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Author Topic: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,  (Read 302933 times)

TinselKoala

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #345 on: September 06, 2014, 06:42:01 PM »
Hi Tinselkoala,

The Rigol scope is only a day old and so I am still learning its operation.

The differential probe has x20, x50 & x200 selections. I kept the x200 setting as I cant make the comparison with the x10 ground probe, exactly as you requested.

The previous shot before was done quickly as to not disturb my setup, henec the use of Chl2 & Chl3. The rigol measurement functions are over whole cycles so any display that shows less than a whole cycle results in blanked fields.

The phase shift according to the measurement function is 0.865deg.

When I tried to increase my vertical resolution from 20V to 10V there was an overange situation.

I tried the setup on my old Owon scope and set the max resolution I could, and measured 10us (approx 0.2deg) skew between the probes.

Which ever one you take,  0.865deg or 0.2deg  the skew is under a degree and so has little effect on the AxB (VxA) function computation.

Barry


Heh.. Now I'm convinced! Thanks for taking the time to do that. I can believe around 1 degree of difference between the active and passive probes at that slow frequency, and it will be the diff probe lagging of course. It might be interesting (but not really relevant here) to repeat that comparison at a much higher frequency to see if the scope's measurements of the shift changes at all. I would expect the phase angle between the Diff probe and the passive probe to increase with increasing frequency.


So here you've compared the Differential Voltage probe with a passive probe, right? And you've shown that the phase shift is very small. That's great! Now you should do the same thing with your current clamp probe, comparing the signal from it and from a passive probe across a current-viewing resistor in series with the circuit you are measuring with the current clamp.
 
Really, we want to see if there is a phase shift between the current clamp probe and the differential voltage probe. So by comparing both of them separately to a standard (the passive probe) you can get an idea if there is a shift introduced by your measurement.
 
I'm convinced that the shift from the Diff probe is small compared to the passive probe, but even such a small shift will have a measurable effect on the power function when near 90 degrees.


So if you could please do the comparison between the Current Clamp, and the passive probe looking at a CVR, then we'll know for sure that your measurements aren't introducing any phase shift into the computation of the power function.


I'm taking for granted that you have properly adjusted the compensation caps on your passive probes, etc.


Again, thanks for taking the time and trouble to perform these calibrations. I'm really jealous of your new scope; I wish I had a modern DSO in my lab to play with. In a pinch I can borrow a high-end Tek scope but it's kind of a hassle, involving 4 or 5 hours of driving.
 :-\


--TK

Void

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #346 on: September 06, 2014, 06:42:02 PM »
...
« Last Edit: September 06, 2014, 09:18:49 PM by Void »

TinselKoala

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #347 on: September 06, 2014, 06:51:08 PM »
@listener191:
On the Owon scope, you have the baselines set 2 minor divisions apart vertically. If you look where the zero crossings are you can see that if the lower trace were raised up 2 minor divisions to compensate for the baseline difference, there would still be one minor division vertical separation at the zero crossings. There is a measurable shift shown on the traces on the Owon scope.
For the best visual quantitative interpretation, and even for proper math computations on some scopes, both channels of concern should be set to the _same_  center graticule baseline, very accurately. If you want to separate the traces for some reason, like qualitative examination of waveform shapes or etc, _please_ set the baselines directly on major graticule markers, to aid in visual interpretation of the traces.

Also it's a lot easier to read the thread if you limit your images to under 1024 pixels wide!


listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #348 on: September 06, 2014, 07:37:38 PM »
Hi Tinselkoala,

As I said previously to Farmhand, I have already posted details of the current clamp and it shows no appreciable skew.

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #349 on: September 06, 2014, 07:40:56 PM »
Hi Void,

No the switching arrangement is the one I posted not Marios. Mario uses two switches on his original scheme because he uses a sound card to generate the pulses and he could not mix the channels onto a single bidirectional switch.

