Operating a fire alarm system
Devices, systems, and methods for operating a fire alarm system are described herein. One device includes circuitry to determine a resistance associated with an addressable fire alarm loop during a quiescent condition, determine an expected voltage drop in the loop during an alarm condition based on a plurality of devices of the loop, and set an alarm drive voltage of a power supply associated with the loop based on the resistance and the expected voltage drop.
1. A controller for operating a fire alarm system comprising circuitry to:
determine a resistance associated with an addressable fire alarm loop during a quiescent condition based on:
a resistance of wiring associated with the loop
a respective resistance of each of a plurality of circuit breakers corresponding to a plurality of devices of the loop; and
a respective resistance of each of a plurality of portions of the loop located between devices of the plurality of devices;
determine an expected voltage drop in the loop during an alarm condition based on the plurality of devices of the loop; and
set an alarm drive voltage of a power supply associated with the loop based on the resistance and the expected voltage drop.
2. The controller of claim 1 , including circuitry to determine the resistance associated with the loop continuously during the quiescent condition.
3. The controller of claim 1 , including circuitry to determine the expected voltage drop in the loop during the alarm condition based on a respective current associated with each of the plurality of devices of the loop.
4. The controller of claim 1 , wherein a value of the alarm drive voltage is less than a value of a voltage rating of a device of the plurality of devices.
5. The controller of claim 4 , wherein a value of the alarm drive voltage is less than a value of a voltage rating of each of the plurality of devices.
6. The controller of claim 1 , including circuitry to cause the power supply to increase from a quiescent drive voltage to the alarm drive voltage responsive to an occurrence of the alarm condition.
7. The controller of claim 6 , including circuitry to cause the power supply to increase from the quiescent drive voltage to the alarm drive voltage over a particular period of time.
8. The controller of claim 1 , wherein the controller is a microcontroller associated with the loop, and wherein the controller is a part of an addressable fire alarm system control panel.
9. A fire alarm system, comprising:
a plurality of devices of a loop of the fire alarm system, wherein the plurality of devices includes a plurality of alarm devices;
a power supply associated with the loop;
a controller associated with the loop and having circuitry to:
determine a resistance associated with the loop during a quiescent condition based on:
a resistance of wiring associated with the loop
a respective resistance of each of a plurality of circuit breakers corresponding to the plurality of devices; and
a respective resistance of each of a plurality of portions of the loop located between devices of the plurality of devices;
determine an expected voltage drop in the loop during an alarm condition based on the plurality of devices; and
set an alarm drive voltage of the power supply based on the resistance and the expected voltage drop.
10. The system of claim 9 , wherein a length of the loop of the fire alarm system exceeds two kilometers.
11. The system of claim 9 , wherein the plurality of alarm devices includes audible alarm devices and visual alarm devices.
12. The system of claim 9 , wherein the controller includes circuitry to cause the plurality of alarm devices to activate responsive to a determination of an alarm condition associated with the loop.
13. The system of claim 12 , wherein the plurality of alarm devices are configured to regulate an activation current such that the activation current increases over a period of time.
14. A method of operating a fire alarm system, comprising:
determining a resistance associated with an addressable fire alarm loop during a quiescent condition based on:
a resistance of wiring associated with the loop
a respective resistance of each of a plurality of circuit breakers corresponding to a plurality of devices of the loop; and
a respective resistance of each of a plurality of portions of the loop located between devices of the plurality of devices;
determining an expected voltage drop in the loop during an alarm condition based on the plurality of devices of the loop;
setting a first alarm drive voltage of a power supply associated with the loop based on the resistance and the expected voltage drop;
determining a maintenance condition associated with the loop; and
setting a second alarm drive voltage of the power supply based on the determined maintenance condition.
15. The method of claim 14 , wherein determining the maintenance condition includes determining a disconnection of a device of the plurality of devices from the loop.
16. The method of claim 14 , wherein determining the maintenance condition includes determining an opening of a door associated with a control panel of the fire alarm system.
17. The method of claim 14 , wherein the second alarm drive voltage of the power supply corresponds to a quiescent drive voltage of the power supply.
18. The method of claim 14 , wherein the second alarm drive voltage of the power supply exceeds a quiescent drive voltage of the power supply and is exceeded by the first alarm drive voltage of the power supply.
19. The method of claim 14 , wherein the method includes reducing a current draw of a device of the plurality of devices subsequent to setting the second alarm drive voltage of the power supply.