| 摘要 |
The system is used for collective protection of several apartments with a common entrance in a residential building with shared tap water or central heating pipelines. The system is both effective and reliable. The security system includes the following assemblies: door bell transformer (6),between the two terminals of the secondary winding (5) of which are connected as many subsystems (1), (2), (3) and (4) as there are apartments to be protected in the common entrance of the residential building. Each subsystem (1), (2), (3), and (4) contains switched in series bell (8 and 13), a mode switch (9 and 14), a switch (7 and 12), and a sensor (10 and 15). The terminals of switches (9 and 14) for each subsystem (1), (2), (3), and (4) are connected to the building tap water or central heating pipeline.<IMAGE>
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