| 摘要 |
PURPOSE:To enable the operation of a generator up to the extent of its allowable limit by changing the set point in proportion to the gas compression of the inner- cooling gas of the generator and also by generating an alarm output after a fixed time limit when an actual field current exceeds the allowable value. CONSTITUTION:An input signal 1a, giving a ''0'' indication when the inner-cooling gas compression of the generator is at the rated one and its negative value increases in proportion to the drop of gas compression, and an input signal 3, giving a ''0'' indication when a field current is ''0'' and a negative value increases in proportion to the increase of current, are input to a comparator 14. When the cooling gas compression is at the rated one and the field current becomes equivalent to the set point of a setting device 10, the output of the comparator is inverted to positive, and in the case where the condition is maintained in excess of the set time limit of a timer 15, a transistor is in continuity, a relay 17 functions, and an alarm signal is issued. When the input 1a drops due to the drop of the cooling gas compression, an alarm signal is issued earlier by the time length which proportionates to the field current corresponding to the dropped current. Thus the generator can be used up to the extent of an allowable limit and also the device is utilized as an overexcitation time control device. |
