Building Reserve and Using KWH

[DanS26]

Pretty cool, and cheap. A number of such meters have been worked into equipment
here. Whenever I get an AC watt meter, I connect a big cap to draw current with a
zero power factor. A good meter reads zero, just multiplying the A and V will be wrong.
Bruce Roe

Their 6 in 1 meter indicates the PF......for $21 its a good deal........

https://www.amazon.com/DROK-Frequenc...ef_=ast_sto_dp

[bcroe]

I use these little meters all over the place, they are accurate and inexpensive..........

Pretty cool, and cheap. A number of such meters have been worked into equipment
here. Whenever I get an AC watt meter, I connect a big cap to draw current with a
zero power factor. A good meter reads zero, just multiplying the A and V will be wrong.
Bruce Roe

[J.P.M.]

I use these little meters all over the place, they are accurate and inexpensive..........

https://www.amazon.com/drok

Price looks right. How did you verify their accuracy ? Any accuracy number estimates ?

Thanks in advance.

J.P.M.

[DanS26]

I use these little meters all over the place, they are accurate and inexpensive..........

https://www.amazon.com/drok

[J.P.M.]

That is what I needed, thanks. I see my Sangamo meter (originally used on this 70s house)
has a 7.2 at 4 o'clock position, which would equal 138.88.. revolutions per KWH. My best
estimate had been 144, but not done with great precision. 138.88 would correspond to 35 rpm
(really honking!) when the array peaks and nothing else runs, just about what was observed.

I have also done the stop watch thing, but also used the Kill-A-Watt meter for totals on cycling
stuff (fridge). Have also wired a disc meter in series with a double breaker output for 240VAC
stuff. With several disc meters here from varied sources, guess I now have the means to check
them out. Bruce Roe
ENEmeter.png

You're at least most welcome.

Unless you advise you need more info, I'll cancel my walk down memory lane with my notes.

Respectfully,

[bcroe]

. As I seem to recall, my old rotary meter constant was 7.2 which meant that 7.2 Watt-hours of energy have been expended for each complete dial revolution - at least when it got manufactured. Your meter may have a similar constant. I believe the meter constants are often printed in the lower left (~ 4 o'clock) position of most of the old rotary meters. 7.2 is a common one for old G./E. meters but they vary a lot.

For my steady state energy appliance use estimation, I checked the difference in dial rotation speeds/times with most everything in the house off at the circuit breakers, particularly cyclic appliances like fridges and measured the difference in rotation times 100 disk revs with a stopwatch when various "semi" known things got turned on like a 100 W incandescent bulb, a spot heater w/ 3 range settings, etc. and got numbers that seemed to make sense.

That is what I needed, thanks. I see my Sangamo meter (originally used on this 70s house)
has a 7.2 at 4 o'clock position, which would equal 138.88.. revolutions per KWH. My best
estimate had been 144, but not done with great precision. 138.88 would correspond to 35 rpm
(really honking!) when the array peaks and nothing else runs, just about what was observed.

I have also done the stop watch thing, but also used the Kill-A-Watt meter for totals on cycling
stuff (fridge). Have also wired a disc meter in series with a double breaker output for 240VAC
stuff. With several disc meters here from varied sources, guess I now have the means to check
them out. Bruce Roe
ENEmeter.png

[J.P.M.]

I was wondering if anyone knew, how many revolutions of a spinning disc meter, equal one KWH?
My estimate is somewhere around 150 revolutions. I see a lot of calibration marks on the disc,
wonder if they serve for factory calibration? Bruce Roe

You're going to make me dig into my archives/notes. As I recall, there was a meter constant in the lower right side of the old dial meters that was used to find what you're looking for. Using that and a stop watch was a good way for me to get definitional info on steady state draw for appliances/HVAC equipment and even kill-a-watt meter comparisons. The numbers seemed to work out and make sense.
I'll root around and see what I can find. Give me a day or so.

