An electrical system for connecting rotary electric machines (111, 113) with gas turbine spools of aircraft, further comprising: a first rotary electric machine mechanically coupled with a first gas turbine spool; a second rotary electric machine mechanically coupled with a second gas turbine spool; and a set of bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc) connected with the first and second electric machines; and characterized in that: the first rotary electric machine is a dual wound rotary electric machine comprising a first three phase sub-machine and a second three-phase sub-machine; the second rotary electric machine is a dual wound rotary electric machine comprising a third three phase sub-machine and a fourth three-phase sub-machine; the set of bidirectional converter circuits is a set of N = 4 bidirectional converter circuits, each of which has an associated index n = (1,...,N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine; and the dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit. a first rotary electric machine mechanically coupled with a first gas turbine spool; a second rotary electric machine mechanically coupled with a second gas turbine spool; and a set of bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc) connected with the first and second electric machines; and characterized in that: the first rotary electric machine is a dual wound rotary electric machine comprising a first three phase sub-machine and a second three-phase sub-machine; the second rotary electric machine is a dual wound rotary electric machine comprising a third three phase sub-machine and a fourth three-phase sub-machine; the set of bidirectional converter circuits is a set of N = 4 bidirectional converter circuits, each of which has an associated index n = (1,...,N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine; and the dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit. the first rotary electric machine is a dual wound rotary electric machine comprising a first three phase sub-machine and a second three-phase sub-machine; the second rotary electric machine is a dual wound rotary electric machine comprising a third three phase sub-machine and a fourth three-phase sub-machine; the set of bidirectional converter circuits is a set of N = 4 bidirectional converter circuits, each of which has an associated index n = (1,...,N), and for all n, the ac side of the nth bidirectional converter circuit is connected with the nth three-phase sub-machine; and the dc side of the first converter circuit is connected with the dc side of the third converter circuit, and the dc side of the second converter circuit is connected with the dc side of the fourth converter circuit.