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Series 700/200 Power Meters (PM7/PM2) VS. PM800 (PM8) CT wiring for system type 30 w/ 2CTs

Background Information
Some customers that are familiar with CT wiring for the PM800 do not know there is a wiring difference for the PM200/PM700 for Three-Phase 3-wire Power Systems when using 2 CTs.


For 3-wire, three-phase systems with 2 CTs, connect terminal S2 = X2 of CT1 to the I2+ terminal of the PM200/PM700 instead of the I1- (on the PM800). The PM200/700’s firmware use the inverse of the residual current that goes into the I1-, I2- and I3- to know the actual value of current for the third phase. This is not a calculation. It is rather an actual value. By using N-1 CTs in power systems, you can know the actual current value of N phases.

Left: PM200/700 CT Wiring Right: PM800 CT Wiring

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