Gossen Metrawatt M817S Mains-analysis device, Mains analyser M817S Hoja De Datos

E-17

APPENDIX E/ Common Circuit Connections

When connecting to CTs, the X1 terminal is normally connected to the H1 terminal of 

the device for correct reference phasing.

Where power measurements or voltage/current phase relationships are not important, 

the X1 and X2 terminals may be connected in series with the output device in any line 

(hot or return) or in any relationship of X1/X2.

ISO boxes can be used in a number of ways. These methods include: 

• connecting them to the secondary of CTs for metering by the Energy Platform.

• inserting them in series with the load current to measure low current values.

• connecting them to a non-Dranetz clamp-on current transformer and using that CT 

to monitor current with the Energy Platform.

The figure on the next page shows an ISO box connected from any current channel 

input to a permanently installed CT. The connection shown is made in the load return 

line for current monitoring only. Polarities of the ISO box and CT are kept in-phase by 

matching markings of X1 to H1. Scale factors of both devices must be multiplied 

together to get the resultant scale factor. The scale factor value calculated for a CT is 

3.375.