Autotransformer Winding, Solidly Earthed - ABB RELION 650 Series Applications Manual

1MRK 505 363-UEN A
REFPDIF
IdN/I
REFPDIF
IdN/I
IEC09000110-4-EN V2 EN-US
Figure 28: Connection of the low impedance Restricted earth-fault function REFPDIF for
6.1.2.3

Autotransformer winding, solidly earthed

Autotransformers can be protected with the low impedance restricted earth-fault protection
function REFPDIF. The complete transformer will then be protected including the HV side, the
neutral connection and the LV side. The connection of REFPDIF for this application is shown in
figure 29.
Application manual
- 1
I3PW1CT1
I3P
- 2
I3PW2CT1
I3P
a zig-zag earthing transformer
Earthing
transformer
Section 6
Differential protection
Protected
winding W1
Protected
winding W2
IEC09000110-4-EN.vsd
M13048-13 v9
69