Generally speaking, the voltage of refrigerator should be 220 V, but it is common that the voltage can't keep on 220V all the time, especially in those rural areas. Under normal circumstances, the refrigerator can work on within 187 ~ 242 V voltage. However, the performance of refrigerator will be impacted if the voltage fluctuation is too big. In general, the larger the range, the greater the refrigerator will be impacted. If the voltage is lower than 187 V, the refrigerator can’t work on and even burn down the compressor. If the voltage is higher than 242 V, the compressor and other electric parts are easy to be burnt out.
Moreover, if the voltage fluctuation range is less than 10 V, a regulator is not necessary. But if the voltage fluctuation is big, such as more than 20 V, installing a regulator is very necessary. Especially for those areas where the voltage is always less than 200V or higher than 230V. On this condition, we should match a regulator(AVR). Of course, this means the voltage is often low or high. If only individually comes, it is not necessary to match a regulator.
A regulator of above 750 W will be suitable for most of the refrigerators.