Case Studies

Application Note
Problem Description:
Ever fixed something and still
not solved the problem? Some-
times multiple deficiencies can
all cause the same symptoms.
In this case, an industrial
facility was having communica-
tion problems with a network
hub. During the initial survey
data gathering phase, they
documented equipment failures
and port problems all the way
back to the hub equipment
installation.
After the service company
exhausted all hardware and
software options, they called in
a consultant to find out whether
it was a power quality problem.
Using his handheld Fluke 434
three-phase Power Quality
Analyzer, the consultant found
more than expected.
Measurements:
After connecting his Fluke 434
to the branch circuit supplying
the hub equipment, he checked
the View Config screen (Fig. 1)
diagram to verify proper connec-
tions. From there, he pushed the
Scope button and saw an abnor-
mally high neutral waveform.
(Fig. 2) He checked the numeric
values at the top of the screen
and saw that neutral voltage
was in fact incredibly high, at
23 volts, indicating a possible
neutral-ground issue. He saved
that screen for customer docu-
mentation.
Just to be sure, he switched
to the V-A-Hz screen (Fig. 3)
and checked the voltage level
again. He got the same results.
Following standard power qual-
ity practices, he began looking
for a grounding problem at the
branch circuit, since that was
the next step in the wiring path.
Network
hub failure
From the Fluke Digital Library @ www.fluke.com/library
Measuring tools: Fluke 434 Power
Quality Analyzer
Features:
Scope, V-A-HZ, Monitor,
Trend, Events, ground
Power
Quality
Case
Study
Fig. 1 View configuration screen
Fig. 2 High neutral waveform
Fig. 3 Voltage level check