SBW series three phase full automatic compensated power voltage stabilizer applicant to when the power network fluctuates or the load current varies, it can keep output voltage in steady state automatically, compared with other voltage stabilizers, it has the advantage of large capacity, high efficiency, no wave distortion, stable voltage adjustment, suitability for kinds of loads,bearing instantaneous overload, working continually for long time, as well as free transferring between manual control and automatic control etc., besides, it is provided with protection against over-voltage, over current, phase failure/ phase sequence, delay and error protection etc, and has following merits: small volume, light weight, convenient installation and relit is reliable running and so on.