Using the Pico CM3 for 3 phase

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Kiwi
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Using the Pico CM3 for 3 phase

Post by Kiwi » Tue Oct 29, 2019 5:54 am

Hi,
when used on 3 phase what is the time resolution, I see somewhere 720msec per channel so does this mean to log 3 channels is 2.16 seconds, i.e. 3 logs @ 720msec apart ? (which is ok for our application).
Is the log the RMS for the 720msec or can you select peak AC current ?
Cheers.

Gerry
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Re: Using the Pico CM3 for 3 phase

Post by Gerry » Wed Oct 30, 2019 5:10 pm

Hi Kiwi,

The time resolution is as you describe (because the CM3 actually converts the reading to RMS, so you can't select peak AC current). However, just so that you are aware, as the current reduces to ward zero the time resolution becomes longer.

Regards,

Gerry
Gerry
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Kiwi
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Re: Using the Pico CM3 for 3 phase

Post by Kiwi » Mon Nov 04, 2019 1:49 am

Thanks Gerry,

Our application is for up to 15 CM3 loggers to log power use in 15 x 3 phase mobile dental clinics, we take them to remote schools (up to 200kms away) and occasionally we have power issues so we want to be able to remotely view what is going on.

Of interest we have already been using a PicoLog 1216 to simultaneously log 10 different power channels (3 phases, air compressor, dental suction, steriliser, instrument washer, air-con, hot water cylinder etc)

We use special CT’s that give an output of 0-2.5v DC so 25 amp AC = 2.5v DC. With the 1216 we can log all 10 channels simultaneously at 1 second intervals (1 second to log all channels). I think we can log even faster but it just uses more memory, likewise I think the 1216 will give PEAK as well so no need to be so time sensitive.

Main drawback to the 1216 is every day we need someone to access the recording laptop, end the capture, save the file and download as a 3Mb CSV file, and restart for the next day. I can't personally access the laptop remotely for a minefield of government IT restrictions and reasons. So I try to get the dental staff to do it, which can be hit n miss :-)

So we are looking to use a CM3 in each of the 15 mobiles, save it to a laptop, and to remotely access the data via the cell network. How hard could that be !

Final question, if set to record at the max rate, roughly how big is the CM3 file for 3 phase after 24 hours ? (just approximate).
Thanks,
Terry

Gerry
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Re: Using the Pico CM3 for 3 phase

Post by Gerry » Mon Nov 04, 2019 6:27 pm

Hi Kiwi,

To answer your question, after 24 hours of capture, from all 3 channels of one CM3 datalogger, at a rate of 1 sample per second, the size of a Picolog data file will be 1.5Mb.

What you are looking to do shouldn't be that hard to setup (cellular modems these days are effortless to use) but the cellular coverage may be the issue (in which case you may have to use something such as a lower cost version of this: https://www.satphone.co.uk/product/iridium-go-9560-satellite-wifi-hotspot/?leadsource=375698&keyword=&gclid=EAIaIQobChMI66fX25XR5QIVhrTtCh158Q3cEAQYASABEgJld_D_BwE&ppcsclkid=EAIaIQobChMI66fX25XR5QIVhrTtCh158Q3cEAQYASABEgJld_D_BwE&ppcstrkid=1502580530&ppcsu=xhg7f5djqrotinomllac).

Regards,

Gerry
Gerry
Technical Specialist

Kiwi
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Re: Using the Pico CM3 for 3 phase

Post by Kiwi » Tue Nov 05, 2019 9:32 am

Thanks,
we'll order a couple of CM3's and see how we go.
We have good cellular coverage, the mobiles have yagi (12dbi) directional aerials and when we set them up at the school we point the aerial in the direction of the nearest site.
One last question re the ethernet port, could we set up the CM3 straight from the ethernet port and into the cellular modem (without a laptop) and just get a stream of updating data which is captured by a base computer ?
I understand if there is a drop out we may lose data but if we can do without the laptop and use PoE for the logger then things get a lot easier for us.
Appreciate your prompt and informative replies.
Cheers,
Terry

Gerry
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Re: Using the Pico CM3 for 3 phase

Post by Gerry » Thu Nov 07, 2019 12:08 pm

Hi Kiwi,

GPRS does give you always on capability but you may have issues with drop outs preventing the software from confirming that the connection is alive. you could effectively poll the data but then we would need to know how fast you need it.

Could you tell us what the source of the mobile 3-phase power is?

Regards,

Gerry
Gerry
Technical Specialist

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