An electrical system for connecting rotary electric machines (111, 113) with gas turbine spools, further comprising: a first rotary electric machine mechanically coupled with a first gas turbine spool and a second rotary electric machine mechanically coupled with a second gas turbine spool, each said electric machine (111, 113) having an identical even number N ≥ 4 of phases, each phase having a respective index n = (1,...,N), and each phase comprising an identical number P ≥ 1 of coils wound in a configuration in which adjacent phases are radially separated by 2π/NP mechanical radians; a first set of N bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc), each bidirectional converter circuit having an ac side and a dc side, each converter circuit of the first set having a respective index n and being connected at its ac side with the P coils in the nth phase of the first rotary electric machine; a second set of N bidirectional converter circuits for conversion of ac to and from dc, each bidirectional converter circuit having an ac side and a dc side, each converter circuit of the second set having a respective index n and being connected at its ac side with the P coils in the nth phase of the second rotary electric machine; an R-channel electrical network; and a switching arrangement having a number R of dc outputs for connection with the R-channel electrical network, wherein 1 ≤ R ≤ N/2 and each dc output has respective index r = (1,...,R), and wherein, for all n, the switching arrangement connects the dc side of the nth converter circuit in said first set with a dc side of the nth converter circuit in said second set to facilitate dc power transfer between the first gas turbine spool and the second gas turbine spool via the switching arrangement. a first rotary electric machine mechanically coupled with a first gas turbine spool and a second rotary electric machine mechanically coupled with a second gas turbine spool, each said electric machine (111, 113) having an identical even number N ≥ 4 of phases, each phase having a respective index n = (1,...,N), and each phase comprising an identical number P ≥ 1 of coils wound in a configuration in which adjacent phases are radially separated by 2π/NP mechanical radians; a first set of N bidirectional converter circuits for conversion of alternating current (ac) to and from direct current (dc), each bidirectional converter circuit having an ac side and a dc side, each converter circuit of the first set having a respective index n and being connected at its ac side with the P coils in the nth phase of the first rotary electric machine; a second set of N bidirectional converter circuits for conversion of ac to and from dc, each bidirectional converter circuit having an ac side and a dc side, each converter circuit of the second set having a respective index n and being connected at its ac side with the P coils in the nth phase of the second rotary electric machine; an R-channel electrical network; and a switching arrangement having a number R of dc outputs for connection with the R-channel electrical network, wherein 1 ≤ R ≤ N/2 and each dc output has respective index r = (1,...,R), and wherein, for all n, the switching arrangement connects the dc side of the nth converter circuit in said first set with a dc side of the nth converter circuit in said second set to facilitate dc power transfer between the first gas turbine spool and the second gas turbine spool via the switching arrangement.