At present, the power supply required for general household appliances is 220V/50Hz, but some users'power supply can not be stabilized at 220V, especially in rural areas. Voltage is sometimes unstable (easy to damage household appliances). Under normal conditions, household appliances with voltage between 190 and 245V can start, but if the voltage fluctuation range is large, it is bound to start. Influencing the performance of electrical appliances, generally speaking, the greater the fluctuation range, the greater the impact on electrical appliances. If the fluctuation range of voltage does not exceed 220 V up and down 20V, no voltage regulator is needed. But if the fluctuation of voltage is large, such as over 20V, it is better to have a voltage regulator, especially when the voltage is below 200 V, it must be equipped with a voltage regulator. Of course, this refers to electricity. Voltage is often on the low side or on the high side, but only occasionally, it does not necessarily have to be equipped with a voltage regulator.