Quite correct, but from the context it was clear that both TNP and Ian were both talking about an asymmetrical square wave with a DC component equal to half the peak value. Here the RMS value is 1/sqrt(2) times the peak value.
Industry takes power factor correction very seriously. The vast increase in the use of switchmode power supplies, it's much more complicated these days. Have a read:
Perhaps not. I recall a newspaper reveiwer saying of Horizon many years ago "It's OK if you have a degree in science, but for the rest of us..."
I don't watch it any more.
Andy
That's right, but surely for a pure resistance, there is no phase lag or lead so VA and Watts are synonymous and VA does give the actual power delivered.
SteveW
Power dissipated in the wire will be directly proportional to the RMS current. I^2 R and all that...
I do... had it for ages.
Well if the current is continuously falling, then it can never be higher than at max brightness.
Not relevant - current and resistance is what counts.
Peak current won't give you the time averaged heating effect.
You're right, but the only pure resistive loads in this building are the convector heaters, the cooker, the toaster and the kettle. All the lights are CFL or halogen with a transformer, and as for the electronics...
The problem with a non-unity power factor (AKA non-resistive load) is that the current drawn is higher for the same power use than for a resisitive load.
If you take a standard 40W flourescent fixture, as found in most offices from the 50s until about 2000, without the power correction capacitor, they drew as much current as a standard 75Watt light bulb, roughly. The grid, your building power cabling and the generators all needed to be heavier than if the PFCs were fitted to minimise transmission losses. This is why all retail flourescent fittings that used the old choke ballasts came with a PFC built in.
That's not what you meant to write. Insert "the square of" :~)
Quite.
Horizon is now dumbed down so is only really for children.
Eh?
I think he means if its chopped asymmetrically it introduces a DC bias.
Yes on reflection that definition of "proportional to" would require the substitution of an interesting "constant" resistance! ;-)
It doesn't have to be DC. As an example, taking the part of each half wave moving away from zero volts would move the current wave relative to the voltage.
Andy
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