these conditions is primarily a function of I
2
R copper losses. Because temperature
increases with current, it is logical to apply overcurrent elements with inverse time-
current characteristics. The generator overcurrent applications are complicated by the
complexity of generator thermal characteristics and the time-varying nature of current
experienced during starting and when the generator drives a time-varying load.
The generator rotor overload function GRPTTR protects rotor windings against
excessive temperature rise as result of overcurrents.
9.16.3 Setting guideline
Two setting examples will be given for two applications as shown in Figure
204.
100MVA
380/18kV
YNd5
G
100MVA
18kV
3210A
500kVA
18/0,4kV
Dy5
100/1
1000/5
Field rating:
810A, 260V DC
320MVA
242/11kV
YNd5
G
315MVA
11kV
16533A
1400kVA
11/0,55kV
Yd11
100/5
1500/5
Field rating:
1520A, 295V DC
a)
b)
IEC12000182-1-en.vsd
IEC12000182 V1 EN
Figure 204: Two application examples
First example (shown in a) is for a 100MVA machine and the second example (shown
in b) is for a 315MVA machine.
It is important to know which CT (that is, on HV or LV side of the excitation
transformer) is used. Make sure that appropriate CT ratio (for example, 100/1 or
1000/5) is set on these three analogue inputs.
All settings will be given in a table format for both applications.
1MRK 502 071-UEN - Section 9
Current protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 401
Application manual
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