Troubleshooting commercial lighting loads

Commercial lighting loads are a major load for large facilities. Troubleshooting them can often be challenging but it's important to
evaluate these circuits for both 1) energy conservation and 2) power quality purposes. They are wired single phase, with the loads connected from phase to neutral. Typically, the phase-to-phase voltage is 480V, with the phase-to-neutral voltage at 277V. Measurements need to be taken at the lighting panel, one phase at a time, since power consumption and Power Factor could vary on each phase.
Some points to consider:
1. Power consumption: Excessive phase unbalance can cause voltage unbalance, which in turn can affect three-phase
motor loads.
2. Power Factor: Ballast with low PF might have lower cost-of-purchase but higher cost-of-operation.
3. Total Harmonic Distortion: Current THD should be considered when selecting ballast, especially if there is a possibility of transformer overloading
4. Voltage stability: I've found the sags and swells mode of the Fluke (http://www.fluke.com /) 43B (http://us.fluke.com/fluke/usen/Power - Quality-Tools/Single-Phase/Fluke-43B.htm?PIDV080) to be especially useful for recording repetitive voltage sags which can show up as flickering lights. Both current and voltage are monitored simultaneously. This helps me to tell if sags are downstream of the measuring point (load-related) or upstream (source-related). For example, if voltage sags while current swells, a downstream current inrush likely caused the sag. If both voltage and current sag, some event upstream caused the sags.
It could be an upstream load like a motor on a parallel branch circuit which drew down the feeder voltage. Or it could be source voltage related, for example, a lightning strike or breaker trip/reclosure on the utility.
I hope this helps!
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Steve Glad wrote:

Looks like oatmealrunner, the Fluke marketing droid, may have a new name.
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Is this some kind of ad for Fluke? I prefer a Simpson analog meter for inductive circuits because those digital meters have behavior problems. Those little square waves go haywire on inductive loads.
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I sure wouldn't have expected Fluke to stoop to such lows as usenet spam in promoting their products. I'm generally a big fan of their stuff.
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We electricians like to load the circuit when we test it. That is why a wiggy is still used. High impedance flukes are to light on the load and give erratic readings. They have screwed me up more than once.
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Outside you will have things like street lights to help keep your parking l ot illuminated. This is important for the safety of your customers and your employees. You will also have security lights which are used near doors an d various access points around the building. Most businesses also have ligh ted signs. There are several different types of commercial lighting that yo u will find indoors as well. You might use floodlights to illuminate a load ing dock. Low bay light fixtures are used in buildings where the ceiling he ight is between 15 and 20 feet. This type of lighting provides good illumin ation without too much glare. High bay light fixtures are normally used in areas where the ceiling height is in excess of 15 feet. Read more about com mercial lighting here http://hibritelighting.com/commercial-lighting/
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