ABB Relion 670 Series Applications Manual page 412

Section 15
Logic
Example for use of GRP_OFF signal in FXDSIGN
The Restricted earth fault function REFPDIF (87N) can be used both for auto-transformers and
normal transformers.
When used for auto-transformers, information from both windings parts, together with the
neutral point current, needs to be available to the function. This means that three inputs are
needed.
ANSI11000083 V1 EN-US
Figure 197: REFPDIF (87N) function inputs for autotransformer application
For normal transformers only one winding and the neutral point is available. This means that only
two inputs are used. Since all group connections are mandatory to be connected, the third input
needs to be connected to something, which is the GRP_OFF signal in FXDSIGN function block.
FXDSIGN
GRP_OFF
ANSI11000084 V1 EN-US
Figure 198: REFPDIF (87N) function inputs for normal transformer application
406
REFPDIF (87N)
I3PW1CT1
I3PW2CT1
I3P
ANSI11000083_1_en.vsd
REFPDIF (87N)
I3PW1CT1
I3PW2CT1
I3P
ANSI11000084_1_en.vsd
1MRK 511 358-UUS A
Application manual