Fluke 434 II, 435 I, 435 II, 437, 437 II Service Guide
...
Troubleshooting
commercial
lighting loads
Lighting is a major load for many large facilities.
Evaluating these circuits is important for both
energy conservation and power quality. Keep in
mind that commercial lighting loads are wired single
phase, with the loads connected from phase to
neutral. Typically, the phase-to-phase voltage is
480 V, with the phase-to-neutral voltage at 277 V.
Measurements must be taken at the lighting panel,
on all phases, since power consumption and Power
Factor could vary on each phase.
Application Note
1. Power consumption
Excessive phase unbalance can
cause voltage unbalance, which
in turn can affect three-phase
motor loads. For example, in this
three-phase reading, phase A is
considerably higher than B and
C, when all three phases should
be equal.
2. Power Factor
Ballast with low PF might have
lower cost-of-purchase but
higher cost-of-operation. This
phasor diagram illustrates the
unbalance along with the power
factor.
Measurements on commercial lighting loads
ook for
Measurement
1. Power consumption (kW) Balance among three phases.
actor (DPF and PF)
er F
ow
2. P
otal Harmonic Distortion (%THD)
3. T
4. Voltage Stability Unstable voltage can cause lights to flicker.
L
ve low DPF. Electronic ballast may have low total PF, although new
netic ballast w
Mag
generations of ballast often ha
Current %T
ill ha
HD <20 % is desirable.
ve harmonic mitigation built-in
3. Total Harmonic Distortion
Current THD should be considered when selecting ballast,
especially if there is a possibility
of transformer overloading. The
bar graph pinpoints the 5th and
7th harmonics as the larger
contributors.
.
From the Fluke Digital Library @ www.fluke.com/library
The Fluke 43B P
Ø1
Ø2
Ø3
N
Lighting Panel
ABC
277 V Phase-to-Neutral
480 V Phase-to-Phase
voltage (top) and current (b
ously. Current swells/ inrush caused voltage
sags, indicating that a load downstream from
the measurement point is the cause of the
disturbanc
ower Quality Analyzer trends
ottom) simultane-
e.
Single phase analyzers measure each ballast separately, requiring manual calculations.
Three phase analyzers measure all three phases simultaneously and perform the calculations automatically.
4. Voltage stability
The sags and swells mode of
power quality analyzers is
especially useful for recording
repetitive voltage sags which can
show up as flickering lights. Both
current and voltage are monitored simultaneously. This helps
us tell if sags are downstream of
the measuring point (loadrelated) or upstream (sourcerelated). For example, if voltage
downstream current inrush likely
caused the sag. If both voltage
and current sag, some event
upstream caused the sags
e an upstream load
ould b
It c
like a motor on a parallel branch
ircuit which drew dow
c
feeder voltage. Or it c
source voltage-related, for
example, a lightning strike or
breaker trip/reclosure on the
utility distribution system.
sags while current swells, a
2 Fluke Corporation Troubleshooting commercial lighting loads
.
n the
ould be
The Fluke 430 Series Power Quality Analyzers
trend all three phases and compares interaction between the loads.
eping your world
Fluke. K
e
up and running.
Fluke Corporation
O Box 9
P
Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The N
For more information call:
In the U.S.A. (800) 443-5853 or
ax (425) 446-5
F
In Europe/
Fax (31 40) 2 675 222
In Canada (800) 36-FLUKE or
ax (9
F
From other countries +1 (425) 446-5500 or
Fax +1 (425) 446-5116
Web access: http://www.fluke.com
©2004 Fluke Corporation
Printed in U.S.A. 10/2004 2403043 A-US-N Rev A
0
05) 89
9
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0, Everett, W
etherlands
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1
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5 200 or
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