FIRE DETECTION SYSTEM WITH TAMPERING DETECTION CAPABILITY AND A METHOD THEREOF

1 . A fire detection system having a plurality of fire detectors in a loop, wherein at one of the fire detectors comprising:

a tamper detection circuit having reactive impedance; and

a controller connected to the detection circuit, the controller comprises a processor with access to a memory storing instructions executable by the processors, which causes the controller to:

measure time taken by a voltage applied across or a current flowing through the detection circuit to reach a predefined value;

measure a time constant of the detection circuit based on the measured time taken;

detect if the measured time constant exceeds a predefined threshold; and

in response to a positive detection, detect tampering in the fire detector.

2 . The system of claim 1 , wherein in response to a negative detection and/or upon a non-detection, the controller is configured to monitor the time constant.

3 . The system of claim 1 , wherein the controller is configured to monitor tampering in the detection circuit at a predetermined interval or in real time.

4 . The system of claim 1 , wherein the controller is configured to:

issue a detection signal to turn ON or turn OFF supply of electrical power to the detection circuit; and

measure the time constant of the detection circuit upon ON or turning OFF the electrical power supply to the detection circuit.

5 . The system of claim 1 , wherein the controller is configured to:

issue a detection signal to turn ON supply of electrical power to the detection circuit;

measure a time delay in the supply of voltage or current to the detection circuit upon turning ON the electrical power supply and correspondingly measure a time taken by a capacitor associated with the detection circuit to be charged to a steady state; and

determine the time constant of the detection circuit based on the time taken by the capacitor to be charged to the steady state.

6 . The system of claim 1 , wherein the controller is configured to:

issue a detection signal to turn OFF supply of electrical power to the detection circuit;

measure a time delay in disabling the supply of voltage or current to the detection circuit upon turning OFF the electrical power supply and correspondingly measure a time taken by a capacitor associated with the detection circuit to be fully discharged; and

determine the time constant of the detection circuit based on the measured time taken by the capacitor to be fully discharged.

7 . The system of claim 1 , wherein the controller is configured to:

issue a detection signal to turn ON supply of electrical power to the detection circuit;

monitor amplitude of voltage or current associated with the electrical power being supplied to the detection circuit and a time delay in the supply of the voltage or current to the detection circuit upon turning ON the electrical power supply; and

determine and record the time constant of the detection circuit based on the monitored voltage or current and the monitored time delay.

8 . The system of claim 1 , wherein the controller is configured to:

issue a detection signal to turn OFF supply of electrical power to the detector circuit;

monitor amplitude of voltage or current associated with the electrical power being supplied to the detection circuit and a time delay in disabling the supply of voltage or current to the detection circuit upon turning OFF the electrical power supply; and

determine and record the RC time constant of the detection circuit based on the monitored voltage or current and the monitored time delay.

9 . The system of claim 1 , wherein the controller comprises a comparator that is configured to compare the measured time constant with the predefined threshold range.

10 . The system of claim 9 , wherein the controller comprises a digital to analog convertor (DAC) that is configured to:

convert a first digital signal associated with the measured time constant into a first analog signal for the comparator; and/or

convert a second digital signal associated with the measured time taken by the voltage and the measured time delay into an analog signal for the comparator.

11 . The system of claim 1 , wherein the controller is a control panel associated with the fire detection system.

12 . A method for detecting tampering in a fire detection system having a plurality of fire detectors in a loop, the method comprising:

providing a tamper detection circuit having reactive impedance in at least one of the fire detectors;

measuring, by a controller, time taken by a voltage applied across or a current flowing through the detection circuit to reach a predefined value;

measuring, by the controller, a time constant of the detection circuit, based on the measured time taken; and

detecting, by the controller, tampering in the fire detector when the measured RC time constant is detected to exceed a predefined threshold range.

13 . The method of claim 12 , wherein the method comprises the steps of:

monitoring, by the controller, tampering in the detection circuit at a predetermined interval or in real time.

14 . The method of claim 12 , wherein the method comprises the steps of:

issuing, by the controller, a detection signal to turn ON supply of electrical power to the detector circuit;

measuring, by the controller, a time delay in the supply of voltage or current to the detection circuit upon turning ON the electrical power supply and correspondingly measuring a time taken by a capacitor associated with the detection circuit to be charged to a steady state; and

determining, by the controller, the time constant of the detection circuit based on the time taken by the capacitor to be charged to the steady state.

15 . The method of claim 12 , wherein the method comprises the steps of:

issuing, by the controller, a detection signal to turn OFF supply of electrical power to the detection circuit;

measuring, by the controller, a time delay in disabling the supply of voltage or current to the detection circuit upon turning OFF the electrical power supply and correspondingly measuring a time taken by a capacitor associated with the detection circuit to be fully discharged; and

determining, by the controller, the time constant of the detection circuit based on the measured time taken by the capacitor to be fully discharged.

16 . The method of claim 12 , wherein the method comprises the steps of:

issuing, by the controller, a detection signal to turn ON supply of electrical power to the detection circuit;

monitoring, by the controller, amplitude of voltage or current associated with the electrical power being supplied to the detection circuit and a time delay in the supply of the voltage or current to the detection circuit upon turning ON the electrical power supply; and

determining and recording, by the controller, the time constant of the detection circuit based on the monitored voltage or current and the monitored time delay.

17 . The method of claim 12 , wherein the method comprises the steps of:

issuing, by the controller, a detection signal to turn OFF supply of electrical power to the detector circuit;

monitoring, by the controller, amplitude of voltage or current associated with the electrical power being supplied to the detection circuit and a time delay in disabling the supply of voltage or current to the detection circuit upon turning OFF the electrical power supply; and

determining and recording, by the controller, the RC time constant of the detection circuit based on the monitored voltage or current and the monitored time delay.

18 . The method of claim 12 , wherein the method comprises the steps of generating an alert signal upon detecting tampering in the fire detector.

19 . The method of claim 12 , wherein the controller is a control panel associated with the fire detection circuit.