| 摘要 |
PURPOSE:To protect users from uneasy feeling by using a system in which a warning means is again actuated in case where the normally closed contact of a vibration fire-extinguisher suffers contact failure. CONSTITUTION:An oscillator 21 operates at all times at a low frequency of about 1Hz, for example. When the output and abnormal signal (a) or the supply of electricity to a power source line A are stopped and signal generated in turning a transistor 12 to OFF and output of the oscillator 21 are put in a differential circuit 15 through an ''and'' gate 20, even when the always closed contact 8 of the vibration fire-extinguishing switch is abnormal and a button switch 6 is pushed to open the contact 5-1 under the condition that no electricity is supplied to the power source line A, the output of an OR gate remains ''Hi''. Therefore, the output of the oscillator 21 passes through the differential circuit 15 and is converted into pulse signal there, a reset coil 5b is again excited, the contact 5-1 is opened, and an alarm lamp 18 is again lit. Thus, users can be protected from uneasy feeling. |
