ABB RELION REB670, Applications Manual

Page: 80 / 554

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
4.2.2.5 Example on how to connect a wye connected three-phase CT set to the
IED
SEMOD55055-352 v11
Figure 21 gives an example about the wiring of a wye connected two-phase CT set to
the IED. It gives 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.
Section 4
1MRK 505 370-UUS A
Analog inputs
74 Busbar protection REB670 2.2 ANSI
Application manual