For 3-wire, three-phase systems with 2 CTs, its required to 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, it is possible to know the actual current value of N phases.

Please refer the below wiring diagrams