Groups of camshafts are connected to camshaft adjusters via adapters. A contact 41, an overcurrent detector section 43, and a zero phase current transformer 44 are disposed in order from a power supply side to a load side, and a lightning arrester 3 is connected between the overcurrent detector section 43 and the zero phase current transformer 44. A poppet valve assembly is provided for insertion in an opening in the opened food container and biased to enable it to accommodate opened food containers of varying sizes.