T3-6CTA CT inputs range

What range to choose for CT inputs of T3-6CTA? Now there are ‘Out of range’ value. And values about 1.x without any CT connected.
Firmware is T3_6cta_REV2_26.hex

First set them to volts and see what you get please and report back.



Dear Maurice,

If you mean Signal type - it’s unavailable, you can see it on my picture. If you mean Range - 0-10V there didn’t change anything.

Hi Philip_Lykov
Please set the range to 0–100A . I see we have a bug in the latest firmware, we’ll fix it and release a firmware update in a day or two. You can update the firmware using T3000 -> help -> check for updates.


Hi Philip_Lykov:
You can update using T3000 -> help -> check for updates->Download Firmware And Updtade now .

Dear Spring,

Updated. Now I see the same wrong values but with ‘Amps’ as units. Please check the screenshot at first post: there are some random values even with shorted inputs.

After connection of CTs I see on all inputs the same value of 99.90 Amps.

Dear Spring and Maurice,

I really need your assistance on this topic since after changing the T3-6CT from old to new one it doesn’t work in production system.

Spring is mentioning something about the CT type, can you confirm that you are using the 330mv AC output type please.

The old T3-6CTis able to read 0–5VAC from current sensor, this new one support output 0–333mv type current sensor that is always easy to get on the market .

I use 50A 0-300mVAC clamping current sensors bought from you in 2015 year.

OK, good news for that. I trust you have updated the firmware and the T3000 front end recently.

We haven’t been able to duplicate any issues in the office. It will help if you could show a photo of your test setup and also a screen shot from T3000 if you could please.


Spring will have a look at this thread and experiment some more. So far we havent been able to duplicate this. We may have to get the unit back and on the bench.

One question: Could you put a volt meter on AC range across the output of the CT and tell me what reading you get there. Hopefully its less than 300mv AV.

So actually I find 0.9-8 VAC on CT inputs of T3-6CT.
It’s strange since they mentioned in your invoice as “Clamping current transformer, fixed 50A AC input,
0-300mVAC out”. With old T3-6CT they didn’t work well also.
Ok, I will order a few new on Ali now. Sorry.

I am not clear which CT’s you’re referring to. We sell some 330mvac type and also some 0-5V DC transducer type CT’s. There’s also some 5Amp output type which are for the large electrical metering equipment found in the electrical trade. I dont know of any of our sensors which can output up around 8VAC.

It seems they are broken.

Hi Philip
please update your T3-6CT to the latest firmware by ISP tool .
Firmware download link : https://www.temcocontrols.com/ftp/file/T3_6cta_TYPE4_REV2.6.zip

Dear Spring,

Could you please post here change log for this version?

When you do the firmware update you will see a list of the recent changes. You do have a chance to stop the update before actually going ahead if you see something in the changelog
that you’re not comfortable with.