Siemens SIRIUS 3UG4 Equipment Manual page 255

4. Route the transformer connecting cables at a greater distance to live cables
5. a) Using solid shield sleeves or wound shield sleeves made of soft iron sheet metal may be
advisable to be able to monitor for small fault currents at extremely high rated currents.
We recommend using a soft iron sheet metal shield with a thickness of 0.1 mm at minimum
and fold it around the cable bundle several times so that the overall shield is 1 mm at
minimum. The shielding sleeve length (L) must correspond to the internal diameter of the
transformer used.
b) A solid shield sleeve, e.g. turned from a normal, low-carbon tool steel must be precisely in
contact with the internal ring of the residual current transformer. The wall thickness of the
sleeve must be 1 mm at minimum, the length of the sleeve (L) must correspond to the
internal diameter of the transformer used.
SIRIUS 3UG4 / 3RR2 monitoring relay
Equipment Manual, 07/2021, NEB927043002000/RS-AD/005
①
Phase (and neutral conductor)
②
Shield sleeve
③
Residual current transformer
13.2 Accessories for 3UG4 monitoring relays
Accessories
255