Fluke 43B Case Studies

Application Note

Problem description

In most facilities, lighting is a
major element of operating
cost. Part of that cost is due
to energy, and part is due to
maintenance. The maintenance
costs can be significant. Light
fixtures require periodic mainte­nance — for example, lamps
burn out, ballasts fail and
lenses need cleaning. The
amount of maintenance
required varies with the age
and design of the lighting
fixtures. The logistics of that
maintenance (e.g., needing a
personnel lift for high ceiling
areas) can magnify “typical”
cost estimates by an order of
magnitude. It is sometimes cost­effective to replace an entire
system with a more efficient
one. In the case described here,
the owner decided to replace
the entire system.

While reducing the mainte­nance costs was the driving
force in obtaining a replace­ment system, reducing energy
costs was the driving force in
selecting a replacement system.
Determining the actual reduc­tion in energy consumption
required significant research.
The research was difficult,
because there was no common
platform for comparing the
widely varying performance
claims from competing suppli­ers. Sometimes, critical specs
were missing altogether.

Lighting ballast

evaluation

From the Fluke Digital Library @ www.fluke.com/library

The plant engineer decided
to compare various units side­by-side, in the field. He began
by asking each supplier to
submit a sample for evaluation.
Next, he worked on determining
what to measure and how to
make the measurements. The
final measurement criteria
included measurements of
power consumption, power
factor, displacement power
factor and harmonic spectrum.
Power consumption and
displacement power factor
would translate directly to
operating cost. Harmonic distor­tion was of interest, because
the plant engineer knew that
high levels of harmonic current
could cause problems for trans­formers, circuit breakers and
other parts of the electrical
distribution system.

To make these measurements
easy, the plant engineer chose
the Fluke 43B. The electrical
team made measurements using
a setup similar to Fig. 1. This
is an experiment that you can
easily duplicate on your work­bench.

10 Turn Coil

Fig. 1 Example test set up for compact fluorescent lamps

Operator: Plant engineer or plant
energy manager

Measuring tools: Fluke 43B Power
Quality Analyzer

Features used: Voltage, kW, PF,
DPF, THD

Power
Quality

Case
Study

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Printed in U.S.A. 8/2003 2103512 A-ENG-N Rev A

conditions vary between manu­facturers and the conditions
differ from actual applications.
Therefore, those claims, while
made in good faith, can be a
poor basis for a final product
decision. When trying to make
economic decisions on lighting
or other electrical applications,
measuring actual performance
under actual conditions — with
the right test equipment — is a
sure way to arrive at the best
decision.

Ballast/lamp Power
supplier consumption P.F. D.P.F. Current THD Unit cost $

Brand A 14 W 0.63 0.96 74.3 % $6.50
Brand B 16 W 0.59 0.98 77.1 % $8.00
Brand C
Brand D

Fig. 2 Compact fluorescent lamp power
consumption and current waveform

Fig. 3 Compact fluorescent lamp current
harmonic spectrum

They recorded data in the
matrix table shown here. From
the table, you can see they
were able to make comparisons
of all the key electrical factors
on a level playing field. This
allowed them to select the most
cost-effective approach.

It’s worth noting that each
manufacturer bases its perform­ance claims on a specified set
of operating conditions — these
conditions may be ideal or they
may be “typical.” But, the

Notes to table:

1. The comparison test for compact fluorescents can easily be demonstrated using a desk

lamp and a split extension cord with one conductor wrapped in a 10-turn coil. The
10-turn coil increases the range of current measurement. Power consumption for one
unit would be the recorded value divided by 10.

2. To make a fair comparison, the line voltage should be the same for each unit tested.

3. The performance value of current TH D w ill depend on the amount of harmonic distortion

on the supply voltage and impedance of the voltage source. It may not be possible to
duplicate the ballast suppliers’ exact specification number — but, if all tests are made from
the same supply source, the performance comparison will be valid.

4. Measurement values for the lamp tested in Fig. 2 and Fig. 3 are recorded as “Brand A .”

The remaining tests for brands C and D are left as an exercise for the reader.

Line voltage: 119.2 V ac
Line voltage THD: 2.7 %

2 Fluke Corporation Power Quality Case Study: Lighting ballast evaluation