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Resistor Usage in Alarm Systems

Dec 06, 2018

Resistor Usage in Alarm Systems

Line resistance (or resistance) at the End of the Line in English EOL Resistor: Line End resistance (EOL, End of Line) circuit, circuit is characterized by circuit terminal access resistance, loop of a short circuit will trigger circuit contact action, such as the system protection, circuit break or short circuit will trigger the alarm. The scientific name is wire tail resistance, resistance value of each manufacturer is not the same, installed on a variety of detectors, that is, the end of the line. In the circuit, the constant close value is connected in series and the constant open value is connected in parallel. When alarming, the main machine will detect the change of resistance value. In other words, as long as the resistance output by the detector to the host is not about 2.2k, the alarm will be given. The task is to prevent damage, you cut the wire or short circuit will alarm.

Method of line resistance connection in alarm panel

Normally closed loop (NC) : short circuit is normal, breaking the circuit panel will alarm. The disadvantage of this circuit is that if someone shorted the circuit, the probe would lose its function. Alarm host can not identify is the artificial short circuit.

Normally open circuit (NO) : short circuit alarm, break the circuit normally. The disadvantage of this circuit is that if someone cuts the line (the signal line), the probe loses its function. Alarm host can not identify the artificial segment.

Line resistance EOL: 

short circuit is normal and circuit breaking panel will alarm. This circuit has the advantage that if someone breaks the circuit (short circuit back), the alarm panel can alarm. Short circuit alarm, open circuit fault, resistance value is. 2.2k is normal. The advantage of this circuit type is: to short circuit and break the circuit to make different response, especially suitable for smoke detector and emergency button, if it is a rat bite segment or to help things and tear, alarm panel feedbacks the circuit fault.