PROGRAMMABLE SAFETY ELECTRIC SOCKET CONTROLLER AND METHOD OF SUPPLYING POWER TO LOAD CONNECTED WITH SAFETY ELECTRIC SOCKET

摘要

PURPOSE: To reduce the possibility of electrification, by a method wherein it is identified whether an actual load is connected to a safe electric socket or a false load seems to be connected to the safe electric socket by the erroneous contact of a human being at a safe voltage value. CONSTITUTION: If an output voltage Vw is symmetrical, an output voltage waveform is checked and, if it is a sine wave, it is checked whether or not a load impedance Z is smaller than the minimum value Zh of a human impedance. If the measured value of the impedance is not smaller than Zh, the phase deviation between the phases of a load voltage and current is measured and, if 045, an internal parameter P is set to be positive and an excitation pulse is applied. After that, a switch S1 is closed for a half cycle of the parameter P and a residual voltage Vrp is measured at the end of the half cycle of the parameter P. If two residual voltage values Vrp corresponding to the positive and negative parts of a system voltage are obtained, the switch S1 is opened and the difference between the two residual voltage value Vrp is compared with a threshold value Vrh. If the difference is larger than the threshold value Vrh, it means that a connected load is a human load.