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GENERAL INSTRUCTIONS FOR CTC
UNDER POLE COMPACT
TRANSFORMER SUBSTATION
IG-086-GB
version 02
11.07.2007
3.6. PROTECTION AND EARTHING CIRCUIT
The
CTC
TS is provided with an internal earthing circuit to connect the different elements to
the external earthing circuit.
Inside the enclosure, there are two earth disconnection boxes corresponding to:
•
Protection earthing circuit (metallic parts).
•
Service earthing circuit (transformer zero-sequence earth).
3.6.1. Protection Earth Connection
The protection earthing circuit (metallic parts) provided with the
CTC
Compact Transformer
Substation is connected to the protection earthing disconnection box on the right-hand side
wall of the transformer area, looking from the LVB.
The metal enclosure is connected to the protection earthing circuit (metallic parts) which is
finally connected to the protection disconnection box.
3.6.2. Service Earth Connection
The service earthing circuit (zero-sequence earth) connects the LVB zero-sequence to its
disconnection box located in the LVB area, on the left-hand side wall, looking from the LVB.
It is recommended to make the connection with insulated copper wire.
Both earthing circuits are independent.
The Transformer Substation project must include the section regarding the execution of the
earth connection (check the Utility's standard project), as well as the justification of its sizing.
The Earthing Installations section of the Regulations regarding Power Plants, Substations
and Transformer Substations (MIE-RAT 13) describes the requirements this kind of facility
must comply with.
VERY IMPORTANT
:
The LVB zero-sequence bar (service earth connection) is not connected to the
protection earth connection bar (metallic parts).
