I did all of these AC calculations, but it was at least 20 years ago. I've mainly worked with DC since that time & I've always found DC a lot simpler. Speaking of which, I understand there's actually a way to run these MV bulbs from DC. I wonder if it's like is done with certain x-ray tubes and just using a diode to convert to DC, or more elaborate?
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** They use *wattmeters* that accumulate so becoming "Watt-hour" meters.Customers get charged for the actual energy used, not merely current over time.
The ones where I live look much like this:
The spinning disk will not move unless both current and voltage of the same polarity exist at the same time.
.... Phil
Back in Manhattan Beach, California, while living with a friend, The house had a single 120 vac feed, not the more common 120/120 240 vac feed. So his 1 KW Heathkit amplifier would draw a LOT of current.
I picked up a power company power factor correction capacitor. Heh, when we put that across the line, the watt meter would come to a complete halt.
Watt hour meters will read, properly, with an r+j impedance load. They get confused with an r-j impedance.
-- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com
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** Heathkit ? 1kW ??FYI, there is ZERO phase angle between the V and I drawn by an amplifier.
** Hope that is not some weed induced hallucination form the late 1960s...The only thought I have that connects is the power company, aware such shenanigans sometime went on, fitted a device to PREVENT the watt-hour meter ever going backwards. Easy enough to do, in the reduction gear chain for eg.
Piss the hell out of greenish coloured folk nowadays, with their roofs covered in acres of PVs.
.... Phil
Nope, never did weed or any other drugs.
-- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com
There are several Heath amps that put very nearly 1 kw on the outlet. The AA1640 comes right to mind, as it, in mono, makes 800 watts into 4 ohms. circuit losses of 200 watts or so does not seem unlikely.
My Harman Kardon Citation 16 draws close to 12 amps @ 120 VAC at full load, making 1,440 watts. Not that it has ever been driven to that extreme - but it is just possible.
Dynaco 416, Phase Linear 700, Crown CE1000. There are a good many brute-force amps out there, not accounting for quality, just force.
Peter Wieck Melrose Park, PA
This was an Amateur Radio RF amplifier.
3.5 to 30 MHz. SB-200-- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com
I don't know how accurate it was, but a few years ago I replaced the tubes in my Sb-200 amp. I wanted to see how efficient the amp was.
I had an el cheepo China meter that showed Volts, amps, watts. The volts did check with my Fluke meter.
With a bathroom heater the watts and V times A were vey close maybe because of the very small fan motor. When hooked to my amp and loaded to 600 to 700 watts RF out the watts and V times A were way off. One showed maybe 80 to 90 $ different depending on the loading. I took that to be the inductance of the transformer causing that.
I don't know enough AC theory to explain it if there is not more than a ZERO phase angle.
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** The PF of general electronic load is about 0.5 to 0.65.But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
The "true rms" value of a pulsed current is higher than a comparable steady sine current.
.... Phil
The reference was to the video where he used an unloaded motor. Then as you say, "current draw and power consumed off load is much lower". So how often do you run a motor unloaded and is it worth the cost of PFC. How often does a factory run a motor unloaded? Mikek
Ok I can see that , The meters are not really showing what is going on. I do understand the part about a 'true rms' not being the same as what most simple meters show when calibrated for a sine wave and not all kinds of non sine waves.
Just faulty thinking about the inductance of a transformer.
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** The simple mistake that most folk make is not knowing the definition of VA and hence the meaning of Power Factor.FYI: VA = rms Voltage times rms Current.
and PF = true power / VA
For example,
a true rms clamp mater allows a sparkie to measure the VA of a load but he would need a "watt-meter" to find the true power.
Plug-in meters that do both cost very little nowadays.
.... Phil
Ok, so I picked up a Kuman Electricity Usage Monitor. For anyone not familiar, it shows KW used, current V and I, some other things like a cost calculation, etc. I plugged the 175 W mercury lamp into it and here are the figures I got after letting the system run for 8 hours, 35 min:
1.77 Kwh 209.8 W 0.19 cost 2.018 A 0.84 pfcSo, inputting my Kwh rate beforehand, it's showing ~19 cents per 8 hour period.
I have no idea if these figures are correct and probably won't until the electric bill arrives and/or I ever came across a scope. The device had good ratings and most folks seemed satisfied, which was the main reason I purchased it.
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