Emax Low voltage air circuit-breakers - ABB Download Center

Switching and protection of generatorsReverse power protection RPThe reverse power protection is tripped when active power isincoming to the generator rather than outgoing as it is undernormal conditions. Power reversal takes place if the mechanicalpower supplied by the main motor driving the generatordrops sharply. In this condition, the generator acts as a motor,and can cause serious damage to the prime movers, such asoverheating in steam turbines, cavitation in hydraulic turbines,or explosions of uncombusted diesel fuel in diesel engines.Outgoing Active PowerCondition OKPR123 trip unit not trippedDieselEngineGenPR123Incoming Active PowerCondition not OKPR123 trip unit tripped1SDC200207F0001When the power measured by the trip unit falls below zero, thePR123 trip unit trips, opening the circuit-breaker and therebypreventing any damage.66/34ABB SACE