| 摘要 |
<p>PURPOSE:To obtain a contact abnormality detector to improve safety by detecting a deposition condition with a timer means for a prescribed time even when the turn-on condition of a relay contact is continued for a long time. CONSTITUTION:When a temperature near a heater is much lower than the set temperature at a heater conducting initial time, a timer means counts over for a prescribed time and a relay-off signal is outputted from a relay comparing control means 11 at this moment. The deposition detecting checking is continued for a prescribed time. At this time, when the detecting signal of a relay switching detecting means 10 and the output signal of the relay comparing control means 11 are different, the relay comparing control means 11 judges that the deposition of a relay contact 4a is obtained, and a temperature fuse deposition signal is outputted. A safety circuit control means 14 to receive this outputs an 'H' pulse and interrupts the conducting to the heater 5. Thus, the danger such as a double trouble can be minimized.</p> |
