SUPPLY SYSTEM OF LINE CURRENT

摘要

PURPOSE:To minimize the loss of electric power within a line current supply circuit and at the same time facilitate an easy formation of an IC, by controlling the voltage to be supplied to the line in accordance with the circuit resistance for a circuit current supply circuit that supplies the line current to the terminal unit via a line. CONSTITUTION:The voltage detecting circuit DETv is provided to the line current supply circuit LCF to detect the voltage VL between the lines L1 and L2. At the same time, the current detecting circuit DET1 is provided to detect the line current IL. The detection output of circuit voltage is applied to the arithmetic circuit CAL. The circuit VAL performs a calculation of IL=(E-VL)/RS, where RS is the internal resistance of the circuit LCF that is decided previously according to the interline voltage VL and E is the power supply voltage of the circuit LCF. Thus the current ILC to be supplied is decided and then supplied to the comparator COMP. Then the power supply converting circuit CONV is controlled by the output of the COMP.