Patent attributes
An engine system comprises first and second electrical generators coupled to lower and higher pressure (LP, HP) shafts respectively of a gas turbine engine. A controller is arranged to receive a signal corresponding to a total electrical power demand P1 and to output control signals to the electrical generators in response thereto such that the first and second electrical generators output electrical powers (1−y)P1 and yP1 respectively when P1≤Pm1, where 0.5<y≤1 and Pm1 is the maximum electrical output power of the first electrical generator. By satisfying the demand P1 mostly by extraction of electrical power from the first electrical generator when possible, the additional mechanical stress on the gas turbine engine resulting from electrical power extraction is reduced compared to the case where 50% or more of the demand P1 is satisfied by the second electrical generator.