As I seem to recall, my old rotary meter constant was 7.2 which meant that 7.2 Watt-hours of energy have been expended for each complete dial revolution - at least when it got manufactured. Your meter may have a similar constant. I believe the meter constants are often printed in the lower left (~ 4 o'clock) position of most of the old rotary meters. 7.2 is a common one for old G./E. meters but they vary a lot. I usually used 100 revs to measure appliance usage and did the measurement several times. The method seems good for steady state operation but is mostly useless for guessing at startup transients or power factor penalties.

For my steady state energy appliance use estimation, I checked the difference in dial rotation speeds/times with most everything in the house off at the circuit breakers, particularly cyclic appliances like fridges and measured the difference in rotation times 100 disk revs with a stopwatch when various "semi" known things got turned on like a 100 W incandescent bulb, a spot heater w/ 3 range settings, etc. and got numbers that seemed to make sense.

For things like the A/C w/ 2 electricity draws, I figured out the compressor and air handler drew a total of something like ~ 6,000 W at steady state conditions but, as I implied above, I don't have my notes handy. Anyway, I checked the air handler w/a kill-a-watt meter at 842 running watts. I have that because I had to replace the air handler motor a couple of years ago and I have a dedicated kill-a-watt meter on the blower it to record approx. A/C system run time.

[bcroe]

I was wondering if anyone knew, how many revolutions of a spinning disc meter, equal one KWH?
My estimate is somewhere around 150 revolutions. I see a lot of calibration marks on the disc,
wonder if they serve for factory calibration? Bruce Roe

[bcroe]

. A non vented electric clothes drier would be the
other item, except they are pretty small. Bruce Roe

Today I see a 7.4 cu ft heat pump hybrid unvented electric clothes dryer, seriously considering
getting one. There have been small unvented ones, but this one is full sized. I always hated
blowing all that heat outside, and the vent leaks plenty of air the rest of the time. Whirlpool.
Bruce Roe

[bcroe]

. Here's a peek inside......dual MPPT.....hinge on side.

That looks great, I went and opened the cover of my unpowered standby Fronius for the
first time, and it looks just like that. Apparently 2 inverters the same size, I knew they
shut one down to increase efficiency for light loading. The whole thing made possible by
the development of the microprocessor (control) and power MOSFET transistors (muscle),
not to mention economical solar panels. I had used them and IGFETs, but now I guess
silicon carbide transistors or the like have taken over.

Just amazing how something that light and cool running can handle that much power.

I looked at the bottom section, looks like the fuses are connected to the plus red leads, so
I guess that means it is set for negative ground. I think this one came with fuses, my
originals had shorting slugs. Bruce Roe

[DanS26]

So, show us the pictures. Does it hinge open just like the bottom section? Bruce Roe

Here's a peek inside......dual MPPT.....hinge on side.


IMG_0684.JPG

[bcroe]

Being cautious is good, a 60W incandescent light bulb should bleed them in a timely manner

Incandescents are more efficient bleeders, because the resistance drops as they cool
for near constant current. For our 400VDC stuff you might need this. Bruce Roe


PVtestLt.JPG

[Mike90250]

Generally, those big caps, are on the battery wiring, and the controller internals bleed residual voltage down in half an hour, which is why inverter cables spark at initial hook-up.

Being cautious is good, a 60W incandescent light bulb should bleed them in a timely manner

[bcroe]

I couldn't help myself and opened up that big upper transformer box a few months ago just to see what was inside. Lots of big caps that I don't think one would want to short with screwdriver before removing. Bleeding those big boys off with a resister would make a lot of sense.

IMO very beautiful engineering inside.....I especially liked the active cooling design.

So, show us the pictures. Does it hinge open just like the bottom section? Bruce Roe

[DanS26]

...............When they do fail, I will no longer hesitate to pull them apart and see if DIY repairs are possible.
My hope is to replace all hard stressed caps, being prepared to do the same later for the ones
on line. Could be the failure will damage beyond repair. Meanwhile, I have one backup inverter
mounted close by, all I need to do is move over the power wiring (conduit already connected) to
put it in service...........

I couldn't help myself and opened up that big upper transformer box a few months ago just to see what was inside. Lots of big caps that I don't think one would want to short with screwdriver before removing. Bleeding those big boys off with a resister would make a lot of sense.

IMO very beautiful engineering inside.....I especially liked the active cooling design.