Author Topic: Calibration  (Read 1876 times)

robiles

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Calibration
« on: March 31, 2016, 10:49:08 PM »
Hi!
How often does calibration needs to be done?
We are in a condo and we only get 2 line from the main CB, we have 230V line to line. I've connected two CT to each line and and connected them to MTU slot A and C. The black and white wire of the MTU also to each of the line. We've established communication with the ECC but the voltage and kW reading seem to be twice the expected value. Is it correct that I have 0.5 as calibration for the kW and Voltage or is there something else I must do? MTU has blinking green and fixed red. Checked voltage using a volt meter and the kW by counting how much appliances and watt rating of each I'm using.

Also, I've connected a similar to measure my solar output. The problem is the same, twice reading for kW (haven't checked voltage) as compared to what my inverter tells me. Also it doesn't read as negative even after flipping the CT orientation and the CT A and C slot. So I applied calibration of -0.5.

Am I doing this correctly or fooling myself?

Thanks

pfletch101

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Re: Calibration
« Reply #1 on: April 01, 2016, 10:43:27 PM »
Hi!
How often does calibration needs to be done?
We are in a condo and we only get 2 line from the main CB, we have 230V line to line. I've connected two CT to each line and and connected them to MTU slot A and C. The black and white wire of the MTU also to each of the line. We've established communication with the ECC but the voltage and kW reading seem to be twice the expected value. Is it correct that I have 0.5 as calibration for the kW and Voltage or is there something else I must do? MTU has blinking green and fixed red. Checked voltage using a volt meter and the kW by counting how much appliances and watt rating of each I'm using.

Also, I've connected a similar to measure my solar output. The problem is the same, twice reading for kW (haven't checked voltage) as compared to what my inverter tells me. Also it doesn't read as negative even after flipping the CT orientation and the CT A and C slot. So I applied calibration of -0.5.

Am I doing this correctly or fooling myself?

Thanks

If you mean what I think you mean when you write: "The black and white wire of the MTU also to each of the line.", i.e. that you connected the black wire to one line and the white to the other, that is where your problem is! The black wire should be connected to one live line, but the white wire should be connected to neutral - the same bus bar that the return wires of your household circuits are connected to. Wiring the MTU's white wire to the opposite live lead will, indeed, double your voltage and power readings.
« Last Edit: April 01, 2016, 10:55:55 PM by pfletch101 »
Peter R. Fletcher
TED Pro Home - main MTUs monitoring utility and PV Solar feeds; 2 Spyders monitoring selected individual circuits