ABB RET670 Applications Manual page 46

Section 3
IED application
40
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.
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
Example on how to connect a wye connected three-phase CT set to the
IED
Figure 8 gives an example about the wiring of a wye connected three-phase CT set to
the IED. 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.
For correct terminal designations, see the connection diagrams valid for
the delivered IED.
1MRK504116-UUS C
Application manual