Application Note

ManualsBrandsFluke ManualsPower Quality AnalyzersFluke 437 Series

Application Note

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.

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.

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

Troubleshooting

commercial

lighting loads

Measurements on commercial lighting loads

Measurement

ook for

1. Power consumption (kW) Balance among three phases.

2. P

er F

actor (DPF and PF)

Mag

netic ballast w

ill ha

ve low DPF. Electronic ballast may have low total PF, although new

generations of ballast often ha

ve harmonic mitigation built-in

3. T

otal Harmonic Distortion (%THD)

Current %T

HD <20 % is desirable.

4. Voltage Stability Unstable voltage can cause lights to flicker.

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.

3. Total Harmonic Distortion

Current THD should be consid-

ered 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.

Summary of content (2 pages)

PAGE 1
Troubleshooting commercial lighting loads Application Note 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.
PAGE 2
Ø1 480 V Phase-to-Phase Ø2 Ø3 277 V Phase-to-Neutral A B C N The Fluke 43B Power Quality Analyzer trends voltage (top) and current (bottom) simultaneously. Current swells/ inrush caused voltage sags, indicating that a load downstream from the measurement point is the cause of the disturbance. Lighting Panel Single phase analyzers measure each ballast separately, requiring manual calculations. Three phase analyzers measure all three phases simultaneously and perform the calculations automatically.