| 摘要 |
<p>PURPOSE:To increase the safety for a temperature controller, by controlling an electric power control element with the zero volt of an AC power supply and at the same time checking a temperature detecting electrode wire that constitutes a temperature sensor. CONSTITUTION:An output Zp of a zero-cross pulse generating part C is applied to the base of a transistor TR20 of a disconnection detecting circuit B. Thus the current (io) of a constant current source 22 is partially by-passed to a temperature detecting electrode wire 9, and the collector voltage VKO of an output TR27 of the circuit B is turned into the zero-cross pulse voltage to be supplied to a temperature control part D. The part D delivers not only the signal of a temperature detecting circuit A but a gate trigger signal VG of an electric power control element 7. Accordingly the zero-cross pulse is discontinued to the optional disconnection of the wire 9 as well as to the disconnection of connectors P1 and P2 in order to detect the state of disconnection.</p> |
