User Manual

Accessories
14.2 Accessories for 3UG4 monitoring relays
3UG4 / 3RR2 monitoring relays
326 Manual, 02/2013, NEB927043002000/RS-AA/002
Transformer connection
Transformer connecting cables must be twisted and not routed in parallel to live cables to
protect from emitted interference. Keep the length of the connecting cables to a minimum.
The resistance at the transformer connecting cable must not exceed 5 Ω to ensure correct
fault current monitoring. This is ensured by the following limits given here as examples.
Conductor cross-section [mm²] AWG/[kcmil] Max. cable length [m]
0.5 20 70
1.0 18 140
1.5 16 210
2.5 14 / 12 300
4.0 10 550
Note
We recommend using twisted cables.
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① Maximum cable lengths (see table above) ① Length ≥ 10 m (shielded, twisted, grounded cables)
Note
Use shielded, twisted, and grounded cables for transformer connecting cables with a length
of more than 10 m.