ABB REG670 - Page 315

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C
stat
R
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U
inj
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inj
R
d
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d
R
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IEC11000011-3-en.vsd
Y
Y
IEC11000011 V1 EN
Figure 139: Injection via open delta VT connection
It must be observed that the resistor R
d
is normally applied for ferro-resonance
damping. The resistance R
d
is will have very little contribution to the earth fault
current as it has high resistance. This injection principle can be used for applications
1MRK502052-UEN B Section 7
Impedance protection
309
Technical manual