① The input voltage range can be made wider (because of the long stroke of the carbon brush).
② The output voltage waveform is the same as the input voltage waveform, and the phase is also the same.
③ High efficiency of the whole machine (the loss of auto-voltage regulator is small, and the general efficiency of AC small voltage regulator is more than 95%).
④ Good adaptability of load properties.
⑤ The small AC voltage stabilizer is easy to manufacture, low cost and low price.
⑥ It can be made into a high-power compensation power supply.
