Domestic power line breaker

摘要

An automatic domestic power line breaker comprising a current-to-voltage converter to which is applied an input signal obtained from the secondary of a differential transformer coupled to the power line. The converter output is coupled through a low pass filter to a rectifier, the output of which is connected to a function generator, which provides an output signal comprising a voltage having a slope proportional to the peak amplitude of the rectifier output signal. The function generator output is applied to a first input of a comparator having a second input to which is applied a d.c. threshold voltage. The comparator output signal is applied through an amplifier to control the state of a set of normally open relay contacts series connected in the power line conductors. A feed-back diode shunts the first input and output of the comparator to lock the relay contacts in the open state if the breaker has controlled opening of the contacts. The circuits of the breaker are energized through a restrike switch which must be activated in order to unlock the relay contacts and allow the contacts to be closed when the cause of the input signal which had resulted in opening of the contacts disappears.