Purchasing correct equipment

Robert.Wall · 2020-05-14T13:17:50.711Z

Toein6647:

I am looking for a unit that records in real time and can download to a PC

The emonPi will certainly do that. Actually, it presents the data as a web page on your LAN, so a PC or phone or tablet can be used to look at the numbers and the graphs.

Toein6647:

Does your unit identify individual appliances or is that a bit of a sales pitch?

Given enough input channels and access to the cables, we can monitor individual circuits going out of your distribution board. But automatically identifying and separating out individual appliances from their demand profile is a Holy Grail that, as far as I know, nobody has been able to achieve with anything better than a very moderate degree of reliability. We don’t measure in enough detail to be able to do that automatically. Your eye, and a knowledge of what you were doing and when, followed up by a bit of detective work, is likely to be just as effective if not better.

This is why I asked about what you needed now and what you thought you might need in the future. You can add an emonTx to the set-up at any time - that would give you the 2 channels in the emonPi plus 4 in each emonTx you add, but if you know exactly what you might need in total, that might not be the most economical route.

For now, given that all you want initially is the total consumption, an emonPi with 5 V d.c. power supply and emonCMS software on an SD card (all included), plus an a.c. adapter to measure the mains voltage (for best accuracy) and a current transformer to clip on the main incoming cable, is what you need. And access to your WiFi (or an Ethernet socket nearby and an Ethernet patch lead).
You’ll need two mains sockets close to your incoming supply where the emonPi will go - one for its power supply and one for the voltage monitor.
You do need access to a single-core incoming cable - probably next to your meter - on which to clip the current transformer.

Toein6647:

we used to run a small business and the costs were high due to the equipment operating but now retired completely for a year so very little equipment running but the bills very similar?

My first thoughts are: First, what business equipment were you running, and can you estimate their consumption - it might not have been quite what you thought; and second, the most energy-hungry loads are usually heating. Those should show up readily in emonCMS when you’ve gathered enough data.

Toein6647 · 2020-05-14T13:21:41.724Z

Hi Robert,

Very many thanks for all the info I will order what you are suggesting

Regards

Ian

borpin · 2020-05-14T13:26:04.615Z

Robert.Wall:

You’ll need two mains sockets close to your incoming supply where the emonPi will go

I’ll highlight this as it is easily overlooked as a requirement.

Can you send a photo of your meter location and / or the Distribution unit?

If the wiring inside the distribution unit allows and you are confident in doing so, it is sometimes possible to put one of the CT Clamps round the cable for one circuit so you can monitor just that circuit.

Toein6647 · 2020-05-14T13:46:50.892Z

Hi Robert,

I will have to get a twin surface mount socket installed, I will get the front off the distribution board very soon and send on the internal image, bye the way as I in Southern Ireland can the software be configured to show Euros per Kw hr?

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Cheers

Ian

borpin · 2020-05-14T13:56:39.273Z

You might find you can get to the circuit wires as the Distribution Unit is quite large. However, you do need access to the mains feed from the meter as the CT clips round that.

Robert.Wall · 2020-05-14T14:13:37.301Z

Toein6647:

I will get the front off the distribution board very soon and send on the internal image

Do mind your fingers! Is the meter through the wall to the right of the board? I presume all the outgoing circuit wires are in that large trunking.

Toein6647:

can the software be configured to show Euros per Kw hr

I’m not an emonCMS expert, it will need somebody who is to answer that.

Toein6647 · 2020-05-14T14:41:29.759Z

Hi Robert,
That trunking is only for the heating timer/switch

Cheers

Ian

Toein6647 · 2020-05-14T14:53:07.543Z

Hi Robert,

Can you tell me what the Optical Pulse Sensor does, do I need one?

Cheers

Ian

borpin · 2020-05-14T15:00:33.426Z

Toein6647:

Can you tell me what the Optical Pulse Sensor does

It reads the flashing light on the front of the meter if you have one. Only really needed if you can’t fit a CT. Doesn’t give instantaneous load.

Robert.Wall · 2020-05-14T15:00:50.941Z

It counts LED flashes from your meter. Two points: First, it’s totally accurate by definition (even though it might not be!); second, you’ll only know you’ve consumed a unit of energy after the event, when a pulse comes in. The c.t. measures power, and will give you the information at 5 second intervals (by default - it’s usually fast enough.

Your main use for the pulse counter would be to calibrate the c.t. accurately.

Note that if you have P.V, it won’t help much because it won’t count exported energy.

Toein6647 · 2020-05-14T15:02:42.977Z

Ah OK were does it fit, on the meter or on the incoming cable to the distribution box?

Robert.Wall · 2020-05-14T15:03:10.519Z

On the front of the meter, covering the flashing LED.

Toein6647 · 2020-05-14T15:03:56.707Z

Many Thanks

Robert.Wall · 2020-05-14T15:05:44.750Z

So you’d need to get a cable from the emonPi through to the meter - and the supplied cable has a RJ45 plug fitted and the cable is approx 1 m long.

Toein6647 · 2020-05-15T11:17:05.127Z

Hi Robert
Me again! my meter is on the outside wall so at least 5 mtrs from the distribution box by the time it has gone up the wall and through the loft (bungalow) would an extension cable male/female RJ45 be suitable or would that affect the signal?
Ian

Robert.Wall · 2020-05-15T12:43:50.150Z

Given that it sounds a deal of trouble to run the cable, I’d wonder hard why I need the pulse sensor. The emonPi should be accurate to within a few percent – from memory you have about an even chance that it’s within ½% and about 80% chance that it’s within 1%, even though the worst case error is appallingly huge.

I’ve never tested that sensor with an extension, but I don’t see why not, if it’s only 5 m or so.
But I’d keep it away from the main cables if that’s possible. We don’t know what’s inside the sensor so we don’t know how sensitive it might be to interference if you run the cable all the way right next to the main tails from the meter.

borpin · 2020-05-15T13:10:51.205Z

I wouldn’t bother with the pulse sensor. If you want to be able to measure the overall use and a circuit at the same time, the emonPi has 2 CT inputs so you can just use a second CT.

Robert.Wall · 2020-05-15T14:48:42.943Z

borpin:

I wouldn’t bother with the pulse sensor.

Neither would I - except to calibrate against. And from what Ian wrote initially, what he’s looking for is large relative use or sustained use that he can’t identify. And I think being one or two percent out won’t have a material effect on that.

JJC · 2020-05-15T15:59:42.136Z

Hi,

I have an EmonPi with two CT as I have Solar, you can set the apps up to give any currency setup you want as the devisor will be the amount you pay for each Kwh. You can also set up an account on Emoncms.org as when you buy your EmonPi you will get enough “credits” for quite a few years usage and all your data is then up in the cloud (as well as on your own EmonPi This also means you can put the app on a smartphone and see the data from anywhere not just home. To get the ethernet connection to the distribution board I use a set of powerline adapters. As for adding a socket if you get on with USB charge ports on it this saves one socket

John

Toein6647 · 2020-05-15T16:04:19.199Z

Hi John,

Well that’s really interesting, what price are you looking for?
Could you explain the “credits” please

Ian