h) Each generator arranged for parallel operation shall be provided with reverse-power protection with a time delay between 3 s and 10 s, tripping the generator circuit breaker at:— maximum 15% of the rated power for generators driven by piston engines— maximum 6% of the rated power for generators driven by turbines.The release power shall not depart from the setpoint by more than 50% at voltage variations down to 60% of the rated voltage, and on AC installations at any power factor variation.i) Generator circuit breakers shall be tripped at under-voltage. This under-voltage protection shall trip the breaker when the generator voltage drops within the range 70% to 35% of its rated voltage.j) The under-voltage protection shall have a time delay allowing for correct operation of the short circuit protection (I.e. longer time delay than the short circuit protection.)k) The under-voltage protection shall allow the breaker to be closed when the voltage and frequency are 85% to 110% of the nominal value.The arrangement of overcurrent- and reverse power relays shall be such that it is possible to reconnect the circuit breaker within 30 s after a release, provided the reason for the activation of the relay not is malfunction of the generator or its driver.l) The arrangement of overcurrent- and reverse power relays shall be such that it is possible to reconnect the circuit breaker within 30 s after a release, provided the reason for the activation of the relay not is malfunction of the generator or its driver.m) See Sec.5 A301 for requirements for temperature detectors in windings.n) For emergency generators special requirements apply. See C302.
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