Tap changer for an asymmetrical phase shifting transfomer

A make before break asymmetrical tap changer for a 10 kVA three phase two core phase shifting transformer with tap changing capability was created for lab use. The tap changer limits circulating current to below 15 A when changing tap positions, has a minimum contact force of 4 psi while changing taps in 0.5 seconds, and has a 10 degree phase shift in one degree increments. The transformer consists of two cores; an excitation core and a series core and will be used as a teaching tool and research instrument in a model power system lab.