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Nicholas[_2_]

On Wed, 31 Oct 2012 21:30:27 -0400, wrote:

On Thu, 01 Nov 2012 09:54:13 +1100, terryc
wrote:

On 01/11/12 02:01, Jim Elbrecht wrote:

Am I all wrong here? Do traffic lights need more juice than an
inverter could supply? [granted there are 8 lights at the
intersection, but they are LED-- plus the switching equipment]

Yes. There is a fair bit of power involved in lights and cabinents.

Also, it is easier to train people to start, refuel and stop a
generator, than it is to deal with deep discharge batteries and the
inverter.

Also, when you start doing the figures, there can be some heavy currents
running through the cables from the "battery" to the inverter.

Generators are heavier and less portable than batteries and inverter.

then there is the question of the wave form in the inverter Vs the
desired sine wave form of the generator.

Which for the traffic lights could likely be a square wave with
little or no effect.

These days inverters produce "modified sine waves" which is a
stair-step kind of output. Not a square wave, not a sine wave, but a
blend of both.

I know from experience that electric motors don't like that kind of
input. They run at very low rpm with an MSW. I don't know what the
root mean square (rms voltage) is but I suspect it is a lot less than
0.707 of the peak to peak voltage that you would get with a pure sine
wave.

Lg