SIPROTEC 4 7SA522 Distance Protection Relay for Transmission ...
SIPROTEC 4 7SA522 Distance Protection Relay for Transmission ...
SIPROTEC 4 7SA522 Distance Protection Relay for Transmission ...
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<strong>SIPROTEC</strong> 4 – <strong>7SA522</strong><br />
<strong>Distance</strong> <strong>Protection</strong> <strong>Relay</strong> <strong>for</strong> <strong>Transmission</strong> Lines<br />
Typical connections<br />
Typical connection of<br />
current and voltage<br />
trans<strong>for</strong>mers<br />
The typical AC connection has<br />
3 phase current trans<strong>for</strong>mers<br />
and 3 phase-ground (earth)<br />
voltage trans<strong>for</strong>mers. The<br />
neutral (residual) current (I N =<br />
3I 0 ) is measured via the I4-<br />
current trans<strong>for</strong>mer as the<br />
sum of the three phase currents.<br />
The zero sequence voltage<br />
3V 0 is not measured externally<br />
but calculated by the<br />
microprocessor.<br />
A (L1)<br />
B (L2)<br />
C (L3)<br />
52<br />
Circuit<br />
breaker<br />
I N<br />
V N<br />
Flush mounting<br />
Q1<br />
Q2<br />
Q3<br />
Q4<br />
Q5<br />
Q6<br />
Q7<br />
Q8<br />
R15<br />
R16<br />
R17<br />
R18<br />
Busbar<br />
I A(L1)<br />
I B(L2)<br />
I C(L3)<br />
V A(L1)<br />
V B(L2)<br />
I 4<br />
V 4<br />
V C(L3)<br />
R13<br />
R14<br />
Line<br />
Figure 26<br />
Voltage trans<strong>for</strong>mer connections:<br />
Separate open<br />
delta trans<strong>for</strong>mer<br />
The three phase-to-ground<br />
(earth) voltage trans<strong>for</strong>mers<br />
are typically connected as illustrated.<br />
The V4 voltage<br />
trans<strong>for</strong>mer measures the<br />
zero sequence voltage 3V 0<br />
(Ven) via a separate VT (open<br />
delta connection). This ensures<br />
an additional voltage supervision.<br />
The V4 trans<strong>for</strong>mer can also<br />
be connected to a separate<br />
voltage trans<strong>for</strong>mer <strong>for</strong> free<br />
assignable voltage measurement<br />
(Vx).<br />
A (L1)<br />
B (L2)<br />
C (L3)<br />
Circuit<br />
breaker<br />
52<br />
R15<br />
R16<br />
R17<br />
R18<br />
R13<br />
R14<br />
V A(L1)<br />
V B(L2)<br />
V C(L3)<br />
V 4<br />
Busbar<br />
Line<br />
Figure 27<br />
18 Siemens SIP 4.2 · 08/99
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