Patent ID: 7369391

Claim:
A drive circuit of a direct-current voltage-driven magnetic contactor including an operating coil that is capable of direct-current excitation, a main contact that is in an open circuit condition in an attracting period of an initial period of excitation by the operating coil and is in a closed circuit condition in a holding period, the holding period being subsequent to the attracting period, and an auxiliary contact that carries out an opening and closing operation that is reverse with respect to the main contact, and wherein a first end of the operating coil is connected to a positive electrode side of an exciting direct-current power supply and a second end of the operating coil is connected to a first end of the auxiliary contact, the drive circuit comprising: a starting semiconductor switching element provided between a second end of the auxiliary contact and a negative electrode side of the exciting direct-current power supply; a direct-current power supply voltage detecting circuit that outputs a start instruction signal when an applied voltage of the exciting direct-current power supply exceeds a predetermined value; a driving direct-current power supply whose negative electrode side is connected to the negative electrode side of the exciting direct-current power supply; a first drive circuit that makes the starting semiconductor switching element perform an ON operation upon receiving the start instruction signal, using the driving direct-current power supply as an operating power supply; a charging capacitor whose one end is connected to a positive electrode side of the driving direct-current power supply via a diode, and whose other end is connected to the second end of the auxiliary contact; a current limiting semiconductor switching element connected in parallel to the auxiliary contact; and a second drive circuit that makes the current limiting semiconductor switching element perform a switching operation when a terminal voltage of the charging capacitor reaches the predetermined value.