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #350 on: September 06, 2014, 08:03:50 PM »
Hi Void,

I have added the transformer to the circuit, so it should be clear now.

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #351 on: September 06, 2014, 08:13:45 PM »
Hi TinselKoala,

Attached are scope shots of shunt monitored current versus clamp monitored current and shunt monitored current against voltage.

As you can see, my current clamp does not skew phase.

Barry

Hi Tinselkoala,

I stand corrected, I made the check on the current clamp at your request not Farmhand.

Barry

Void

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #352 on: September 06, 2014, 09:19:54 PM »
Hi Void,
I have added the transformer to the circuit, so it should be clear now.
Barry

Thanks. I have deleted my previous post so as not to confuse anyone
with the wrong switching/cap arrangement.
All the best...




listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #353 on: September 07, 2014, 05:03:45 PM »
All,

Not wishing to mislead anyone, I discovered that I had my voltage probe across the switches,  instead on the source input. Just forgot to put it back after looking at transients across switches!

Having corrected the monitoring I changed the 6uF cap to 4uF to get the greatest V & I phase shift. The best I could achieve was approx 60 deg.

Looking at ratios not absolute measurements, for the source I have about 52.8W forward and 37.6W reverse (peak). The average power is 7.03W

For the load the average power is 6.21W 

So I have not got close to replicating the Babcock Murray results yet.

Barry
 

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #354 on: September 07, 2014, 09:06:55 PM »
Attached are a new set of scope shots which now correcty show the best I have been able to achieve.

3.21W average input for 2.84W average in the load.

V & I phase 72deg.

Cap is 4uF and this restricts the forward and reverse current considerably. Increasing value increases power in load but reduces V & I phase shift and hence reactive power.

Not sure that this arrangement will achieve a PF close to zero.

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #355 on: September 16, 2014, 07:26:01 PM »
All,

After trying many schemes, the parallel charge series discharge scheme with an added shunt cap across the source transformer secondary, appears to provide the correct conditions.

The switching does not have a gap between charge and discharge  so the waveforms are not exactly the same as the Babcock Murray ppt presentation. My setup is in a different configuration at the moment, so I will have to make changes again to try this out.

Barry


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listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #356 on: September 28, 2014, 09:27:00 PM »
All,

After experimenting with various schemes, I eventually came up with a charge push scheme that uses an additional 115V (but even better results with 230V) winding, to supply an in phase half sine push to the cap after charging. This allows the cap to discharge just after the peak of the half sine and allows an average return power equal to the average forward power through the load. The attached were taken using dual 115V windings. The attached shows 1.58W average power (differential) from source and  8.07W average in load.

Use of a 230V push winding allows larger caps to be used for example 150uF, and the best achieve with the scheme so far is about 30W averag in load for 4W average source power (differential).

Barry   

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #357 on: September 28, 2014, 09:33:51 PM »
All,

Attached is a shot of the load voltage/current and power measurements for the latest trasnformer setup with a 230V push winding. The discharge waveform now has almost equal area as the charge waveform. A further improvement might be to phase shift the push sine slightly, so the peak is on the charge sine falling edge. This would reduce the fall off on the discharge pulse trailing edge.

Barry

listener191

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #358 on: September 29, 2014, 02:31:44 PM »
All,

The 26W load average shown in the previous post is being supported by 42.5W average on the primary. The cap charge and discharge with push is clearly seen as forward power on the primary, with no sign of any power return.

The unloaded transformer draw is about 2.5W

On the secondaries the charge/discharge power averages to 3W or so over the two half cycles.


It remains to be seen if the return power truely manifests as negative torque on a generator.


Barry

popolibero

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Re: COP 20.00 (2000%) Times, Reactive Power Energy Source Generator,
« Reply #359 on: September 30, 2014, 07:05:13 PM »
Hi Barry,


excellent work. I'm working on the generator side of things, but am waiting for a new one to do some better testing with it.


Mario