wired zone, wired detector and wiring

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vedard
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Joined: Wed Dec 05, 2018 12:27 am

wired zone, wired detector and wiring

Unread post by vedard »

Wired alarm host or hybrid alarm host has wired zones. On the mainboard of the alarm host, we can see the terminals such as Z1, COM, Z2, Z3, Z4.....That is the wired zones.
There are two ways for wiring of wired detector and wired zone. That is N/C, It's short for Normal closed. It means the circuit is normal closed and when alarm triggers, the circuit changes to open circuit. Another one is N/O, it's short for Normal Open. It means the circuit is normal open and when alarm triggers, the circuit changes to closed circuit.
How to choose N/O or N/C wiring way?
To avoid the thieves to cut the wire without alarm, N/C wiring is always used for burglar alarm zone of PIR detector, microwave detector, motion sensor, door contact switch.
And on the contrary, to avoid rats gnawed the wiring and caused the alarm, N/O wiring is always used for fire alarm and emergency alarm zones such as wiring of smoke detector, heat detector, emergency button.
Will N/C wiring circuit triggers alarm when someone short-circuit it? Will N/O wiring circuit triggers alarm when someone cut the circuit?
Yes, there is EOL resistor used to monitor the circuit. The EOL resistor value is 2.2K, 4.7K or any, depends on the alarm host. At proper working statues, the monitored resistance value of the circuit is the resistor value. At N/O circuit, if circuit opens, the resistance value is ∞, it reports alarm. If circuit closed, the resistance value is 0, it reports fault.
Likewise, for N/C wiring circuit, the circuit opens will report alarm and the circuit closes will report fault.
Low power of the detector will be reported as well.
To monitor for other vandalism, tamper-resistance wiring is used. And there is a wiring way called 2 EOL resistors.
wired detector wiring.jpg
wired detector wiring.jpg (47.91 KiB) Viewed 522 times
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