发明授权
- 专利标题: Thermal protection apparatus for a synchronous machine
- 专利标题(中): 同步电机热保护装置
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申请号: US815678申请日: 1991-12-31
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公开(公告)号: US5305234A公开(公告)日: 1994-04-19
- 发明人: David R. Markus , Kenneth M. Eichler , Donald S. Kimmel , Gerhard K. Kasprowicz , Robert S. Murray
- 申请人: David R. Markus , Kenneth M. Eichler , Donald S. Kimmel , Gerhard K. Kasprowicz , Robert S. Murray
- 申请人地址: PA Pittsburgh
- 专利权人: Westinghouse Electric Corp.
- 当前专利权人: Westinghouse Electric Corp.
- 当前专利权人地址: PA Pittsburgh
- 主分类号: H02H6/00
- IPC分类号: H02H6/00 ; H02H7/06
摘要:
A synchronous machine is protected from closely spaced instances of excessive field current and an excessive volts/hertz ratio by a control system which models rotor and stator cooling to provide memory of recent periods of excessive heating. Maximum excitation limiting and volts/hertz ratio limiting modules in a microprocessor based automatic voltage regulator for the machine generate time delayed limit signals which override voltage feedback control when the respective parameters exceed threshold values. The limiters each increment a count when the associated threshold value is exceeded and generate the associated limit signal when a predetermined count is reached. The predetermined counts and the counting rates are selected such that the delay intervals are inversely proportional to the amount by which the threshold values are exceeded. The counts are decremented at a rate which models rotor and stator cooling when the respective parameters return below the threshold values. If another event occurs before the count reaches zero, the delay before limiting action is reinitiated is shortened by an amount related to the residual heating.