| 摘要 |
1281121 Ionisation detectors SIEMENS AG 7 Jan 1970 [8 Jan 1969] 762/70 Heading G1N In a fire-detecting system, a fire-door is automatically closed upon detection of a fire. As shown, a reference ionisation chamber K1 and a smoke detection ionisation chamber K2 are provided in the door control circuit which is connected to the mains via a transformer KT. Upon detection of smoke the potential at point 1 changes thus blocking a F. E. T. T1 which then causes a relay A to be denergized, via T2. Contact a then de-energized a door-holding, solenoid for closing the fire-door. In a modification, the transformer KT may be replaced by the doorholding solenoid which is provided with a secondary winding. A switch PT is provided for testing purposes. The system includes at least one fire alarm circuit which is operated undependently of the control circuit. |
