[logikdia-rueckleistungsschutz, 1, en_GB]
Figure 2-104
Logic diagram of reverse power protection
Setting Notes
General
The application of reverse power protection is only possible in 3-phase protected objects. It can only be
assigned to a side of the main protected object or another measuring location. Furthermore, it is a prerequisite
that the device is connected to a three-phase voltage transformer set.
The reverse power protection is only effective and accessible if address 150 was set to REVERSE POWER =
Enabled during configuration of the protection function (Section 2.1.3 Functional Scope).
Under address 5001 REVERSE POWER the reverse power protection can be switched ON or OFF. The option
Block relay allows to operate the protection but the trip output relay is blocked.
Pickup Value
In case of a reverse power, the turbine set must be disconnected from the system as the turbine operation is
not permissible without a certain minimum steam throughout (cooling effect). In case of a gas turbine set, the
motor load can also become too heavy for the network.
In case of a turbine generator unit the level of the active power input is mainly determined by the friction
losses to be overcome and lies within the following ranges:
Steam turbines:
P
reverse
/S
N
≈ 1 % to 3 %
Gas turbines: P
reverse
/S
N
≈ 3 % to 5 %
Diesel drives: P
reverse
/S
N
> 5 %
It is recommended, however, to measure the reverse power of the turbine generator unit with the protection
yourself during primary test (section "Commissioning", "Verification of the Voltage Connections"). As setting
value, use approx. half the measured motoring power. The feature to correct angle faults of the current and
voltage transformers should be used especially for very large machines with a particularly low motoring
energy (see Sections 2.1.4 Power System Data 1 and 3.3.12 Checking the Voltage Connections and Polarity
Check).
2.12.2
Functions
2.12 Reverse Power Protection
SIPROTEC 4, 7UT6x, Manual 225
C53000-G1176-C230-5, Edition 09.2016
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