An automotive rotary electrical apparatus with less than four switching
control elements capable of blocking a field current while preventing
breakage of the switching control elements in response to a malfunction
in a feeder circuit for a field coil is proposed. First and second
switching control elements controlled by first and second control
signals, and first and second diode elements are used. The field control
circuit switches the first control signal to the on-level signal while
keeping the second control signal as the on-level signal, then switches
the second control signal to the off-level signal while keeping the first
control signal as the on-level signal, and further switches the first
control signal to the off-level signal while keeping the second control
signal to the off-level signal, when a short-to-power malfunction of the
positive terminal or a short-circuit malfunction of the first switching
control element occurs in the feeder circuit for the field coil.