Interference suppression circuit for no=voltage circuit breaker - evaluates supply control signal only during zero transition of supply voltage and stores control value in memory

摘要

An integrated circuit is used for the control of electrical power to a load using a pulsed full-wave control of a triac. A binary control signal is derived by a zero cross-over switch and this is compared with a reference to generate a regulating output that is particularly sensitive to noise. The problem is overcome by entering the signal into a memory (SZ1) when the zero cross-over is detected. The memory signal is received by a second stage (SZ2) controlled by detection of the negative half-wave. This produces the firing pulses for the triac stage. ADVANTAGE - Signal processing occurs at non-critical point to avoid transient effects.