Transformer Turn Ratio Tester|XHBB128B Product Overview The XHBB128B Transformer Turn Ratio Tester replaces traditional single-phase bridge methods with a precision three-phase inverter power supply, delivering faster, more accurate, and more comprehensive transformer ratio analysis. Unlike conventional testers that rely on mains power and measure phase-by-phase, the XHBB128B generates its own clean three-phase test voltage—eliminating harmonic interference and enabling