Econometrician PM230: notes on the operation

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Christophe
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Econometrician PM230: notes on the operation




by Christophe » 12/02/07, 10:00

One thing to know about PM231 https://www.econologie.com/shop/wattmetr ... -p-20.html For all those who have already bought or are planning to buy it soon:

If you do not use it for an extended period of time (ie, it is not plugged into a socket by any device connected to it), remove the 2 memory batteries to extend the time of life.

If you have noticed other things that users should know, please share them on this subject.
Last edited by Christophe the 14 / 02 / 15, 00: 20, 2 edited once.
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dspix
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by dspix » 13/02/07, 12:31

Oi tudo bem...

Hello,

A colleague of work has given me his PM230 he bought on this site ...

After several rather curious tests at home, I made more thorough tests at my job ...

The conclusion is clear: this device cannot correctly measure low power on devices with cos phi <1.

Thus, if a 600VA transformer connected to a vacuum gives I = 320mA and cos phi = 0,28 for a displayed power of 19W,

A 30VA transformer always has empty, gives me a cos phi of 1 for a current of 100mA, and thus shows me a power of 23W ...

This last measurement is false ... the unit can not measure the cos phi in low current.

The same can be observed with fluorescent tubes, for example, which, when used with ferromagnetic ballasts, have a very out-of-phase current. The cos phi turns to 0,5 a 0,6 and sometimes less.

Ex: a lamp of 11W will be able to consume a current of 0,17A ... The power will not be of 39W, as I could read it on the post of the forum relating to the testing of this device.

But 230 * 0,17 * 0,47 = 18W ... So we are very far from the values ​​displayed on your forum... (0,47 is the cos phi of the tested lamp)



Finally, other tests carried out at home:

The PC with the ATX power supply stopped, only the mains filter is connected (capacitive load). The PM tells me 30mA (which is not necessary) but it also tells me a power 6W totally false ... with a cos phi of 1 ... Now, a capacitive load generates a cos phi that rubs the 0 ...

Even test with only the power supply of the scanner 15VA a vacuum indicates to me a power of 12W.

And by connecting both the transformer (inductive load) and the filter (capacitive load) I find myself with a measured power of 0W ... therefore below the threshold of measurement of the device.

The explanation is simple, by connecting an inductive load in parallel with a capacitive load, the currents compensate (delay and phase advance). And finally, the resultant current is lower with a better cos phi.

If the 2 measurements really indicated a power, I should have had 12W + 6W or 18W ... (the active powers accumulate).

With a purely resistive load (carbon resistance) of 10kohm, the PM measures a power of 5W, which is just because the cos phi in a resistance is actually 1.
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by ThierrySan » 13/02/07, 12:53

The PC with the ATX power supply stopped, only the mains filter is connected (capacitive load). The PM tells me 30mA (which is not necessary) but it also tells me a power 6W totally false ... with a cos phi of 1 ... Now, a capacitive load generates a cos phi that rubs the 0 ...


A capacitive load generates a cos phi that rubs 0 ?! Or 1 ?!
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by dspix » 13/02/07, 13:36

The cos phi of 1 is what the PM shows ...

The cos phi that rubs the 0 is what actually happens (phase shift between current and voltage close to pi / 2)
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by I Citro » 13/02/07, 15:30

Great comments ...
The PM230 to some limits ...
No product is perfect.

I have noticed that it could not measure very low consumptions like those of certain 220v diode lamps data for 1,3 W ...

On the other hand it is able to measure 3500W consos (like that of my dryer : Evil: , What competitors can not do ...
Last edited by I Citro the 18 / 04 / 07, 15: 53, 1 edited once.
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dspix
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by dspix » 13/02/07, 15:55

To be able to be as good in the low powers, it would be necessary that the device could have several gauges on the measurement of the current ...

A current of 160mA, it is hardly 1% of the full scale ...

This is one of the golden rules of instrumentation ... the more the measuring device is used in its full scale, the better the measurement is good ...

I do not know if this site has any means to intervene with the manufacturer, but if the device possessed 2 current ratings (1A and 16A) it would already be able to be more accurate on the weak currents ...
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by Christophe » 13/02/07, 18:44

Dspix wrote:I do not know if this site has any means to intervene with the manufacturer, but if the device possessed 2 current ratings (1A and 16A) it would already be able to be more accurate on the weak currents ...


Uh ... we have obviously no way ... but the problem arises with ALL econometers it seems to me since none are equipped with 2 calibres (or it is automatic but on those with less than 50 € I highly doubt it...)

As I told you by mail, the PM is not sold as a precision laboratory measuring instrument (so do not expect to get the performance of a oscilloscope or a Fluke at 800 € ... Or more) but as an energy meter over a "long" period and this last function it performs perfectly.

I would add that all energy meters sold at 35 € or less do not take into account the cos phi (to my knowledge) from where our choice on this product ... which was the best value for money.
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by cemoi » 17/04/07, 09:11

Hello,
Interested in purchasing this device, I would like to check that it is superior to this model sometimes found at Lidl's 10 €.
The specs of this one indicate an accuracy of "+/- 5% of the measured value +/- 10 VA" which does not seem terrible to me (if I understand correctly an uncertainty of +/- 10VA is added to the 'uncertainty of +/- 5% of the measured value so if a consumption of 10 W is measured, the total uncertainty is slightly greater than 10 W or of the same order of magnitude as the measured value).
What are the precision specs of PM 230? I did not find the record for download on this site nor On the Brennenstuhl site.
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by Christophe » 17/04/07, 09:49

Cemoi wrote:What are the precision specs of PM 230? I did not find the record for download on this site nor On the Brennenstuhl site.


Uh, I think you did not look very well : Cheesy: The data in terms of precisions are at the end of this page: PM230 power meter The notice does not give more.

I think the Lidl model has nothing to do with PM in terms of efficiency (no cos phi, no schedule, no dual schedule ...) but above all durability (I bought an unbranded Chinese econometer at 27 € who measured for ... 3 weeks and after he went "crazy" ...). Finally, brennenstuhl products are all guaranteed for 2 years.

But be careful in general not to expect from this type of device precisions of multimeters. Their primary function is to measure the energy over a longer or shorter term and not the instantaneous power.

ps: http://www.voilelec.com/vente/brocante.php they are objects? Some might interest me. I am doing a home lab.
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cemoi
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by cemoi » 18/04/07, 15:27

Christophe wrote:The data in terms of precisions are at the end of this page (...) The notice does not give more.
For me these are values ​​of measurement ranges, not precisions.

I think the Lidl model has nothing to do with the PM in terms of efficiency (no cos phi, no schedule, no bihoraire ...)
yes, take a good look at the "notice", there are two time slots, and the cos phi is displayed.

But above all to hold over time
Indeed at this price it may be "quickly disposable" this thing, especially since neither the manufacturer nor the model are specified.

But be careful in general not to expect from this type of device precisions of multimeters.

According to the information given above by dspix, I have the impression that this device is not suitable for a correct measurement of the conso of a computer and a screen in standby, and small electronic devices (transformers chargers IPod, modem, router).

Their primary function is to measure the energy over a longer or shorter term and not the instantaneous power.

How will the measurement of energy over a long period be less affected by an incorrect determination of the cosphi than the instantaneous power measurement?

I do not know, you have to ask the owner of the site, that I am not :|

While walking around the site I found this page which should interest readers of this forumbecause it includes many results of consumption measurements of household appliances, and information on the taking into account of cos phi by the EDF.
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