The TN-C-S earthing type has four letters and the fourth letter, just like the third letter, indicates how the neutral and PE conductors are utilized.

S is defined by “Separated” which means that the neutral and PE conductors are separated and independent from each other.

C is defined by “Combined” which means that the neutral and PE conductors are combined into one conductor (PEN conductor) that acts as the current return conductor during both steady state and fault conditions.

The third letter indicate how the neutral and PE conductors are utilized.

This gives a TN system, which is how the load chassis is connected to earth using either a neutral or a protective earthing (PE) conductor.

N is defined by “Neutral” which defines the load chassis as connected to neutral.

T is defined by “Terre”, which gives a TT system, which is the how the load chassis is grounded to earth using an earthing electrode.

Specification for Power System Analysis.Cloud - Collaborative Project Management - NetPM.Leverage Analytics with a Unified Digital Platform Microgrid Controller & Energy Management - µGrid.Electrical SCADA & Control System - eSCADA.Relay Protection & Asset Management - eProtect.Digital Substation & Automation System - SAS.Advanced Distribution Management System - ADMS.

Automated Protection & Coordination - Star.

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