Hi guys. Any idea where I can grab a day sheet for pulse outputs on EDMI meters. If a certain ct ratio exists there is a set pulse for that or is there a calculation one can use to ensure the correct pulse output is selected. Thanks in advance.
Welcome, Gareth, to the OEM forum.
To be honest, I don’t understand your question. Which model of EDMI meter do you have, and have you tried the usual suspects - principally EDMI themselves, for a - did you mean data - sheet?
What’s going through the back of my mind is you have an industrial installation, not a domestic one, and your meter has current transformers instead of a direct input, which is the case for every domestic meter that I’ve come across.
Even if that’s the case, the meter’s pulse output will almost certainly be scaled internally, and the pulse rate will be shown on the face, or a label, or if it’s an electronic meter, via an option in the display. I’d be surprised if you - presumably you are a consumer - have any choice regarding the scale factor for the pulse output.
I’ve just looked at the data sheet for the Mk31 meter, that says “Meter Constant: 1600imp/kWh or 3200imp/kWh” - but I would be fairly certain that this choice is vested in the meter owner (your supplier) and not you.
If you are putting the pulse count into emonCMS (say), that’s where you scale it to represent kWh, according to the meter constant.
Thank you very much for your in-depth response.
You are spot on. The problem we were facing is that this meter is in a commercial installltion. There is a constant on the face that says 1000 impulses / kWh. That is for the flashing led on the front panel. Problem we encountered was that were were not getting the correct consumption usage. We are using our own Pan 42 with 800/5 ct using our own Centrica bridge that uploads data wirelessly to the cloud but when comparing our plus the utility there was discrepancies. Turns out the meter was set to a 400/5 ct ratio but only using 200/5 ct on the main supply.
The meter has pulses outputs and this output is directly proportionate to the ct ratio. A ratio of 200/5 gives automatically a factor of 0.04 kWh/ impulse. Double the cut ratio and you double factor. Apparently there is constant for this and that is the spread sheet I am looking for. I hope this makes sense.
If you’re using a 200:5 c.t and the meter is set up for a 400:5 one, then you’re going to be getting twice the secondary current that the EDMI meter expects and so the meter will be emitting 2000 impulses / kWh.
Is the question now, how do you calibrate your Pan 42 to use a 800:5 c.t?
I see the data lists 600:5 & 1000:5 c.t’s, but I can’t see anything about telling the Pan 42 which it is using, but that must exist either inside the unit itself, or it could be in the “cloud” application. I think that’s the place where I’d look first.