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Functions
Ue Connected to
Neutral
Transformer
Ue Connected to
Broken Delta
Winding
Not Connected;
Calculation of U
0
Ue Connected to
any VT
Ue Connected to
Rotor
190
1. Ue connected to neutral transformer: Connection of the U
voltage transformer in the machine starpoint
2. Ue connected to broken delta winding: Connection of the U
the broken delta winding
3. Not connected: Calculation of the displacement voltage by means of the three
phase-earth-voltages, if the U
4. Ue connected to any VT: measuring of any other voltage; the function 100–
%–stator earth fault protection is blocked.
5. Ue connected to Rotor: measuring of any other voltage; the function 100–
%–stator earth fault protection is blocked.
6. Ue connected to loading Resistor: The UE-input is used by the 100–
%–stator earth fault protection with 20–Hz–injection. The function 100–%–stator
earth fault protection with 3rd harmonics is blocked.
As an earth fault in the starpoint causes a reduction of the measured 3rd harmonic
compared with the faulty case, the protective function is implemented as undervoltage
stage (5202 U0 3.HARM<). This arrangement is the preferred application.
If no neutral transformer exists, the protective function is based on the zero
component of the 3rd harmonic of the terminal voltages. This voltage increases in
case of a fault. In this case, the protective function is an overvoltage stage (5203 U0
3.HARM>).
Like for the connection to the broken delta winding, an increase of the 3rd harmonic in
case of a fault also results for the calculated voltage. The 5203 U0 3.HARM>
parameter is also relevant for this application.
With these connection types the function 100–%–stator earth fault protection is
blocked.
Figure 2-91 illustrates the logic diagram of the 100– %–stator earth fault protection.
input is not connected
E
input to the
E
input to
E
7UM62 Manual
C53000-G1176-C149-3
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