Microcomputer controlled electric contactor with power loss memory

摘要

The coil of an electromagnetic contactor is controlled by a microcomputer which stores control data in an internal RAM memory. An integrated circuit chip provides a tightly regulated +5 volt supply voltage to the microcomputer and generates reset signals on power up and power loss. A logic circuit distinguishes a power loss reset from a power up reset and transfers the microcomputer to a STOP mode in which only the RAM is energized to retain the control data. Reserve power to energize the RAM during a power loss of up to several minutes in duration is provided by a large capacitor which is kept charged by the regulated +5 volt supply. Voltage on the capacitor is checked through the integrated circuit on power up to determine if sufficient voltage was maintained to assure the integrity of the RAM.