Specifications

18
Schneider Electric
Review (continued)
TN-S system
IT system
An initial insulation fault can lead to a phase-to-phase voltage between a phase
conductor and the equipment ground.
This is unacceptable for electronic devices supplied directly by a phase-to-neutral
connection and which cannot withstand the phase-to-phase voltage.
Example: Withstand of RFI filters of (large) variable speed drives.
This is the best system from an EMC
viewpoint:
b Low risk of ground loop (radiated fields).
b The neutral current is not carried by the
protective conductor (conducted
disturbances).
Care must taken to ensure equipotentiality
E52283E52284
Shielding connected
at both ends
PE
Shielding connected
at both ends
Loop capable
of capturing
radiated fields
Z
Cabling Guidelines