降低电压需求的电量超过发出的电量或配给的电量时为了减小功耗电力公司通常将降低交流电源配给的电压
When the electricity required to reduce voltage exceeds the electricity generated or allocated, power companies usually lower the voltage allocated to the AC power supply in order to reduce power consumption
以上为机器翻译结果，长、整句建议使用 人工翻译 。