... , voltage modulator, controller, starter switch for automobile, air circuit breaker, heavy –load relay, magnetic starter, vibrator rectifier, etc ... 3. AgZnO Usage: Mainly used in circuit breakers, especially in universal circuit breakers. Other fields of application are ... circuit breaker.9. AgWC/AgWCC Usage: Mainly used in heavy –duty switching devices, such as MCCB, ACB, residual current circuit ...