![background image](http://html.mh-extra.com/html/abb/relion-670-series-reg670/relion-670-series-reg670_applications-manual_4795160.webp)
1. The ratio for delta connected CTs shall be set √(3)=1.732 times smaller than the
actual individual phase CT ratio.
2. The power transformer phase-shift shall typically be set as Yy0 because the
compensation for power transformer the actual phase shift is provided by the
external delta CT connection.
3. The zero sequence current is eliminated by the main CT delta connections. Thus
on sides where CTs are connected in delta the zero sequence current elimination
shall be set to Off in the IED.
The following table summarizes the most commonly used wye-delta phase-shift
around the world and provides information about the required type of main CT delta
connection on the wye side of the protected transformer.
IEC vector group
ANSI designation
Positive sequence no-load
voltage phasor diagram
Required delta CT connection
type on wye side of the
protected power transformer
and internal vector group
setting in the IED
YNd1
YD
AC
Y
IEC06000559 V1 EN-US
DAC/Yy0
Dyn1
D
AB
Y
Y
IEC06000560 V1 EN-US
DAB/Yy0
YNd11
YD
AB
Y
IEC06000561 V1 EN-US
DAB/Yy0
Table continues on next page
Section 7
1MRK 502 071-UUS A
Differential protection
154
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual
Summary of Contents for RELION 670 SERIES REG670
Page 1: ...RELION 670 SERIES Generator protection REG670 Version 2 2 ANSI Application manual ...
Page 2: ......
Page 44: ...38 ...
Page 66: ...60 ...
Page 102: ...96 ...
Page 200: ...194 ...
Page 442: ...436 ...
Page 486: ...480 ...
Page 508: ...502 ...
Page 514: ...508 ...
Page 524: ...518 ...
Page 658: ...652 ...
Page 736: ...730 ...
Page 774: ...768 ...
Page 828: ...822 ...
Page 829: ...823 ...