Grounding
Ground Connections in TT, TN and IT Alternating Current Systems Distribution systems Ground connections in our alternating current systems (single-phase, three-phase, rotary current systems), these systems can be put into three separate categories (IEC 60364): System name
Type of ground connection to the energy source (first character)
Type of ground connection to the electric operation (second character)
TN system
A certain point on the neutral conductor, normally close to the feeding current source, is grounded directly.
The body of the electrical equipment is connected with the ground point using a ground conductor. Depending on the application of the N conductor, TN systems are split into three different types: S: Separated neutral and equipment grounding conductors C: Combined neutral and equipment grounding conductors (PEN) C-S: System with TN-C section(s) and TN-S section(s)
Variations TN-S system TN-C system TN-C-S system
TT system
A certain point on the neutral conductor, normally close to the feeding current source, is connected with a ground connection.
The body of the electrical equipment is connected with other grounding elements, independent of the neutral ground.
IT system
No point in the system is grounded directly.
The body of the electrical equipment is grounded.
NOTE: Security stipulations for these various systems (cut-off conditions for example) are found in IEC 60364-4-41.
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33002439 10/2019
