ZERO CROSS RELAY ACTUATION METHOD AND SYSTEM IMPLEMENTING SAME

摘要

Disclosed is an electromechanical relay drive system which prolongs relay li fe by ensuring operation of the relay in a manner to make and break contact betwee n the contact electrodes at a zero crossing point of the switched waveform. Relay aging an d environmental variations are dynamically compensated upon each actuation of the electromechanical relay to ensure proper timing of the energization and de-energization of the relay to ensure switching at the zero crossing point. Additionally, the drive system described compensates for variations in the actual contact operation during actuation for the positive and negative half cycle of the switched waveform. Furthermore, the system of the instant invention alternately energizes and de-energizes the electromechanical relay during the positive a nd negative half cycles of the switched waveform to prevent metal deposition from one contact electrode to the other. This system calculates the appropriate delays on a dynamic historical perspective by sensing slope changes of the coil voltage and current.