{"id":4389,"date":"2025-02-24T16:53:02","date_gmt":"2025-02-24T11:23:02","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=4389"},"modified":"2025-07-16T13:31:45","modified_gmt":"2025-07-16T08:01:45","slug":"critical-clearing-angle-critical-clearing-time","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ee\/power-generation-concepts\/critical-clearing-angle-critical-clearing-time","title":{"rendered":"Concept of Critical Clearing Angle and Critical Clearing Time"},"content":{"rendered":"

Let the system of figure shown above be operating with mechanical input Pm at a steady angle of \u03b40(Pm = Pe) as shown by the point a on the Pe \u2013 \u03b4 curve of figure shown below. When a three-phase fault occurs at the point P of the outgoing radial line, the electrical output of the generator instantly reduces to zero (Pe = 0) and the state point changes to b. The accelerating area A1 begins to increase and so does the rotor angle while the state moves along bc. At time tc corresponding to the rotor angle \u03b4c, the fault line is cleared by the opening of the line circuit breaker. The system now becomes healthy and transmits power Pe = Pmax\u22c5sin \u03b4, i.e., the state point shifts to d on the original Pe \u2013 \u03b4 curve. The rotor now decelerate and the decelerating area A2 begins while the state point moves along de.<\/p>\n

\"Generator\"<\/p>\n

\"Fault\"<\/p>\n

In above figure, \u03b4cr is called \u201ccritical clearing angle\u201d and the time corresponding to it is called \u201ccritical clearing time\u201d, tcr .<\/p>\n

\"Clearing<\/p>\n

Note:<\/strong><\/p>\n