Delta CT2000 Series, User Manual, Page: 625 / 634

Chapter 19 EMC Standard Installation Guide

CT2000 Series
19-12
Criteria for earthing system and EMC
TN-S TN-C TT IT
Safety of
Personnel
Good
Continuity of the
PE conductor
must be
ensured
throughout the
installation
Good
Continuity of the
PE conductor
must be ensured
throughout the
installation
Good
RCD is
mandatory
Good
Continuity of the
PE conductor
must be
ensured
throughout the
installation
Safety of
property
Poor
High fault
current (around
1kA)
Poor
High fault
current (around
1kA)
Good
Medium fault
current (< a few
dozen amperes)
Good
Low current at
the first fault (<
a few dozen
mA) but high
current at the
second fault
Availability of
energy
Good Good Good Excellent
EMC behavior
Excellent
Few
equipotential
Problems:
- Need to handle
the high
leaking
currents
problem of the
device
- High fault
current
(transient
disturbances)
Poor
(prohibited)
- Neutral and PE
are the same
- Circulation of
disturbance
currents in
exposed
conductive
parts (high
magnetic-field
radiation)
- High fault
currents
(transient
disturbances)
Good
- Over-voltage
risk
- Equipotential
Problems:
- Need to handle
the high
leaking
currents
problem of the
device
- RCD
(Residual-
current device)
Poor
(should be
avoided)
- Over-voltage
risk
- Common–
mode filters
and surge
arrestors must
handle the
phase to phase
voltage.
- RCDs subject
to nuisance
tripping when
common-mode
capacitors are
present
- Equivalent to
TN system for
second fault