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Author Topic: test equipment  (Read 74995 times)
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« on: June 06, 2010, 05:21:26 AM »

thought i would start this section out with what i have found to be a relatively inexpensive, accurate,
and effective means of measuring the factors needed to determine BSFC or how much fuel are we consuming
per kwatt hour of  electricity produced.

in the beginning i worked with clamp on amp meters, and a volt meter, and used a resistive load in an effort to
keep power factor to as near unity as possible. it soon became apparent that this is problematic.
clamp on meters can be very accurate, and can also shift about, volt meters generally are very accurate, but
trying to read both amps and volts at the same time, then multiply the two, especially when a resistive heater load
shifts about as a draft comes across them, and also then having to time the test to get down to kw/hrs is just not
going to get one accurate and repeatable test results.

i started to look for a solution, when i came across the GE kv series digital residential watt/hour meter


this ebay unit is meant for 3phase, but is indicative of what a single phase unit also looks like.

what i found was on the front there is a optical port for programming the head, which we can talk about later
and also a small lever actuator on the lower right side, this switches the readout to read things like voltage per phase, amps per phase
and a few other things.

beside the lever is a small push button (momentary) that is inaccessible from the outside, but clearly visible under the lexan cover.
when we depress this button the head goes to diagnostic/test calibration mode. i just drilled a hole through the cover to access and depress
the momentary switch.

in this mode the unit will measure power in watt/hours, running an genset now until one reads out 1000watt/hrs will give you an accurate
measure of a kw/hr produced and consumed by the test load, no matter how that load might shift about over the length of the test.
now we don't need an amp meter, volt meter and a stop watch, we simply run until we get 1000, 2000, or whatever test we want.

this leaves us with only having to log and read out how many grams of fuel were consumed per 1000watt/hrs produced.

the resulting accuracy is very high, and incredibly repeatable.

one would need a meter box to mount the meter head of course, and there are suitable and very inexpensive options available at the box
stores to provide for either a dedicated box or a combination meter/breaker panel (which i use and it cost me 34 bucks)

the meter heads can be bought on ebay from time to time for less than 50 bucks, the meter box for 34 or less, and a digital gram scale can
also be had for 25 bucks or so, for a complete capability of getting very accurate testing for a bit over 100 bucks, and

the meterhead is useful for your finished unit, in that it will track accumulated kwatt/hrs as well or course which is nice to track service intervals.

in my next installment i will talk about how i measure and correlate recovered waste heats and factor them to the amount of fuel consumed
and against kw/hours of electricity produced.

bob g
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« Reply #1 on: June 06, 2010, 07:42:36 AM »

I got to see Bobs meter, it is pretty nice.
I have a UEI meter that has optional jaws, reads volts and amp at the same time.
Also has HZ, PF, Temp, and more.
Around 100 bucks.
Good if you need to pick up a meter.
I've never seen another meter that read volts and amp at the same time.
« Last Edit: June 06, 2010, 07:47:46 AM by WGB » Logged
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« Reply #2 on: June 06, 2010, 08:20:13 AM »

the advantages of having a combined meter that will read out watt/hrs accurately will become apparent as we move forward
with measuring heat recovered.

if we connect the prime movers heat exchangers to a storage tank, that is moderately well insulated so that we can measure heat gain
without losing any more than we have to.

we can then add water to the tank measured in gallons and calculated by weight in lbs

the water will also need to be at or above room temperature, any gain in temp due to below than ambient temps is cheating. Smiley

we then start the unit, and allow it to operate until it has become thermally stable, tstat flowing, and with a fixed load that is
at the level we want to test at (in my case i test at full rated load)

we take a temp reading at the start of a watt/hr test, and then run the unit until we have accumulated as many watt/hrs as we like
2 or 3 kwatt hrs is generally adequate, but going further increases the accuracy and real world results of the test.

at the end of the test we reread and log the tank water temperature, and calculate the temp gain in degree's F
multiply the gain by the lbs of water in the tank and we have the total recovered btu's from the recovered heat.

to this total heat recovered in btu's we take the kw/hrs generated and multiply by 3415 to convert the electrical to btu's
add both together to get total btu's produced.

we then look to the amount of fuel consumed and calculate how many btu's of fuel was consumed

divide the btu's produced by the btu's of fuel consumed and we have the units overall efficiency.

this test should be ran a minimum of 3 times to make sure of the repeatability of the results, if they repeat we know
we have a stable and reliable result.

to get the data in order to calculate this result we need the GE kv watthour meter, a gram scale and a thermometer
that make for 3 things to keep an eye on, rather than several more if we use separate clamp on meters, and a stop watch
which becomes far to cumbersome to get stable results.

further testing we can split out the heat gains from the cooling system, and from the exhaust, and perhaps the engine oil
and other heat sources, then using accepted ratio's we can get a relative efficiency for each exchanger in the recovery of the
otherwise waste heat. having this information allows us to have some idea where we are doing a good job of heat recovery
and where we might improve the process.

bob g
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« Reply #3 on: June 06, 2010, 05:13:19 PM »


Those heads look like just what we've been looking for !

Do you have any more information on those meter heads ?
The ones on Epay seem to all be three phase, useless for single phase service guys.
Or are they convertible ?
There seems to be a dozen different models available...
I'd hate to waste my money on a model that doesn't have all the feature that you describe.

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« Reply #4 on: June 06, 2010, 06:21:32 PM »

i have a pdf file somewhere that shows what these meters are capable of
iirc it is over 200 parameters that it can measure and display with proper programming

i will look it up and post it, soon as i can find it.

the meter that i know works is the GE kv series, it will look just like the 3phase unit in the ebay add
but made for single phase use.

they are not convertible to my knowledge.

they also come up on ebay with some frequency, i picked up two more in the last 30 days
one for a friend and the second for my test cell

bob g
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« Reply #5 on: June 07, 2010, 07:53:06 PM »

couldn't find the pdf, but found the following




here  is the one i was looking for!


also a company called "austin international" will program these meters to read out anything we like from the list
of available measured data. i am told it takes them about 15 seconds to do so, so i would expect that it isn't terribly expensive.

bob g
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