Zones of Protection • Definition of Protection Zone in Power System • Protection Zone for different power system components • Concept of Overlapping Protection Zones • Examples on Protection Zones of Real Power Systems Definition of Protection Zone in Power System • Protection zone is defined as the part of the power system which is protected by a certain protective system • It is established around each power system equipment • The entire power system is covered with several protection zones, and no part of the system is left unprotected Protection zone Protection Zone for different power system components 1. Generator 2. Transformer 3. Transmission Line 4. Loads or Motors 5. Busbar Concept of Overlapping Protection Zones • Neighboring zones overlap so that no “dead spot” are left in the protected system Dead spot Overlapping zones Example on determining protection zones of simple power system Example on determining protection zones of complete power system ❑ Draw the protective zones for the following power systems ❑ Which breakers should open for faults P1 & P2 ? Example on determining protection zones of complete power system ❑ For fault P1 Breakers B24 , B42 open ❑ For fault P2 Breakers B24 , B21 , B23 open • For the following network , Mention and locate the place of the fault which would result in the following trip cases 1. C.B1 & C.B3 are opened 2. C.B2 is opened 3. C.B5 & C.B7 & C.B8 are opened 4. C.B9 & C.B12 are opened 5. C.B11 & C.B12 & C.B14 are opened 6. C.B15 & C.B17 & C.B18 are opened Protective System ❑ The term Protective System ,or simply 'Protection’ is named according to the principle of operation or abnormal condition. Examples • Over current protection • Earth fault protection • Reverse power protection • Under voltage protection • Under frequency protection Protective Scheme ❑ A protective scheme comprises set of protective systems and the protective scheme is named according to the protected equipment Examples • Transformer protection • Motor protection • Generator protection • Busbar protection
