Hi all,
I got bit on a quoted job the other day.
I installed an additional power meter on an existing 3 phase CT circuit that feeds a power factor controller.
The burden of the new instrument was checked against the existing CT's and power factor controller. The accuracy class of the system was maintained to under 0.5%.
What caught me out was that the new power meters CT connection terminals were internally common on the outgoing side.
In analog input card terms, I was hoping the meter would be 'differential' but it turned out to be 'single ended'.
I had to do a bunch of rewiring to get it all to work. Naturally, one side of the CT's were commoned together and grounded.
The question: Is it common for one side of a power meters terminals to be common? There was no mention of this in the manufacturers data sheet. The instrument in question was an ABB M2M Power analyser.
Picture attached for clarity.
I got bit on a quoted job the other day.
I installed an additional power meter on an existing 3 phase CT circuit that feeds a power factor controller.
The burden of the new instrument was checked against the existing CT's and power factor controller. The accuracy class of the system was maintained to under 0.5%.
What caught me out was that the new power meters CT connection terminals were internally common on the outgoing side.
In analog input card terms, I was hoping the meter would be 'differential' but it turned out to be 'single ended'.
I had to do a bunch of rewiring to get it all to work. Naturally, one side of the CT's were commoned together and grounded.
The question: Is it common for one side of a power meters terminals to be common? There was no mention of this in the manufacturers data sheet. The instrument in question was an ABB M2M Power analyser.
Picture attached for clarity.
