This produces a waveform of one polarity operating at a frequency twice that of the mains supply.

经过整流后得到的是一个频率为交流电源两倍的单极波形。

youdao

Heat meters designed to operate from an ac mains supply shall be wired in accordance with wiring regulations applicable.

温度传感器由AC交流电源供应，配备的电线符合电线规章。

youdao

Numerous types of inverter are available, but not all are suitable for use when feeding power back into the UK mains supply.

许多类型的变换器是通用的，但不是所有的适合使用，当能连回到英国的供应。

youdao

The NEA wants government help to get more communities connected to the mains supply to cut fuel poverty.

BBC: Rural struggle without mains gas

We have had no mains supply for over 48 hours.

BBC: Water chaos affects thousands in Northern Ireland

In the 70s when I was away from a mains electricity supply, a 12-volt battery would keep my respirator operating for just 20 minutes.

CNN: 'I lived in an iron lung for seven years'