#Diesel generator startup time full#
Phase angle differences as little as 12 degrees can develop shaft torques as high as 150% of full load and damage shaft couplings and other turbine and generator components. When synchronizing a generator to the system, the synchroscope should be rotating less than one revolution every 20 seconds Phase angle differences should be minimized and no more than 5 degrees out of phase when the circuit breaker contacts close. Typically, turbo-generators are designed to withstand a full load field with no load on the machine for only 12 seconds after that, severe damage can occur to the stator core iron laminations. If a rapid abnormal increase occurs in field current, terminal voltage, or both, immediately open the field breaker and inspect the related equipment for proper working condition before reestablishing a field.ĭuring off-line conditions, at no time should the field current be greater than 105% of that normally required to obtain rated terminal voltage at rated speed in an unloaded condition. Should either or both shafts come to a stop, the field current should immediately be removed to prevent overheating damage to the collector or slip rings.Īfter the field breaker is closed, the generator field indications should be closely monitored. On cross-compound units where a field is applied at low speeds or while on turning gear, extreme caution must be exercised. In addition to monitoring the various generator support systems for cooling and lubrication, electrical parameters, temperatures, and vibration, inattention to the following areas has caused problems in the past:Īt no time should excitation interlocks or protective relay functions be bypassed or disabled for the purpose of energizing a generator’s direct current (DC) field winding.įor generators requiring field pre-warming, the manufacturer instructions and established procedures should be followed relative to the allowable field currents.Ī generator field should not be applied or maintained at turbine speeds above or below that recommended by the manufacturer.
Operating conditions ( startup and shutdown) that have forced units off-line or have damaged or shortened the life of turbine (or generator) components in the past are highlighted in the guideline to prevent recurrences in the future.
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