Counting operating time


For my pellet stove I’d like to monitor my pellet consumption in real time. My idea is monitoring the time a feeder screw motor is operated to compute the quantity of pellet burned by the stove.

Question : is it possible to count the amount of time a device is operated, wether using a CT or voltage detection ?

Thanks for your ideas.


Is the power to it hard wired or a plug?

Welcome to the OEM forum, Matthieu.

Do you want the time to go into emonCMS (or similar?) I think it might be easier to count revolutions of the feed screw, because that will give you a direct measurement of the quantity - always assuming the pellets don’t run out.

You can do that either with a commercial proximity detector, with a magnet on the shaft going past a reed switch, or with a reflective optical sensor. Without knowing exactly what the feeder looks like, it’s hard to say which would be the best. Optical might not be a good idea if the pellets create a lot of dust, and a reed switch might have problems with vibration.

If the feeder is “industrial”, then my inclination would be to use a proper industrial inductive proximity sensor to detect a metal flag on the shaft - or maybe bolt heads on a coupling? Power might present a problem, because those are likely to require 12 V or 24 V d.c. They are not cheap, but reliable.


@borpin I can access the wires. The real deal I guess is wether the software is able to count the time the device is operated and how.

Thanks @Robert.Wall !

The feeder is driven by a small 230V AC motor (probably 100W or so).

The motor is directly hooked to a speed reducer, there is no easily accessible moving asset. That’s why I wanted to measure the time it was operated.


Since there is a speed reducer behind the motor, counting the time the motor is operated should be roughly the same as counting the amount of revolution, isn’ it ?

Sounds like an ideal candidate for the emonCMS Input on-time function.

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That’s probably what I was looking for ! I can’t find any documentation mentioning “input on-time”, could give me some pointers to it ?

Txs !!

I wish I could. But I’ve never actually used it. (just know that it exists in the emonCMS “Input”
pull-down menu)

I’d forgotten about on-time. My thinking was: the quantity is proportional to time if the speed is constant. OK, it should be. But also, if the calorific value of your pellets is constant, then the amount of heat you get is directly proportional to the pulse count. And emonCMS can directly relate pulses to kWh.

This might be of some help:

I can’t believe there is nowhere to find any documentation on that setting. I have to say that while the hardware looks nice and promising, the software lacks of everything.

The learning curve is steep, the interface is nowhere from user friendly, the documentation is basically non-existent appart explaining some ready made receipts for some popular use case.

There are no demo versions, no dummy sensors to help understand how the cms works (when one gets it working by installing it himself).

It’s not possible to get an idea of what’s possible and what’s not. The software doesn’t look so open to other data that the sensors sold on the website. For anything else you must develop some code to make it fit to the cms.

I’m really hesitant to put any money in this project.

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@pagaille It is an open project. You are more than welcome to contribute. You’ve not paid anything for it. As ever, it is a tool which might or might not fit the job.

Sorry if it sounds rude. I’m an open source project advocate and I don’t want to complain if it the project doesn’t fulfil my need.

My point is that it is really difficult to know it it will to the job or not, and that there is no doc, which is strange for such a mature project.

Regarding the money, buying the hardware makes you contribute to the project, right ?

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Not having a device that switches on and off at fairly short intervals, I used my PV systm’s time importing and exporting as the values to track the on-time function. Plotting them on a bar chart yielded:

The plot on the left shows the amount of time my system exported energy. The plot on the right,
shows the amount of time the system imported energy. Time is in seconds.

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