ABB REG670 Applications Manual page 310

Section 8
Impedance protection
304
C
stat
IEC11000011 V2 EN
Figure 162: Injection via open delta VT connection
It must be observed that the resistor R
damping. The resistance R
current as it has high resistance. This injection principle can be used for applications
with various generator system earthing methods. It is therefore recommended to make
the injection via the open delta VT on the terminal side in most applications.
Accuracy for STTIPHIZ is installation dependent and it mainly depends on the
characteristic of grounding or voltage transformer used to inject signal into the stator.
Note that large variation of the ambient temperature and variation of stator
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
U
1
Y
Y
Y
R
d
∑
U
<
√
R R

N d √
3

R
N
IEC11000011-2-en.vsdx
is normally applied for ferro-resonance
d
is will have very little contribution to the earth fault
d
1MRK 502 071-UEN -
/ U
2
I
inj
a
+
U
inj
-
b
2
⌡
1

U

2
Application manual