| 摘要 |
<p>PURPOSE:To protect a generator against negative phase at an appropriate level even upon change of operating conditions and to minimize restriction on the operation by calculating rotor temperature of generator, at the time of zero negative phase current, from field current and then modifying set level of negative phase protection. CONSTITUTION:Negative phase current and higher harmonic currents contained in the output current from a generator 2 are detected and then they are synthesized or operated in order to monitor total negative phase current which heats the rotor of the generator. A rotor temperature operating means 11 takes in armature current and field current values of the generator 2 and calculates a rotor temperature when total negative phase current is zero for the values thus taken in. Upon variation of rotor temperature due to variation of the operating conditions of the generator 2, a set value modifying means 13 modifies set levels of trip signal and alarm correspondingly. This protective unit realizes setting of appropriate negative phase protective level corresponding to the margin of rotor temperature provided through variation of the operating conditions of the generator 2.</p> |
