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2 Installation
2.9
Earth cable connections
To avoid currents through MV cable shields, earth conductors must pass inside both phase CT and
earth CT before connecting them to equipotential earth node.
See fig.1 or fig.2
Sono altresì da evitare i collegamenti mostrati di seguito:
WARNING: connection as in fig.3 or fig.4 can cause unexpected earth fault protection trips
(function 50N or 51N or 67N).
WARNING: while passing the conductors through the CT earth, pay attention to the direc-
tion, in order to avoid connection like in fig.5 and fig.6.
WARNING: it’s recommended that MT shields earth connection are made of isolated conduc-
tor, in order to avoid any contact with metallic parts on the ground before passing through
the earth CT and phases CT.
WARNING: in case of installation with directional earth fault protection (function 67N) pay
attention to the direction of CT earth installation: current must pass always from P1 to P2.
Summary of Contents for QMT Series
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Page 2: ...2 IT UK ITALIANO 3 ENGLISH 45 QMT ...
Page 15: ...Quadri Media Tensione QMT Manuale installatore 15 Tipo 2 Tipo 3 Tipo 4 ...
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Page 57: ...Medium voltage switchgear QMT 57 Installation manual Type 2 Type 3 Type 4 ...
Page 86: ...86 Notes ...
Page 87: ...87 ...