16
SME70, SME70-C, SME70-M-Manual-04-2020
I N S T A L L A T I O N
RESIDUAL CURRENT SENSOR
The residual current sensort must be crossed in the same direction by all active conductors and
hence, also by the neutral conductor if distributed, with the exception of the ground connection
protective conductor. The drawing below shows cases of assembly of the residual current sensor
on unscreened and screened cables; prior to proceeding with assembly, it is necessary to check
that there are no screen-to-ground connections upstream of the sensor.
In order to ensure a linear response from the sensor, the cables must be positioned in the centre of
it so that the magnetic effect of the three cables is perfectly compensated in the absence of residual
current (Fig.2a).
Hence, the assembly indicated in the following drowing, in which phase L3 causes local magnetic
saturation whereby the vectorial sum of the three currents would be non-null, should be avoided.
The same considerations also apply when the sensor is positioned near bends in the cabling.
It is recommended that the transformer be placed away from bends in the conductors).
Armoring
Load
Load
Source
Source
Insulated cables
Shielded cables
Armoring
L1
L3
L2
L1
L3
L2
