Testing a fire detector sensor
AssigneeThorn Security Limited
InventorSteve Bennett
Life of this patent
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Abstract
A method is disclosed for testing the functionality of a sensor (1) of a fire detector during operation thereof. The method comprises applying a current-limited test signal to the sensor (1), the test signal being such that the impedance of the sensor is such as to absorb the current-limited test signal when the sensor is operating normally; and applying the output of the sensor to a test signal detector (7). The arrangement is such that the test signal passes the output terminal of the sensor (1) only when the sensor is not operating normally.
Claims23
A method for testing the functionality of a sensor of a fire detector during operation thereof, the method comprising the steps of:
- a) applying a current-limited test signal to the sensor, the sensor having an impedance such that sensor absorbs the current-limited test signal when the sensor is operating normally;
- and
- b) applying the output of the sensor to a test signal detector via an amplifier circuit;
- wherein the arrangement is such that, during testing, the output voltage of the amplifier circuit is substantially constant when the sensor is operating normally, and such that the test signal passes the output terminal of the sensor only when the sensor is not operating normally, whereby the test signal is amplified by the amplifier circuit thereby to provide a signal indicative of a sensor fault.
The fire detector comprising a sensor for detecting the presence of a fire, and a test circuit for testing the functionality of the sensor during operation thereof, the test circuit comprising supply means for applying a current-limited test signal to the sensor, and means for applying the output of the sensor to a test signal detector, via an amplifier circuit, wherein the sensor has an impedance such that the sensor absorbs the current-limited test signal when the sensor is operating normally, and the arrangement is such that the output voltage of the amplifier circuit is substantially constant when the sensor is operating normally, and such that the test signal passes the output terminal of the sensor only when the sensor is not operating normally, whereby the test signal is amplified by the amplifier circuit thereby to provide a signal indicative of a sensor fault.
A fire detector system comprising a control module having a means for generating and monitoring a DC signal, and a detection module having a sensor for detecting the presence of a fire, the control module and the detection module being electrically connected, the DC signal being applied to the electrical connection between the control module and the detection module for testing the integrity of the connection, wherein the control module provides a warning signal when the connection is not made.
A control module comprising a pulse generator for applying a test signal to a sensor, a DC supply voltage means, a resistive element connected to the DC supply voltage means, means for measuring the current flowing through the resistive element and means for connecting the DC supply voltage to an external circuit, wherein the means for measuring the current signals an alarm when the DC supply voltage is not connected to an external circuit.
Dependencies are inferred from the claim text.