An electrical system for connecting rotary electric machines 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 (401-404) 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 (111-1) and a second three-phase sub-machine (111-2); the second rotary electric machine is a dual wound rotary electric machine comprising a third three phase sub-machine (113-1) and a fourth three-phase sub-machine (113-2); the set of bidirectional converter circuits (401-404) 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 (401-404) 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 (111-1) and a second three-phase sub-machine (111-2); the second rotary electric machine is a dual wound rotary electric machine comprising a third three phase sub-machine (113-1) and a fourth three-phase sub-machine (113-2); the set of bidirectional converter circuits (401-404) 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 (111-1) and a second three-phase sub-machine (111-2); the second rotary electric machine is a dual wound rotary electric machine comprising a third three phase sub-machine (113-1) and a fourth three-phase sub-machine (113-2); the set of bidirectional converter circuits (401-404) 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 . <EOS>