A $$3$$ phase, $$3$$ stack, variable reluctance stepper motor has $$20$$ poles on each rotor and stator stack. The step angle of this stepper motor is

The dc motor, which can provide zero speed regulation at full load without any controller is

In a transformer, zero voltage regulation at full load is

A single-phase $$50$$ $$kVA,$$ $$250$$ $$V/500V$$ two winding transformer has an efficiency of $$95\% $$ at full load, unity power factor. If it is reconfigured as a $$500V/750V$$ auto-transformer, its efficiency at its new rated load at unity power factor will be