Method and apparatus for determining proper installation of alarm devices

• US 6,459,370 B1
• Filed: 05/05/1999
• Issued: 10/01/2002
• Est. Priority Date: 11/03/1998
• Status: Expired due to Term

• Current Assignee: Johnson Controls Fire Protection LP (Johnson Controls International plc)
• Original Assignee: ADT Security Services SA (Apollo Global Management, Inc.)
• Inventors: Bonneau, Richard P., Vincent, Gary W., Laramie, Daniel, Barrieau, Mark P.
• Primary Examiner(s): POPE, DARYL C
• Application Number:
  US09/305,419
• Time in Patent Office: 1,245 Days
• Field of Search: 324/527, 324/522, 324/523, 324/524, 340/506, 340/507, 340/508, 340/511, 340/514, 340/650, 340/651
• US Class Current: 340/514
• CPC Class Codes: G08B 29/06 Monitoring of the line circuits, e.g. signalling of line faults

Abstract

Jumper and ground faults are detected within an alarm system. Jumper detection applies to devices having two or more functions (e.g., audible horn and visual strobe). When operated with a single circuit, jumpers typically remain installed in such devices to provide power to all functions. However, if the devices are installed in alarm systems equipped with multiple functions, the jumpers should be removed to allow functions to operate independently and correctly. To detect unremoved jumpers, all loops to separate functions except one are isolated. After isolation, a predetermined signal is presented to the non-isolated loop and current is compared to a reference value. If jumpers exist between this non-isolated loop and another supposedly isolated loop, the additional parallel resistance produces an abnormal signal. To perform ground fault detection, lines of devices may be sequentially isolated (i.e., disconnected) at the control panel via software control until a previously detected ground fault disappears. The line that is isolated and which causes the fault to disappear is the line containing the fault.

Claims

1. An alarm control panel comprising:

connectors to plural appliance loops;

voltage control which applies a first voltage to each loop during an alarm state and a reverse voltage to each loop during a supervisory state; and

isolation control which selectively removes the reverse voltage from selected loops to test for loop circuit faults.

2. An alarm control panel as claimed in claim 1 further comprising a detector for detecting current in each loop.

3. An alarm control panel as claimed in claim 2 which tests for jumpers connected loops.

4. An alarm control panel as claimed in claim 2 wherein the detector comprises a comparator which compares a voltage to a reference level.

5. An alarm control panel as claimed in claim 4 wherein the comparator indicates a short circuit when the voltage exceeds a first level.

6. An alarm control panel as claimed in claim 5 wherein the comparator indicates an open circuit where the voltage is less than a second level, the second level being less than the first level.

7. An alarm control panel as claimed in claim 1 which tests for jumpers connected loops.

8. An alarm control panel as claimed in claim 1 wherein the isolation control isolates all loops except one as a fault is observed.

9. An alarm control panel as claimed in claim 8 which tests for jumpers connected loops.

10. An alarm control panel as claimed in claim 1 which tests for ground faults.

11. An alarm control panel as claimed in claim 1 wherein individual loops are selectively isolated as a system fault is observed.

12. An alarm control panel as claimed in claim 11 which tests for ground faults.

13. An alarm system comprising:

a first loop coupling at least one device to a central control panel;

a second loop coupling the at least one device to the central control panel;

a first circuit coupled to the first loop, the first circuit isolating the first loop from a power supply;

a second circuit coupled to the second loop, the second circuit supplying a voltage to the second loop and detecting current through the second loop, the current indicating if a fault exists between the first and second loops.

14. A system as claimed in claim 13 wherein the current indicates jumpers connected on a device between the first and second loops.

15. A system as claimed in claim 13 wherein the detector comprises a comparator which compares a voltage to a reference level.

16. A system as claimed in claim 15 wherein the comparator indicates a short circuit when the voltage exceeds a first level.

17. A system as claimed in claim 16 wherein the comparator indicates an open circuit where the voltage is less than a second level, the second level being less than the first level.

