Case Studies

2 Fluke Corporation Electric utility plays it safe with Fluke T
+
Electrical Tester
function, liked the tool’s ability
to test all three power phases
and determine the phase rota-
tion between any two phases.
The team also had sug-
gestions for the Fluke design
engineers, such as larger
buttons for gloved hands
and a battery life indicator.
They noted that the unit was
designed to measure voltage
even if the batteries for the unit
were depleted or missing. The
T+PRO test leads took some
getting used to, but the unit
does come with velcro wraps
and on-unit probe storage to
help keep them under control.
When they tested the Fluke
T+PRO on the job, the field ser-
vice team liked its ease of use
and multiple signaling methods
(LCD, LED, sound and vibration)
and its built-in flashlight, and
felt the unit was built tough
enough for daily industrial use.
They also appreciated its added
features for resistance, continu-
ity and GFCI testing. One rep
commented that the Fluke tool
detected a small load—a tran-
sistor radio left on—that the
solenoid tester did not pick up.
Another group of employees,
the meter electricians who
actually test electric meter
The Fluke T+PRO passed
the field tests, and the utility
is adding the tool as a stan-
dard to replace all of the old
solenoid-based testers. “These
devices worked perfectly,” the
supervisor said. “They do what
they are intended to do and
they have very nice features.
We’re going to bring them in
as a regular stock item in our
warehouse,” he said. And, in
addition to the 25 field service
representatives, and the meter
electricians, they anticipate that
the overhead and underground
crews too will adopt the Fluke
T+PRO.
Solenoid-based Testers: What’s the Buzz?
Their compact size and rugged-
ness have made solenoid-based
electrical testers a traditional
favorite for electrical industry
professionals, but advancing
safety standards are leaving
these devices behind. These
classic testers are no longer
safe to use by NFPA electrical
measurement standards and not
CAT rated by the International
Electrotechnical Commission
(IEC). Many companies have
outright barred them from use.
A solenoid depends on the
movement of a ferrite slug in
response to the energization
and de-energization of an elec-
tromagnetic coil. The indica-
tion function of these testers
depends on a spring, which
drives a mechanical pointer.
The spring restrains the slug,
which slides to one end of its
chamber or the other, depend-
ing on whether the coil has
enough energy to cause the
slug to overcome the opposing
force of the spring. Unfortu-
nately, solenoid-based testers
have several shortcomings:
•
The amount of energy
required restricts their
sensitivity. In the US, a
useful solenoid-based tester
will measure voltages up
to 480 V or more. But the
poor dynamic range of the
magnetics limits the ability of
such a device to detect volt-
ages below about 100 V.
•
Solenoid-based testers have
relatively low input imped-
ance—10 kilohms at the
upper end, but often as low
as 1 kilohm. So solenoid-
based testers can easily
make their presence felt in a
circuit as loads and interfere
with the operation of that
circuit. The relatively high
current draw also creates
enough heat that the testers
can quickly overheat, even
to the point of damaging the
tester.
•
These testers are gener-
ally unable to comply to
IEC 61010 due to excessive
current draw, poor dielectric
withstand performance and
impulse destruction due to
transients originating from
the mains. This is one reason
many companies forbid the
use of voltage testers on
anything but 24 V control
circuits, and some forbid
them altogether.
•
The high current flowing
through solenoid-based
testers has another down-
side. You can easily carry a
lethal current through the
tester. Wearing insulated
gloves can reduce the shock
hazard, but you’ll also be
risking an arc hazard with
each use.
Fluke Corporation
PO Box 9090, Everett, WA 98206 U.S.A.
Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The Netherlands
For more information call:
In the U.S.A. [phone] or
Fax [phone]
In Europe/M-East/Africa [phone] or
Fax [phone]
In Canada (800)-36-FLUKE or
Fax [phone]
From other countries [phone] or
Fax [phone]
Web access: http://www.fluke.com
©2007-2009 Fluke Corporation.
Specifications subject to change without notice.
Printed in U.S.A. 3/2009 3057495 A-EN-N Rev C
Modification of this document is not permitted
without written permission from Fluke Corporation.
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up and running.
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