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.
Hi Robert. Sorry for not getting back to you earlier. The pan 42 requires an input. So we input what the size ct we are using and it will in turn reduce its own calculations. Without buying take off heads and software it’s difficult to determine what the pulse weight has been programmed too. So currently we have a 2 wire system connected to the relay output of a A1700 Elster meter. My bridge is seeing a good influx of pulses. The question still remains, what is the pulse value. What does each pulse represent. If I take my max kw to be 541kw convert that to kWh = 541kwh /3600 so a pulse at 1 sec intervals would equate too 0.075. It’s all confusing. If only the button on the meter could tell us what the pulse value S set too life would be a whole lot easier
I think you need to be careful with your spell-checker - there appear to be a lot of wrong words that are making the description less clear.
Where does this meter fit into the picture?
Earlier you wrote
Presumably, that is sending real numbers, not pulses. So is the calibration/scaling of that which you might be questioning - “might” because it appears two sources disagree, and you don’t appear to have a reference to arbitrate between them.
I think there’s a bit of a mix-up there too - don’t you mean the calibration is proportional to the c.t. ratio? Let’s get the thinking straight: The calibration of the meter’s kWh display is proportional to the c.t. ratio. The pulse count is in turn proportional to the kWh recorded. A meter set for a 400:5 c.t. will record twice the power/energy as one set for a 200:5 c.t. given the same load. Are you really saying you are, or were, paying for twice the energy that you’re using? If so, that’s seriously worrying.
Which brings me to this
What is the present state of your metering? (Remember, all I know about your installation is what’s written here.) I think you’ve got to do it the hard way: note the meter reading of kWh, wait for some period of time while counting pulses, then note the reading again, and work out the pulse count per kWh from that.