18. A method of testing an alarm system, having plural appliance loops, for faults comprising:

applying a first voltage to each loop during an alarm state and a reverse voltage to each loop during a supervisory state;

selectively isolating loops in the system under programmed processor control by selectively removing the reverse voltage from the selected loops to test for loop circuit faults; and

monitoring the system for faults with selective isolation of the loops.

19. A method as claimed in claim 18 further comprising detecting current through a loop which is not isolated.

20. A method as claimed in claim 19 wherein current above a first level indicates a short circuit in a loop.

21. A method as claimed in claim 20 wherein current below a second level less than the first level indicates an open circuit in the loop.

22. A method as claimed in claim 19 wherein a current below a threshold level indicates an open circuit in the loop.

23. A method as claimed in claim 18 wherein the system is monitored for jumpers between loops.

24. A method as claimed in claim 18 wherein all but one loop is isolated.

25. A method as claimed in claim 18 wherein only a single loop is isolated.

26. A method for determining the location of a fault in an alarm system which includes a control panel and a plurality of loops of devices extending therefrom, the method comprising the steps of:

detecting the existence of a fault within the alarm system;

applying a first voltage to each loop during an alarm state and a reverse voltage to each loop during a supervisory state;

under programmed processor control, selectively isolating loops of devices from the program control panel by selectively removing the reverse voltage from the selected loops to test for loop circuit faults while monitoring existence of the fault; and

in a control interface, indicating to an alarm system operator the identification of the loop of devices that caused the fault.

27. A method as claimed in claim 26 wherein the fault is a ground fault.

28. A method for determining the presence of a fault in an alarm system which includes a central control panel and first and second loops extending therefrom, the first and second loops including at least one device installed therebetween, the method comprising the steps of:

isolating the first loop from a power supply;

applying voltage to the second non-isolated loop; and

detecting current through the second loop to indicate if a fault exists between the first and second loops.

29. A method as claimed in claim 28 wherein the fault is jumpers connected to the loops.

30. An alarm system, comprising:

a plurality of loops of devices in the alarm system each coupled to a supervisory control circuit, the supervisory control circuit including voltage control which applies a first voltage to each loop during an alarm state and a reverse voltage to each loop during a supervisory state; and

a processor which selectively activates supervisory control circuits associated with loops of devices while detecting a fault to selectively remove the reverse voltage from selected loops to test for loop circuit faults.

31. A system as claimed in claim 30 wherein the processor applies a first voltage to each loop during an alarm state and a reverse voltage for each loop during a supervisory state.

32. A system as claimed in claim 30 wherein the fault is detected by detecting current in a loop.

33. A system as claimed in claim 32 wherein the detector comprises a comparator which compares a voltage to a reference level.

34. A system as claimed in claim 33 wherein the comparator indicates a short circuit when the voltage exceeds a first level.

35. A system as claimed in claim 34 wherein the comparator indicates an open circuit where the voltage is less than a second level, the second level being less than the first level.

36. A system as claimed in claim 30 wherein the current indicates jumpers connected on a device between the first and second loops.

37. A system as claimed in claim 30 wherein all loops but one are isolated.

38. A system as claimed in claim 30 wherein only an individual loop is isolated.

39. A system as claimed in claim 30 further comprising a ground fault detector.

40. An alarm system, comprising:

a first loop and a second loop coupling a device installed therebetween to a supervisory control circuit; and

a processor which selectively activates supervisory control circuits associated with the loops of devices while detecting a fault between the first and second loops.

41. The alarm system as claimed in claim 40 wherein a first supervisory control circuit isolates the first loop from a power supply.

42. The alarm system as claimed in claim 41 wherein a second supervisory control circuit supplies a voltage to the second loop and detects current through the second loop, the current indicating if a fault exists between the first and second loops.

43. The alarm system as claimed in claim 42 wherein the current indicates jumpers connected on the device between the first and second loops.

44. The alarm system as claimed in claim 42 wherein the second supervisory control circuit comprises a comparator which compares a voltage to a reference level.

45. The alarm system as claimed in claim 44 wherein the comparator indicates a short circuit when the voltage exceeds a first level.

46. The alarm system as claimed in claim 45 wherein the comparator indicates an open circuit where the voltage is less than a second level, the second level being less than the first level.