Application Note

3 Fluke Corporation Lighting the way at Minneapolis-St. Paul International Airport
As Litke explains it, each run-
way light is a 6.6 V unit sitting
on its own transformer. The
lighting string is fed through a
constant wattage regulator that
makes 6 amps available at each
light
. When all wiring is property
maintained, 500 volts will power
the system need. However, as
wires degrade and leakage to
ground increases, the system
self-corrects, increasing supply
voltage as high as 3500 V just to
keep 6 A at each light. Prevent-
ing that electrical cost puts
wiring insulation integrity at
premium importanc
e.
Fluke Corporation
PO Box 9090, Everett, WA USA 98206
Fluke Europe B.V.
P
O Box 1
1
86, 56
02 B
D
Eindhoven, The Netherlands
For more information call:
In the U
.S
.A
. (8
00) 443-5853 or
Fax [phone]
In Europe/M-East/Africa (31 40) 2 675 200 or
F
ax (3
1 40) 2 675 222
In Canada (800) 36-FLUKE or
Fax [phone]
From other countries [phone] or
Fax [phone]
Web access: http://www.fluke.com
©2004 Fluke Corporation
. All rights reser
ved
.
Printed in U.S.A. 7/2004 2155809 A-US-N Rev B
Fluke. Keeping your world
up and running
.
Litke also believes the 1520
has lowered labor costs. “The
1520 is not only versatile and
adaptable to our maintenance
needs, but is so reasonably
priced that we were able to buy
1
4 units. On a facility the size of
MSP with technicians scattered
anywhere across its acreage, it
makes sense to have more than
one or two. If the department
can have one on each truck —
and quickly locating an electrical
problem often requires multiple
vehicles — technicians never
have to make unnecessary trips
across the airport to check one
out of the maintenance building.
Repairs get done quicker and
more efficiently.”
Fewer trips, says Litke, add up
to lower c
osts and increased
safety. “‘Less windshield time’ is
much safer at a busy airport.
Fewer vehicle movements lessen
the possibility of interfering with
flight operations and runway
accidents.” And that’s exactly
what the airport wants to hear.
Meanwhile, on the other side of the world
A far cry from the upper Midwest of the United States, New Zealand is comprised
of a pair of islands, situated 1,200 miles southeast of southern Australia. New
Zealand is a rugged land-three-fourths of its approximately 104,000 square miles
is hills or mountains.
The Fluke 1520 MegOhmMeter has also become the electrical tool of choice for
maintaining runway lighting at Airways New Zealand’s multiple airport facilities.
According to John Meyer, Wellington facilities manager for Airways Corporation of
New Zealand Ltd., “We currently have 18 Fluke 1520 MegOhmMeters in service.
Although adaptable to a wide variety of electrical troubleshooting and mainte-
nance duties, they are mainly used to maintain Airways’ Airfield Lighting systems
(AFL) throughout New Zealand at 15 airports.”
Just like airports worldwide, Airways New Zealand’s AFL is a standard system
that uses a series circuit to feed the runway lighting. The circuit runs at 6.6 A
when at the lights are at full brilliance. Each circuit has about 1- 2 KV applied to it
by a constant current regulator power supply. Each light has an individual trans-
former in an underground ‘pot’ that runs the light. An individual circuit can be
many kilometers in length and can have 100 or more lights.
Because insulation degradation can be a problem, even in the equable and
moist New Zealand climate, Mr. Meyer’s crew of electricians and technicians use
the Fluke 1520 to monitor insulation integrity. “Our methodology for checking cir-
cuits is standard for all facilities we operate and is the same as used worldwide by
other airport facilities. The 1520 is used to check for leakage to ground of a series
circuit using its 1,000 V range. This gives a technician a good indication of circuit
insulation condition. If the resistance falls below 1.5 M
Ω, repairs are initiated to
bring the insulation resistance back up to above 4 m
Ω,” Meyer says.
The capabilities and ruggedness of the Fluke 1520 have given Airways New
Zealand an efficient method for making and checking repairs. John Meyer com-
ments, “During repairs, it is necessary to measure the insulation resistance of sec-
tions of the circuit in the field and the Fluke 1520 has stood up to this work well.
The 1,000 M
Ω dynamic range of the 1520 is essential for accurate leakage testing
of current transformers. During these tests, it is necessary to detect leaks in the
order of 8 M
Ω because transformer leakage is in parallel and there may be 100 or
more lights/transformers on a circuit. At 8 M
Ω per transformer and 100 transform-
ers, total leakage would reach 800 M
Ω. We have used 1520s since 2001 and have
not had any meters go faulty or go out of tolerance.”
John Meyer is also delighted with the 1520’s ease of use. “Our technicians and
electricians like the 1520s. They are simple and quick to use. Their readouts are
clear and easy to read. We are very pleased with the product.”