| 摘要 |
<p>TRIAC-PROTECTED OUTPUT CIRCUIT A secondary, protective triac is connected in series with a main load-control triac in an a-c output circuit for a programmable controller. The two triacs are coupled to a pair of digital inputs and when the main triac is conducting the secondary triac is not conducting -- unless the main triac stays "on" after an "off" signal is received, signifying a shorted main triac. If that occurs, a triac-failure fuse is blown and the secondary triac switches to conduct current and complete a virtually short circuit through a main power fuse. The blowing of the triac-failure fuse illuminates a neon bulb to give an indication of a main triac failure, and the blowing of the main power fuse illuminates a corresponding neon bulb to indicate a failure on the module and its disconnection from the load.</p> |
