Example On How To Connect A Star Connected Three-Phase Ct Set To The Ied - ABB RELION 650 Series Applications Manual

1MRK 504 158-UEN A
Where:
a)
b) and
c)
It shall be noted that depending on national standard and utility practices, the rated secondary
current of a CT has typically one of the following values:
• 1A
• 5A
However in some cases the following rated secondary currents are used as well:
• 2A
• 10A
The IED fully supports all of these rated secondary values.
4.2.2.5 Example on how to connect a star connected three-phase CT set to the
IED
Figure 9
It gives also an overview of the actions which are needed to make this measurement available
to the built-in protection and control functions within the IED as well.
Application manual
is symbol and terminal marking used in this document. Terminals marked with a square
indicates the primary and secondary winding terminals with the same (that is, positive)
polarity
are equivalent symbols and terminal marking used by IEC (ANSI) standard for CTs. Note
that for these two cases the CT polarity marking is correct!
It is recommended to:
• use 1A rated CT input into the IED in order to connect CTs with 1A and 2A
secondary rating
• use 5A rated CT input into the IED in order to connect CTs with 5A and 10A
secondary rating
gives an example about the wiring of a star connected three-phase CT set to the IED.
For correct terminal designations, see the connection diagrams valid for the
delivered IED.
Section 4
Analog inputs
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