Re: Anyone moved to LED Lighting?

[don@xxxxxxxxxxxxxx (Don Klipstein)]

In article <b19%m.2094$Gf3.636@xxxxxxxxxxxx>, Josepi wrote:
>I haven't seen a big box store or a grocery store, that uses fluorescents,
>built in the last twenty years.
>They all used HID lighting of some type. Of course they are even worse for
>third harmonic content than CFLs.
>
>People do not like the flicker of fluorescents, as it irritates the nervous
>system but I am not sure the HID lighting is any better for persistence of
>light. Count the number of fights in the grocery store and compare...LOL

  HPS is much worse in that area.  And fluorescent with electronic
ballasts have close to no flicker at all at frequencies related to the
power line.

>Third harmonics take a special winding design to reduce the passing of third
>harmonics to the generating source. Usually use of a zig-zag secondary
>winding causes cancellation of any balanced multi-phase third harmonics.
>This, in effect causes two phases to subtract their in phase components. In
>a three pahse system third harmonics are typically all in phase between all
>phases.
>
>Neutral reactors are typically used in large tranformers and consist of a
>large air core reactor. These  reduce fault current to manageable levels but
>convert many third harmonic currents into voltage problems which radiate the
>problem to the rest of the system loads.
>
>We ran into some interesting concepts with this on 100MVA transformer
>voltage sensing. If the third harmonic crosses zero exactly the same time as
>the fundamental the peak of the waveform is higher. If the third harmonic is
>phase leading it lowers the peak of the fundamental.

  How is the fundamental changed by presence of a harmonic?

>This can play havoc
>with a lot of sensing equipment without massive filters. We leave this
>problem with the grid delivery system people to replace every $5M-$20M
>transformer in their system.  Cheaper lighting? You bet.

  I have seen the current waveforms of CFLs, even in my own experience.
Those spikes are drawing current at the time the line voltage peaks, not
leading the peak of line voltage by a lot.

  Also, even a low power factor CFL draws significantly less current than
the incandescent it replaces.

 - Don Klipstein (don@xxxxxxxxx)