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Harmonic - LED Lights

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anbm

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Will LED down lights create more harmonic in system more than compact fluorescent? How does this harmonic created by LED affect the electrical system in overall?Do lighting manufacturers or U.L. allow max. TDH % each LED light must have or listed before it can be sold to the user?
 
Flicker Index

Flicker Index

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anbm said:
Will LED down lights create more harmonic in system more than compact fluorescent? How does this harmonic created by LED affect the electrical system in overall?Do lighting manufacturers or U.L. allow max. TDH % each LED light must have or listed before it can be sold to the user?
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The vast majority of CFLs have a PF of about 0.5 with a THD often exceeding 70%. The flicker percentage of LEDs are almost always worse than CFLs but the front-end of LEDs are such that PF usually exceeds 0.8 and correspondingly lower THD. LEDs you can buy today have much, much, lower inrush current than CFLs or old LED lamps.

Part of that is Energy Star specs, and part of it is because the front-end for dimmable LEDs tend to have lesser THD and there's strong expectations of dimmability in the north american market.
 
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anbm

Senior Member
Location
TX
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Designer
Flicker Index said:
The vast majority of CFLs have a PF of about 0.5 with a THD often exceeding 70%. The flicker percentage of LEDs are almost always worse than CFLs but the front-end of LEDs are such that PF usually exceeds 0.8 and correspondingly lower THD. LEDs you can buy today have much, much, lower inrush current than CFLs or old LED lamps.

Part of that is Energy Star specs, and part of it is because the front-end for dimmable LEDs tend to have lesser THD and there's strong expectations of dimmability in the north american market.
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Do you know any manufacturer white paper or technical document about this comparision?
 
Flicker Index

Flicker Index

Senior Member
Location
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Are we talking about residential or commercial?

Whenever you do a pass-through dimming (filament, LED, CFL, heating elements or whatever), you will have harmonics, because the current waveform (chopped up) will not be the same as the line waveform. However, to use this type of dimming, the front-end (bridge + fattie o electro cap) used in non-dimmable CFLs are simply not compatible so this is why LED lamps almost always have less THD in non-dimmed state.

Also, read up on the latest Energy Star specs for lamps. The Energy Star reqs are
≥ 0.6 for Omnidirectional LED bulbs with input power ≤ 10 watts. ≥ 0.7 for all other LED bulbs

It's not the law that they have to be Energy Star rated, but subsidies and incentives are generally not offered on lamps that are not EnergyStar, so manufacturers are deeply interested in offering those that meet the reqs. Much like doctor's office being concerned with what HMOs cover.
 
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