Setting Notes - Siemens Siprotec 7UM611 Manual

2 Functions
Figure 2-25

2.12.2 Setting Notes

General Reverse power protection is only effective and available if this function was set during
protective function configuration (Section 2.2, address 131, REVERSE POWER is set
to Enabled. If the function is not required Disabled is set. The address 3101
REVERSE POWER serves to switch the function ON or OFF or to block only the trip
command (Block relay).
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 throughput
(cooling effect) or, in case of a gas turbine set, the motor load would be too heavy for
the network.
Pickup Values The level of the active power input is determined by the friction losses to be overcome
and is in the following ranges, depending on the individual system:
• Steam turbines: P
• Gas turbines: P
• Diesel drives: P
For the primary test, the reverse power should be measured with the relay. The user
should select a setting of 0.5 times the value of the measured motoring energy. This
value can be found under the percentage operational measured values. The feature
of correcting angle faults of the current and voltage transformers should be used es-
pecially in case of very large machines with a particularly low motoring energy (see
sections 2.3).
86
Logic Diagram of the Reverse Power Protection
≈ 1 % to 3 %
/S
Reverse N
≈ 3 % to 5 %
/S
Reverse N
/S > 5 %
Reverse N
7UM61 Manual
C53000-G1176-C127-3