Nigel, so to be clear? Your Euro 240v 3 pin plug home electrical wall socket service is actually 2 hots and 1 neutral, and NOT 1 hot, 1 neutral, and 1 separate ground, as it is here in the States? We call your type of service here as, 220v single phase power.How would 0 to V+ be the same as V- to 0 to V+?, obviously it's only half. And assuming 240V mains, the output of a half wave rectifier is 120V RMS.
And it's not changing the mains (unless you have a high current draw on it), it's simply changing what appears on the output of the diode.
Historically TV's used half wave rectifiers, but after a while the electricity companies insisted that they used full wave ones - back in the old two pin plug days it didn't matter, it was random choice if a TV used the positive half cycle, or the negative one, so it balanced out. But once 13A 3 pin plugs were in universal use the VAST majority of TV's were running off the positive half cycles, leaving the negative half cycles unused - and this created a negative bias on the electrical system which the electrical companies didn't like
It still applies. For the raw AC, W for one half cycle is exactly the same as W for the next half cycle, so if you remove alternate half cycles (which is what the half-wave rectification does) you end up with W/2 average.
Nigel, so to be clear? Your Euro 240v 3 pin plug home electrical wall socket service is actually 2 hots and 1 neutral, and NOT 1 hot, 1 neutral, and 1 separate ground, as it is here in the States? We call your type of service here as, 220v single phase power.
No, it doesn't. The result is 0.707 times the original.adding a half wave rectifier reduces the RMS VOLTAGE by half
OK, confused again. Why isn't it simply 50%? How does the on cycle vary because there is an off cycle?No, it doesn't. The result is 0.707 times the original.
Don't be. The on half-cycle is unaffected. The off half-cycle reduces the long-term RMS voltage and power. The 0.707 figure (half the square root of 2) and the posted sim relate to long-term RMS voltage, not power. Long-term average power gets halved.OK, confused again.
Yay, happy again. And maybe had a little too much wine. Time for bed.Don't be. The on half-cycle is unaffected. The off half-cycle reduces the long-term RMS voltage and power. The 0.707 figure (half the square root of 2) and the posted sim relate to long-term RMS voltage, not power. Long-term average power gets halved.
Considering a resistor as the load here, wattage is measured as the amount of heat, (work and/or horse power), produced or emitted from the load. With the half wave rectifier inline there is NO heating going on during the periods of no pulses; so there IS 1/2 less wattage than with either the full wave rectified signal that has the same amount of pulses as the full AC sine wave. The full AC sine wave, also has double the voltage in the circuit, because the voltage is measured top to bottom of any waveform, that is applied across the load. In this case (for the full 240v AC sine wave), 120v for the top + swinging side of the waveform, and 120v for the - swinging side of the waveform. (+)120v + (-)120v= 240v total. Where as, in the half wave or full wave rectified waveforms only swing + 120v from the "0" reference line. (Disregarding whether we are measuring the voltage at the peak, average, or RMS voltage level.)It still applies. For the raw AC, W for one half cycle is exactly the same as W for the next half cycle, so if you remove alternate half cycles (which is what the half-wave rectification does) you end up with W/2 average.
So that means 480v approx. or slightly less (416v) across two different phase hot or "live" line wires?You're wrong in every respect, the UK doesn't use the inferior Euro plugs, and our mains is 240V single phase to domestic premises (split off from 3 phase, with alternate houses on alternate phases). This balancing allows the use of a thinner neutral wire in the distribution system, as it reduces neutral current greatly (to zero if perfectly balanced).
The UK 13A sockets used are live, neutral and ground.
So that means 480v approx. or slightly less (416v) across two different phase hot or "live" line wires?
No, it doesn't. The result is 0.707 times the original.
Indeed it is.0.707 is simply the multiplication factor for peak to RMS
Roger that! I use to work for my dad in his machine shop business as the shop forman, before I went into electronics, and the building had both single phase and 3 phase 220v service. When we added 3 single phase air conditioning units to the building a few years later, it was more convenient to wire them into the 3 phase copper buss bars we had installed in the building to power all of the heavier machinery; instead of running individual single phase lines. We had to wire them in a fashion so as not to upset the balance of the 3 phase, or some times certain motors would not start, or blow a fuse or breaker. So I am very familiar with the BUZZ! There were also other single phase machinery wired into the buss bars too.The usual figure is given as 415V, and is what is supplied to industrial users. Where I used to work we had a small goods hoist/lift and that rather bizarrely used three phase, even though it wasn't a very large motor. Interesting though because different parts of the building used different phases, and if you lost power in part of the building you could tell if was an external or internal problem by trying the lift - if one phase was lost it just buzzed, so you knew the problem was external. The service department where I used to work had three phase coming in, but only a single phase was used - presumably they had to dig outside to run the cable, so it made sense to run a 3 phase one 'just in case'.
That depends upon whether you are talking about having either a full wave (2 diode) rectifier circuit that is connected to a center tapped transformer input supply, or using a full wave (4 diode) bridge rectifier circuit with the same AC voltage potential at it's input. The full wave bridge rectifier circuit would have twice the DC voltage on it's output compared to the center tapped full wave rectifier circuit version.So Nigel maintains that operating a light bulb from 220V AC RMS would be twice as bright as operating the same bulb from full-wave rectified DC with the same RMS voltage because the peak-peak voltage is twice as large as the 0-peak voltage? Owww. That makes my head hurt.
If you see the ridiculous of that statement (RMS level <> RMS level), then it must follow that you'll get half the energy for a half-wave rectified voltage, because a half-wave rectified voltage has half the RMS level of a full wave rectified voltage.
So Nigel maintains that operating a light bulb from 220V AC RMS would be twice as bright as operating the same bulb from full-wave rectified DC with the same RMS voltage because the peak-peak voltage is twice as large as the 0-peak voltage? Owww. That makes my head hurt.
If you see the ridiculous of that statement (RMS level <> RMS level), then it must follow that you'll get half the energy for a half-wave rectified voltage, because a half-wave rectified voltage has half the RMS level of a full wave rectified voltage.
And your 'conclusion' is similarly confused, as you're mixing VOLTAGE and POWER, which seems to be the common error through out this thread. Half the voltage means quarter of the power, it's hardly difficult - apply ohms law!.
I must admit I'm absolutely amazed that there's any confusion over simple basic electrics (not even electronics).
240V is 240V RMS - adding the diode makes it 120V RMS (only using alternate half cycles), and halving the voltage quarters the power.
You're confusing volts and watts.
I have to agree with that last line, but I'm afraid it's you who is confused, in this specific instance; you just seem to be looking too deep in to the technicalities rather than basic principles.
Forget the time scale, just stick to 50% duty cycle.
Imagine it's on for eg. ten seconds, then off for ten seconds, repeating.
The long term average over many cycles is then 50% of full power - can anyone argue that?
Again, you've leapt to POWER instead of VOLTAGE
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