| 摘要 |
<p>A time delay switch capable of connecting a consuming device to a power source via a first current path for a predetermined time and including a first normally open circuit breaker connected in the first current path. A second current part is provided including the first normally open circuit breaker and an auxiliary normally closed circuit breaker connected in series with a thermal element made of a memory alloy characterized by a two-way temperature sensitive shape changing characteristic and a resistive heater electrically connected in series with the thermal element and thermally coupled thereto. A push-button activator is provided which upon actuation thereof closes the contact of the first circuit breaker resulting in current flowing in the first and second current paths, thereby producing heating of the thermal element and a corresponding shape change therein. After a predetermined time the shape change of the thermal element acts on the auxiliary circuit breaker and opens the contacts thereof, thereby ending the heating of the thermal element which then cools down and returns to its initial shape, which results in opening of the normally open first circuit breaker, whereby the flowing of the current to the consuming device ceases.</p> |
