Application Examples - ABB RELION 650 Series Applications Manual

Section 6
Differential protection
For DAB delta connected main CT ratio shall be set for √3 times smaller in RET 670 then the
actual ratio of individual phase CTs. The "StarPoint" parameter, for this particular connection
shall be set
exactly as shown in figure 28.
For more detailed info regarding CT data settings please refer to the three application
examples presented in section
6.1.3.3

Application Examples

Three application examples will be given here. For each example two differential protection
solutions will be presented:
• First solution will be with all main CTs star connected.
• Second solution will be with delta connected main CT on Y (that is, star) connected sides
of the protected power transformer.
For each differential protection solution the following settings will be given:
1. Input CT channels on the transformer input modules.
2. General settings for the transformer differential protection where specific data about
protected power transformer shall be entered.
Finally the setting for the differential protection characteristic will be given for all presented
applications.
Example 1: Star-delta connected power transformer without on-load tap-changer
Single line diagrams for two possible solutions for such type of power transformer with all
relevant application data are given in figure 29.
72
ToObject . It shall be noted that delta DAB connected main CTs must be connected
"Application Examples".
1MRK 504 158-UEN A
SEMOD167854-5 v2
SEMOD167854-110 v6
Application manual