The main method for diagnosing fire plumes
Often in the practice of an adjuster of fire and security alarm systems, there are cases when the control panel periodically gives signals about a malfunction or an alarm of the detector. When the engineer comes on a call, the device behaves obediently and the loop to which complaints were received stably gives out the “norm” state, but as soon as you leave the facility, calls from the customer again come. Most often, this situation occurs in conventional fire or burglar alarm loops.
Let’s try to simply and without further ado list all the possible options when the control panel periodically issues signals about a malfunction or a detector operation:
– First of all, we turn off the problematic cable and check the resistance with a “tester”. The resistance should be stable and on average be about 30 ohms per 100 meters of the loop (for 0.4 mm copper wire).
– If the smoke loop gave a “malfunction” signal, to determine a possible poor contact in the socket of one of the detectors, it is useful to carry out the following procedure: one engineer connects the multimeter to the loop disconnected from the device in resistance measurement mode a, while the other one passes along the loop, lightly tapping for each chimney. Having stumbled upon the problematic one, you will see jumps in readings.
– If the resistance measurements did not give a result, you can measure the current by turning on the multimeter in the millimeter mode in the loop break. This method is especially useful if the device gives a “Fire” signal in the loop, and the indicator on any sensor is not lit.
– The method is as simple as possible – a faulty sensor is “calculated” by turning off the sensors one by one with simultaneous monitoring of readings, when the faulty detector is turned off, a sharp decrease in current in the loop should be recorded.
– You can still try to determine the presence of a loop leakage to the ground, for which the current is measured in the plus and minus wires of the loop. In the absence of leakage, the readings should be exactly the same.
– If everything does not help, you can try to swap the cable with another, of the same type. This will help eliminate the malfunction of the PPC itself.
– If this did not help, and the loop periodically continues to give false alarms, you can try to turn off all the sensors in the fire loop for a while and check the operation of the “clean line”. If there are no triggers, it is worth “throw” one or more sensors at a time and observe what is happening.