Fire Alarm System Circuit Bus Short Circuit Handling Methods
When a certain circuit bus of the fire alarm system experiences a short circuit and the current between wires is too high, the controller emits sound and light alarms, while displaying a short circuit on the LCD screen in Chinese (see the image below). The printer and historical records will log the corresponding fault information.
Image source: Dangning Fire Network
General handling methods for bus short circuits:
At this point, the system should be immediately powered off, and a professional technician should inspect the wiring. Only after eliminating the short circuit fault point can the system be powered back on, returning it to monitoring status, and detailed records should be kept.
Specific handling reference methods for circuit signal line short circuits:
1) Disconnect the short-circuited circuit bus from the fire alarm controller;
2) According to the circuit bus construction drawings, segment the circuit. Use a multimeter to measure whether each segment of the circuit bus is short-circuited;
3) Measure the shorted parts further until narrowed down to a specific point or range for repair or replacement;
4) Measure the circuit to ensure it is not short-circuited or grounded, then reconnect to the fire alarm controller.
Common causes of circuit signal line short circuits:
1) Damaged wiring;
2) Water ingress into the equipment;
3) Equipment damage.
Handling Methods for Fire Alarm System Field Device Faults
For areas already logged in the fire alarm system, when there is an internal fault in the field bus device (detector failure), poor contact between the device and the base, poor contact between the device base and the bus, substandard signal line construction (communication faults), unconnected 24V power supply to the module, broken input signal line or 24V line to the input module, short circuit or break in feedback signal or 24V line of the output module, short circuit or break in control lines of the output module (output line faults), etc., the fire alarm controller will emit a fault sound and light alarm. At this time, the yellow fault indicator light on the panel will illuminate, and the LCD screen will display the total number of faults, sequence number, and the number, type, alarm time, and installation location of the fault (see the image below). The printer and historical records will log the relevant fault information.
Image source: Dangning Fire Network
General Handling Methods for Fire Alarm System Field Device Faults:
1. Press the “Silence” button, the fire alarm controller sound will turn off, and the “Silence” indicator light will illuminate.
2. Confirm and judge based on the secondary code, location, and date and time information displayed.
3. If it is confirmed to be a fault of the front-end components on site, simple inspection and maintenance should be considered promptly:
1) For a single fire detector (fire module) fault alarm, check if the connection between the base and the bus is secure, whether the detector (module) is reliably connected to the base, and if there are duplicate codes.
2) If multiple fire detectors (fire modules) report faults simultaneously, there may be a broken line somewhere.
4. If the fault cannot be eliminated temporarily due to special reasons, the shielding function provided by the fire alarm system can be used to temporarily isolate the device from the system to maintain normal system operation. After the fault is eliminated, cancel the shielding function to restore the device. The fire alarm system will automatically return to normal monitoring status.
5. After the fault is eliminated, the fire alarm system will automatically return to monitoring status.
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Source: Fire Engineering
