Re: How to get the output from the light dimmer?

On Sun, 23 Oct 2005 22:05:06 +0100, Bill Williams <jwjw@xxxxxxxxxxxxx> wrote:

In article <1130053431.135899.62710@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
 "ooi_yw" <yuwei_1712@xxxxxxxxxxx> wrote:

Hi guys, as far as i know, light dimmer produces harmonic distortions
to the main supply. In order to check the distorted waveform which
contains many levels of harmonics, where should I check the output? I
mean is if i want to use an oscilloscope to capture the image of the
distorted waveform, where should I put the probe of the oscilloscope.

Hope you guys can help me. Thanks. 


I don't want to sound facetious, but seriously, why do you want to know?

The easy answer is that for most purposes, if the dimmer is controlling
a resistive load the waveform doesn't matter to the load. If the dimmer
is controlling a motor or other inductive load, or another electronic
load, then either the load or the dimmer is likely to be damaged; tell
us what sort of load and what sort of dimmer we may be able to qualify
this answer.

On the other hand, the load the dimmer puts on the mains supply may
possibly distort the supply waveform. But for most cases the supply
impedance is low enough that it will just absorb the harmonics without
much harm. The only case where this may matter is if the supply comes
from a small generator or some sort of electronic inverter, in which
case let us have more details and maybe we can help. For the usual
public supply there is no real problem but the supply company may want
to know if we are talking about a load of tens of kilowatts or more.

Bill.

Which would be the case for most theatre installations. So no dimmer doubling here.
.

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