How to properly connect MEW-01?

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klew
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Joined: Thu Jun 27, 2019 12:16 pm
Location: Wrocław

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There are three main mistakes that installers make.

1. The first is the installation of current transformers in reverse polarity. In this case, the active power will have negative values. Of course, this refers to situations when we are not returning energy to the grid from the PV system, because then it is natural that the active power will be negative. If we have a PV system, it is best to verify the direction of the current transformers at night.

2. The second mistake is installing current transformers on the wrong phases. The sequence of phases for current transformers (I1, I2, I3) must match the sequence of voltage phases (V1, V2, V3). It is easy to confuse the wires, so it is best to use a multimeter to check the correctness of the installation. We set the multimeter to AC 400 V. Then we connect the first probe to V1 and the second to the wire on which the I1 transformer is installed. If the multimeter shows 0 V, it means that the transformer is in the correct place. If it shows 400 V, it means that the transformer is on the wrong phase. We repeat the measurement for V2 and I2, as well as V3 and I3. Of course, all installation and measurement work should be performed by a person with the appropriate qualifications (high voltage).

3. The third mistake is placing more than one wire in a current transformer. The transformer can be installed on a single wire. It cannot be installed on a multi-wire cable.
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efisupla
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Joined: Mon Jan 15, 2024 2:20 pm

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Hello,

I have 3 phase and 1 is showing reverse power. Everything seems to be hooked up correctly. Can you help me get this fixed?
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klew
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Location: Wrocław

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efisupla wrote: Mon Jan 15, 2024 2:22 pm Hello,

I have 3 phase and 1 is showing reverse power. Everything seems to be hooked up correctly. Can you help me get this fixed?
If only active power is with invalid sign (and corresponding energy registers), then you can try to flip current transformer on that phase.
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