ABB RELION 670 Series Technical Manual page 407

1MRK 502 066-UUS B
The protection principle is based on injection of voltage to the exciter point of the field circuit.
7
REG670
ANSI11000014 V1 EN-US
Figure 214: Example installation for rotor injection
1 Generator unit consisting of a synchronous generator and a step-up transformer
2 Generator field winding
3 Capacitor coupling unit which is used to provide insulation barrier between rotor circuit and injection
equipment
4 Cable used to inject the square-wave signal into the rotor circuit
5 Connection for measurement of injected current. This signal is amplified in REX060 before it is passed on to
IED for evaluation.
6 Connection for measurement of injected voltage. This signal is amplified in REX060 before it is passed on to
IED for evaluation.
7 Two VT inputs into IED which are used to measure injected current and voltage
8 Protection for excessive over-voltages posed by generator. REX060 can withstand without damage
maximum voltage of 120V and when used together with REX062 up to 240V.
The injection signals are generated in a separate unit, REX060. The signals have square wave form
and are injected to the generator via the coupling capacitor unit REX061 to the excitation circuit.
In the REX060 unit the injection voltage and current signals are amplified to a level that is
compatible with the analogue voltage inputs of IED. In the IED the measured signals are evaluated
to detect rotor ground faults.
Technical manual
8
U>
V inj
Rshunt
I
V
REX060/ RIM module
Generator Protection Panel
4
3
R C
5
REX061
6
ANSI11000014_1_en.vsd
Section 7
Impedance protection
GUID-21C6C7C9-6D62-43C2-BD49-D7E71415D95F v2
Step -up
Transformer
1
GEN
2
R
N
401