Brownouts are sometimes caused by overloaded circuits and are sometimes caused intentionally by the ac utility company in order to reduce the power drawn by users during peak demand periods ( like during hot summers when everyone is using their air conditioners ) 有時(shí)電路過載會(huì)引起電燈暗淡,有時(shí)供電公司有意這樣做,是為了在用電高峰期內(nèi)降低用戶的用電量(比如在盛夏,每家人家都在使用空調(diào)) 。