The proposed overcurrent protection relay with rotating
magnetic field operates as follows. The single-phase AC
current from the CT secondary winding is fed into the device
through terminals 1 and 2 and creates rotating magnetic field
in the primary winding components of RMFR (3-8 of Figure
1). The rotating magnetic field induces two systems of
symmetrical three-phase voltages into the secondary windings
9-14. These systems are phase shifted with respect to each
other by 30 degrees.