Record current for industrial application - CO2 reduction

I just purchased my unit and I am anxiously waiting for its arrival. I am looking to use this for an industrial application where I am measuring current on possibly 6 different circuits that are heating for an industrial application. I am working with companies and we are going to test a new energy-efficient heater and see the results and try and get the energy rebates from the local utility company. We are going to be testing before and after the new units. The reduction in energy usage will relate to the reduction of CO2 emissions from our factory usage.
My question is regarding voltages, the data stored, and how to export for analysis. Some machines we test will have heaters that be 230 volts, some 460. I don’t believe it will matter as long as I am just looking at the current reading before and after and the unit is powered by 110 volt plug, is that correct? Second, what data is stored in the database, and third is there an easy export to CVS to analyze the data. What I would be looking at is about two hours of data running with the old heaters and then the next day switch to new heaters and running about 2 hours and comparing the current used in that time period compared to the old heater current usage. … Thanks for your help.

The unit is powered by a 5VDC USB supply. It doesn’t matter where you get that, but you will need to have an AC reference transformer in order to measure anything, including Amps. The AC signal is the heartbeat of IoTaWatt and it is used to synchronize to individual AC cycles while measuring. As long as all of those voltages are derived from the same primary AC source, you should be able to get an accurate measurement of Amps, but nothing else.

I’m assuming you have a three-phase 277V/480V industrial supply with some transformers to produce 120V/240V and 230V/400V, so all of the various supplies are at the exact same frequency. If any of the voltages are derived from a different source like a generator of VFD inverter, it will not work.

The IoTaWatt records Watts and VA at 5 second intervals. Your VA will of course be incorrect, but the voltage is also recorded and so VA / V = A and you can extract Amps.

Graph+ will allow you to plot Amps over any period and will also integrate the result in the statistics section to show Ah for the selected period. You can also extract amps using the Query API. You can get the average amps used over the period and use that to calculate Ah.

Just a note to say that the Amps readings are really useful from an energy perspective only if there is no reactive power - i.e. unity power factor. That said, I don’t understand how two heaters operating at unity power factor can produce a different amount of energy/Amp since Wh, Calories, BTUs and Joules are the same as VAh at unity PF.

Thank you for the reply.

Yes, I would agree that the AC signal should be from the same source. Both come into the building.
One will be from the 120-volt outlet as the primary power and sensor for the unit. The other source is 480 for the machine and a transformer internally in the machine to provide 230 to the heaters.
The Graph+ might be nice but I would want to select the data from only when we used the testing.

Can I use the Query API to export the data in the 5 second increments to use with our energy company to show the energy savings? It looked like it averages it out.

For your side note, the two different heaters being evaluated are standard resistive heaters using conductive heat transfer on a steel tube (barrel) with no insulation. The other is using a radiant heating element with ceramic fiber insulation. The combination gives you a 30-50% reduction in energy required to maintain the temperature inside the tube.

Another note:
At the customer, we can not usually connect to their wifi. Can I create an access point on my phone and then have it and my computer access both? Do I need it connected to wifi to record the data (I don’t believe so). So for example, if I bring it to my customer, wire it up, start a test, and record the start time. The next day start the test and recorded the start time. I can then come into the office later and analyze all the data without connecting it to wifi at my customer, correct?

You can easily do that with Graph+. It uses query aso it’s the same data, just a higher level interface to extract the data. Graph+ can export the data in CSV format. But if you prefer to roll your own with query, that’s fine.

Yes, you can query the five second increments. Each 5 second increment is a time-weighted average of the samples taken during that increment.

Yes, you can usually connect to a phone access point. You do not need to be connected to WiFi to record the data, although you will not be able to tell if it is working properly without WiFi beyond observing a red glow on the LED.


OK, I have just completed the energy study for my first customers. I want to make sure I have this correct. The unit measures the VA, and it uses the reference voltage of the 9V AC REF to get the power voltage. If I take the VA reading and then divide it by the voltage reading, I get the amperage, correct?.
I am currently using one sensor on each leg of a 3-phase 460-volt system to measure the amperage and the energy savings using the new heater bands. I can compare, and I see before and after, and I see the total current is 35% less than before. I am trying to get the actual current to see the value of the energy saved.
To make it more difficult I set up the input with the double box checked so I don’t want to change anything so the before and after settings were the same.
How would I determine the actual current in each leg with this setup?


Create an output with units Amps.

In some buildings, where waste heat can be reduced, you might also be able to estimate a not-insignificant reduction in energy required for air conditioning.

For “scientific” or “billing” purposes, do some due diligence calibration, especially if you’re using 3rd-party CTs. I ordered some “blue brand” ones from Amazon, and those readings were off by 30-40% - did not expect that at all.
Use an ammeter or put the new CTs in series with a known-good one and make the corresponding tweaks on the Inputs page, with a Model:generic CT, if necessary.

No doubt a reference to YHDC SCT series CTs. If you saw that much discrepancy, against a reliable standard, no doubt they were not the SCT013-000 100A:50mA model and probably one of the voltage output models which are not supported. They have a model SCT013-xxx where xxx is the maximum rated current at which the CT puts out 1V. They will not work properly as IoTaWatt requires current transformers.

Additionally, there are counterfeit YHDC SCT013 CTs that look at first glance just like SCT013-000 but are reportedly very inaccurate. If you look close the brand is YHDO rather than YHDC.

Bona-fide SCT013-000 CTs are supported and work pretty well with accuracy in the 1% range.

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