEL

THREATENING - 1+ TO 10 LARVAE PER BUSHEL

SEVERE - 10+ TO 100 LARVAE PER BUSHEL

HEAVY- (ECONOMIC LOSS) -OVER 100 LARVAE PER BUSHEL

BASED ON GIN TRASH SAMPLINGS OR EQUIVALENT

Gulfport. Mis 4- 4

- -S3 Lf\B

INFESTATIONS AS OF JAN. 1958

NBS Test 2IA- 2/55 Figure 10

>

65

60

55

50

45

40

35

30

25

20

15

10

5

0

21A-2/55

Transmission Line Current: Amperes

Figure 12

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

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

Standards, Washington 25, D. C.
(