Abstract: A capacitor 1 which is provided so as to be installable in a first loading part C of a first electrical power device and a second loading part S103 of a second electrical power device S is configured to have an external shape such that a first abutment part which, upon loading of the capacitor into the first loading part, comes into abutment with the first loading part C differs from a second abutment part 26 which, upon loading of the capacitor into the second loading part S103, comes into abutment with the second loading part S103.

Abstract: In a ringing signal control circuit for controlling supply of a ringing signal from a ringing signal generator to a subscriber's line in response to a call signal destined thereto, a switching element is repeatedly switched to connect the ringing signal generator to the subscriber's line under control of a switching signal from a switch controller. In order to suppress a surge voltage due to connection and disconnection of the subscriber's line for the ringing signal generator, a memory stores a time data signal representative of a transition time from a reference voltage level to an optimum voltage level for the subscriber's line. The optimum voltage level is the level at which the connection and disconnection can be carried out without generation of the surge voltage. A voltage comparator compares the ringing signal with the reference voltage to produce a coincident signal.