How to find watt hour constant in PM9P schneider electric meter

Hi I am trying to read pulse output of PM9P meter. Can anybody help me to find watt hour constant here from data sheet.

is it 1 pulse=10KWh also for power calculation what will be the T is it 50ms?

Welcome Soni to the OEM forum.

It would appear from the instruction sheet that the pulse calibration is configurable in software, so unless it is written or printed on a calibration label, the best you can do is wait for the reading to change, note the reading and count pulses until the reading changes again - clearly the more pulses you count and the bigger the difference in readings, the more accurate the result will be.

This is a common problem with electronic meters - even meters of the same make and type can be set up differently according to the specification of the meter owner (normally, the electricity company).

Thank you so much Robert for your answer.

if you see above image (snapshot from instruction sheet) they are giving an option that timing of pulse can be changed like 50 ms/ 100ms . So it seems from here I can find time difference between two pulses.
Like here if I take 50 ms as pulse duration then it means 0.05sec would be the time difference between two pulses. Hope I’m thinking in right direction!

The second panel lets you choose any of:

1 pulse per 100kWh
1 pulse per 10kWh
1 pulse per kWh
1 pulse per 0.1kWh

I think the third panel merely controls how long it will light up the LED for at each pulse.

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Erm… No, not really. All that does is sets the absolute maximum pulse rate.

Let’s say it is set to 10 kWh per pulse, and you’re taking a current of 167 A per leg (at 2 × 120 V). That’s 40 kW, so you’ll have one pulse every 15 mins.

I’d suggest that for normal domestic use, only the most sensitive setting would be useful. If the meter was intended for domestic use, it’s likely (no guarantees) that’s what it has been programmed to. But you still need to verify that.

(Many UK meters are 1 pulse per 1 Wh.)

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Thanks for correcting me. Will explore it further.
Meanwhile, I got a quick question regarding UK meters (1 pulse = 1 Wh), i think you are referring to Elster meter A100c. I mentioned my question in picture! Will really appreciate if you can throw some light on it…meter

Given it’s a 3-phase meter, and in the US, three phase is very rare in residential or even light commercial environments, I’d guess he’s either in an industrial environment, or is trying to use a 3-phase meter in on a split-phase service.

10Wh/Pulse is the same as 1 pulse / 10Wh which is an order of magnitude higher resolution than your most sensitive setting above of 1 pulse / 0.1kWh (i.e. 1 pulse / 100Wh).

1000 pulse/kWh is the same as 1 pulse per Wh which is an order of magnitude more sensitive again.

The pulse duration setting is unrelated to that. You should set that long enough (50, 100, 200, 300 msecs) to ensure that your pulse-reading h/w can detect it as a pulse. An inevitable side effect of that setting is to limit the maximum pulse rate. But even at the meter’s most sensitive pulse rate (1 pulse per 100Wh) and longest pulse duration (300 msecs) it can still do one pulse per second which I think would require a 360 kW load, so quite a lot of power.

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Thanks for the clarification, but on this meter why they have mentioned both things 10Wh/Pulse and 1000pulse/KWh. Can we pick any for real time energy calculation ?People recommend to use 1000pulse/KWh (ie. 1 pulse per Wh) not 10Wh/Pulse. Is there any particular reason?

I guess it’s convention or personal preference. It’s like asking why is vehicle’s fuel consumption sometimes given as miles per gallon in the Imperial system, and litres per kilometre in the metric system. Higher is better in the first, lower is better in the second.

Sorry, I missed that both markings were on the one meter. I can’t explain that. My only guess is that one overrides the other and they forgot to cross the other out.

With your original Schneider meter (that I assume you own and configure) you can choose between four pulse rate settings. With your Elster revenue meter the pulse rate will be fixed by the provider.

Pulses are not an ideal way to monitor usage, the best they can reveal is average power usage over the variable pulse interval. The longer that pulse interval the more blurred it all becomes. If all you want to do is read your revenue meter once per day without going outside to visit it, then they’re pretty effective but if you want to get a precise picture of when loads are coming on/off you really need to be able to interrogate your meter at a fixed time interval.

As an extreme example, if you consider your Schneider’s coarsest setting of 1 pulse per 100kWh that would work out at roughly 1 pulse per month at my house so wouldn’t be much use for determining anything.

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That sounds like a use case for a sub-station or switching yard. i.e. a distribution feed for a city or town.
e.g. the town I live in. Although small, (population ~900) it sees a peak load of ~2.2MW during summer.

Thanks guys for your response. It was indeed useful, I got more clarity. Appreciate everyone efforts!!