GEK-113285A G650 Generator Protection & Control System 5-61
5 SETTINGS 5.4 PROTECTION ELEMENTS
5
5.4.8.3 GENERATOR UNBALANCE (46)
The generator unbalance element protects the machine from rotor damage due to excessive negative sequence current.
Negative sequence current is used as operation element. The element has an inverse time stage (stage 1), typically used
for tripping, and a definite time stage (stage 2) typically used for alarm purposes.
Stage 1 trip time is based on an inverse time curve, defined by the equation:
where I
nom
is the generator rated current and K is the negative-sequence (I2
2
T) capability constant normally provided by
the generator manufacturer.
2
*
2
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
=
IpkpInom
I
K
T
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