Australian Installation - selecting correct VT model, and calibration?


I have purchased one of the IotaWatt Aussie Bundles.

From that page, I also purchased the recommended 9V reference transformer model “AC910”, from the store RadioParts.

(By the way - the URL on the Iotawatt page is actually broken - the correct URL for the AC910 is here)

One thing is - that adapter has reversible pins (i.e. can be centre-positive or centre-negative). The IotaWatt documentation didn’t mention which configuration to use - I went with centre-positive, as that’s more common. However, to a newbie like me, it’s unclear if this is actually correct, or if anything bad might happen if you get it wrong - does it make sense to mention it in the docs?

Secondly, I have configured my IotaWatt to connect to my wifi network, and am following the setup guide in the documentation. I am up to the part about Voltage Transformer Configuration.

My unit has the following default configuration:

If I click on the “0”, to bring up the setup page, these are the models I can pick from:

My AC910 also has the model “M9233”, and “DS-12-09” printed on the power brick.

However, I just wanted to confirm which model I should be selecting - is it the “DCSS AC910(AUS)”?

(I did see this older post from 3 years ago, which mentions using generic240V, with some values they determined - not sure if that’s still up to date).

And if that is the correct model, do I need to click the “Calibrate” button?

I was not aware of this development. Apparently DOSS has changed their supplier for the AC910. When I look at the DOSS website I see a picture that matches this newer model being sold by Radio Parts. It is clearly different than the model that I have tested and provided voltage and phase-shift calibration for.

I will remove that transformer from the website reference. If someone would send me a sample of the newer model, I will test and calibrate a table entry for the new model and restore the reference in the website.

I am confused by this. The picture on the Radio Parts website doesn’t appear to have any way to do that. Moreover, AC does not have polarity in the negative/positive sense. It’s true that the output can be in phase or 180° contra-phase to line, but that isn’t really an issue that cannot be resolved in many other ways.

As above, there is no table entry that corresponds to this new transformer.

My advice for now would be to select the old AC910 and definitely calibrate the voltage. If you have a reliable meter to calibrate, I would be interested to know how far off it is with the AC910 configuration, and what value the calibration procedure reveals as more accurate.

The phase-shift will still be unknown, and so It would be best if I can get a sample to measure.

Hi Bob,

Hmm, I can order a second unit and ship it to you as a sample, if that would help? Did you want the JayCar one you recommend on the website as well?

I’ll need to buy it locally, and ship myself, as I don’t think RadioParts ships to the US. Let me do that.

Did you end up receiving the AZ CT’s?


I have a JayCar, thanks. Radio Parts is not very accommodating, considering I’ve probably sent them 100 orders. It would be very helpful to your mates if I coould get that source back in the tables.

Yesterday. Tiny little things.

The 9V reference voltage transformer needs to be AC ( ie no polarity). Use the Jaycar one that Bob has already set the calibration in the OS.

From my experience, it does need to wired the “right way around” so that it is in the same phase as the output of the CT’s

How I discovered this was that I needed to hit the “reverse” switch on all my CT’s to get a sensible reading.
I thought that was odd, because I was very careful and double checked the fitment of the CT’s.
I did read (on this forum) someone mentioned the “polarity” of the VT, so I swapped mine over, redid my CT setup up and Perfect !

Unlike the US and EU plugs, yours cannot be reversed in the socket, but just like the CTs, you can check reverse for the VT. Easy as that.

@overeasy I ordered one more of the RadioParts adapters, and I’ve shipped it to your US address. Hopefully you’ll receive it soon! =)

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Finally on the receiving end of the Aus-US shipping experience. Thanks, I’m confident this resource will prove to be as useful as it’s predecessor once measured and cataloged.