| 摘要 |
<p>PURPOSE:To protect a hydraulic turbine by operating a protecting device when a speed of the hydraulic turbine exceeds a determined value for not less than a specified time period and by detecting a unconstrained speed driving state without any operation of the protecting device caused by a transient overspeed. CONSTITUTION:In cases where a speed caused by cutting out a load exceeds an operating value V4 and an overspeed detection relay 1 operates, a set time T5 of an integration type timer is determined to an appropriate value exceeding T0 (an operation time of an overspeed detection relay during a no load operation). In cases where the following equation: TS<=T1+T2+... wherein T1 indicates an operation time of an overspeed detection relay during a unconstrained driving is satisfied, when TS exceeds T1, not to mention when TS is below T1, the speed is judged to be at a level not occuring during a normal drive. As the result, a hydraulic turbine 6 can be protected by operating a protecting device 5 according to the directions of a protecting device 2 to close an inlet valve.</p> |
