Author Topic: Solar Generation Sensing Using 20A CTs  (Read 846 times)

chabotd

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Solar Generation Sensing Using 20A CTs
« on: January 14, 2018, 04:53:17 PM »
I have a second MTU monitoring grid-tied solar generation. The PV system backfeeds the main breaker panel with a 35A 2-pole breaker.  I am using two 20A CTs, one on each leg of the 35A breaker. Will this work correctly or must I use the 200A CTs?

If the 20A CTs will work, do I have to do any calibration?

pfletch101

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Re: Solar Generation Sensing Using 20A CTs
« Reply #1 on: January 15, 2018, 05:18:16 PM »
AFAIK, the 20A CTs are only compatible with the Spyder device's inputs, unless you have 'special' 20A MTU CTs, which I am not aware of as being available. Unless one of the TED folks wanders by and gives a definitive answer, you may want to raise a ticket on the main site (http://www.theenergydetective.com/ticket) to ask this question.
Peter R. Fletcher
TED Pro Home - main MTUs monitoring utility and PV Solar feeds; 2 Spyders monitoring selected individual circuits

Joacchim

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Re: Solar Generation Sensing Using 20A CTs
« Reply #2 on: March 29, 2018, 06:18:11 PM »
Most PV strings (the ones I have, anyway) are designed for max 20A double pole breakers. If your PV input never exceeds 20 amps I don't see why using 20A CT's wouldn't work. - FWIW

pfletch101

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Re: Solar Generation Sensing Using 20A CTs
« Reply #3 on: March 30, 2018, 12:35:57 PM »
Most PV strings (the ones I have, anyway) are designed for max 20A double pole breakers. If your PV input never exceeds 20 amps I don't see why using 20A CT's wouldn't work. - FWIW

The issue is not whether the current exceeds the rating of the CT, but whether there are 20A CTs that are compatible with the TED MTUs (as opposed to the Spyder unit). Plugging a 20A CT intended for use on a Spyder into a MTU CT input is (at the very least) likely to result in calibration problems.
« Last Edit: March 30, 2018, 05:08:07 PM by pfletch101 »
Peter R. Fletcher
TED Pro Home - main MTUs monitoring utility and PV Solar feeds; 2 Spyders monitoring selected individual circuits