Power failure detecting for sensing drop=out of AC mains voltage - using digital evaluation of frequency of mains voltage by passing through frequency multiplier, rectifier and monostable flip=flop to controller.

摘要

The failure of the a.c. voltage is detected by digital evaluation of the frequency of the mains voltage. The a.c. voltage (U) is converted into half-waves and fed to a retriggerable monoflop circuit (18) whose time constant is slightly greater than the period of the a.c. mains voltage. The a.c. voltage is transformed or potential divided to match it to the circuit (14) for detection of the voltage failure. The frequency of the mains voltage can be increased and the monoflop's time constant corresp. reduced. USE/ADVANTAGE - Simple and reliable long-term detection of a.c voltage failure.