ABB REG670 - Simplified Logic Diagram

7.8.9.4 Simplified logic diagram
Uinj
Rshunt
ROTIPHIZ
REX060
REG670
1
I
U
u_i_ref
u_u_ref
X
S
K1
K2
Compare &
Evaluate
ZRef1
ZRef2
3
2
4
56
7
IEC10000327-2-en.vsd
Bare
Z
Measured
Z
Inj
I
Inj
U
¸
R
f
IEC10000327 V1 EN
Figure 129: Simplified logic diagram for sensitive rotor earth fault protection,
injection based ROTIPHIZ
1
The sensitive rotor earth fault protection function receives amplified injected voltage and
current via the REX060 unit as two voltages signals. (Voltage inputs in the IED)
2 The phasor of injected voltage U
Inj
and phasor of injected current I
Inj
is calculated by using
special filter from raw samples. Observe that phasors are calculated for the injected
frequency.
3
The complex bare impedance is calculated from U
inj
/ I
inj
.
4, 5 The complex measured impedance is derived as Z
Measured
= Z
bare
* k1 + k2 [Ω].
6 The fault resistance (R
f
) is calculated from the complex measured impedance and a selected
complex reference.
7 Selection of one (out of maximum 2) Z
Ref
.
Section 7 1MRK502052-UEN B
Impedance protection
290
Technical manual