| 摘要 |
<p>The system is designed to actuate a sound or other type of alarm with two independent time delays. The system is supplied from two series contactors which are associated with two relays and two independent electronic circuits. These circuits permit change of state of the contactors with a time delay after connection of the voltage supply. The second contactor (X2) can only change its state after the first contact (X1) has changed state, and applied voltage to its electronic control circuit via a relay. Each contactor after changing state cuts the supply to its own winding and to the electronic circuits which controls it. The two relays ensure the zero reset of the time delay of the electronic circuits.</p> |
