APR wrote:pulsetech wrote:Amps x Volts = Watts
so say 10 amps x 240 volts = 2400 watts
or 10 amps x 100 volts = 1000 watts
this is output amps from your controller not Input
if that helps
I am trying to get my head around the fact that the current flow will be zero at the AC voltage zero crossing point, and will peak at the peak of voltage. This means the current at any point of adjustment of the power controller will be dependent upon what part of the sinusoidal waveform is chopped out.
Would a Watt Meter be accurate when downstream of these SCR power controllers?
APR ,AC voltage ( and current) are RMS which means root mean square....you are absolutely right ,the instantaneous value of a mains cycle is varying.So RMS is the equivalent DC voltage that would cause the same heating effect on an element .
RMS is obtained by taking many samples throughout the cycle and averaging them .The more samples ,the greater the accuracy .You are also correct that with a pure resistive load, the current at any sample point will be proportional to the voltage
In a simple circuit where the load is a resistance and it is not fucked up by a phase controller , the RMS voltage is 0.707 x Peak voltage .
So the peak voltage is around 340V for a 240vAC
Simple meters rectify the AC voltage and scale it .............Great if its a sine wave ....but when its chopped up by a phase controller , you need a true reading RMS meter which samples and averages to get the "TRUE RMS"
Here's a Friday night crayola special. First pic is how RMS is determined on a pure sinewave and second pic is in a sinewave chopped up by a phase controller
RMS ....all negitive cycles are flipped as positive ...energy is energy :handgestures-thumbupleft:
So all the "bits" above the RMS line fill in all the gaps in the cycle below the RMS line :think:
RMS.jpg