Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
2000-02-24
2003-05-20
Pope, Daryl (Department: 2632)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S507000, C340S533000, C340S003100
Reexamination Certificate
active
06567001
ABSTRACT:
BACKGROUND OF THE INVENTION
In a typical alarm system within a building, such as a fire or burglar alarm system, many types of sensors, detectors, lights, strobes, sounders and other associated devices may be located throughout the building as part of the system. Groups of these devices are often wired together along one or more pairs of electrical lines used to supply power and communications to the devices. A group of such devices wired on a commonly shared pair of lines is often referred to as a line of devices. Many separate lines of devices typically connect back to a control panel that controls the overall operation of the alarm system. A line of devices is usually associated with a certain zone of the building and/or a certain type of device. For example, one floor of a multi-story building may have all of its smoke detectors wired together on a line that connects back to the control panel.
In the alarm system, it is important to monitor the integrity of the line of devices to ensure that, in the case of an emergency, the devices will function properly. Such monitoring has been performed in the prior art using a supervisory current, as illustrated in FIG.
1
.
An alarm system is provided generally as
10
. The system
10
has a plurality of alarm devices
12
-
1
,
12
-
2
,
12
-
3
,
12
-
4
electrically and alternately connected to a first voltage source
14
and a second voltage source
26
, and to respective zero volt connectors
44
and
28
, by electrical conductor
16
. The alarm devices
12
-
1
through
12
-
4
are wired together in a parallel configuration. The system
10
also includes a first switch
18
and a second switch
20
. Each switch
18
,
20
can determine which source
14
,
26
will power the alarm system
10
.
The wiring integrity of the system
10
can be monitored in a supervisory state. When the system
10
monitors the integrity of the alarm devices
12
and electrical conductors
16
in a supervisory state, the first switch
18
engages an up position
22
while the second switch
20
engages a down position
42
. Such contacting of the switches
18
,
20
allows a supervisory current to travel from the first source
14
to a first zero volt connection
28
. From the first voltage source
14
, the supervisory current travels through an end-of-line resistor
30
and through a resistor
32
prior to reaching the first zero volt connection
28
. In the supervisory state, alarm devices
12
-
1
,
12
-
2
,
12
-
3
,
12
-
4
are inactive and draw a minimal amount of current from the first voltage source
14
.
The voltage across the resistor
32
, which indicates the level of current through conductor
16
, is monitored by a wire integrity sensor
34
. If the voltage within the resistor
32
remains relatively constant, as compared to a reference voltage
36
, a status signal can be sent to a controller
38
indicating a proper line integrity of the system
10
. The controller
38
can then indicate to a user that the wiring of the system
10
contains no breaks. In the case where the voltage remains constant, the wire integrity sensor
34
can continue to monitor the voltage across the resistor
32
. A voltage drop across the resistor
32
, as compared to the reference voltage
36
, can indicate a problem in the electrical conductors
16
which prevents current from flowing to the alarm devices. If the wire integrity sensor
34
detects a drop in the voltage within the resistor
32
, the wire integrity sensor
34
sends a status signal to the controller
38
, indicating that there is a break in the line integrity of the system
10
. The controller
38
can then indicate to a user the existence of a break in the wiring integrity of the system
10
.
During an alarm state, the first switch
18
engages in the down position
24
while the second switch
20
engages the up position
40
. Contacting of the switches
18
,
20
in this manner allows an alarm-mode current to travel from a second voltage source
26
to a second zero volt connection
44
. The second voltage source provides 24 volts to the system
10
. In an alarm state, the alarm devices
12
-
1
,
12
-
2
,
12
-
3
,
12
-
4
are active and draw significant current from the second voltage source
26
. Current from the second voltage source
26
travels through each alarm device
12
-
1
,
12
-
2
,
12
-
3
,
12
-
4
and toward the second zero volt connection
44
. To monitor the system
10
during an alarm state, the system
10
includes a monitor
46
and a fuse
50
.
During an alarm state, the monitor
46
compares a measured voltage of the system
10
with a reference voltage
48
of approximately zero volts. In the case where the fuse
50
remains intact, the monitor
46
measures zero volts. The monitor
46
, in detecting no difference between the measured voltage and the reference voltage
48
, can then send a status signal to the controller
38
indicating that the fuse is intact.
In the case where one of the alarm devices
12
-
1
through
12
-
4
develops a short circuit during an alarm state, the alarm device will draw an increased amount of current, thereby leading to an over current situation in the system
10
. The over current in the system
10
, in turn, causes the fuse
50
to trip or blow. With the fuse tripped, the monitor
46
will measure 24 volts from the system
10
and compare this measured voltage to the reference voltage
48
. In the case of a tripped fuse, the monitor
46
, in detecting a difference between the measured voltage and the reference voltage
48
, sends a status signal to the controller
38
to indicate a short circuit in one of the alarm devices
12
-
1
through
12
-
4
. The controller
38
, in turn, can indicate to a user the existence of a short circuit in one of the alarm devices. Monitoring of an alarm system
10
in this manner, during an alarm state, has been performed using the Simplex 4010 system (Simplex Time Recorder, Gardner, Mass.).
SUMMARY OF THE INVENTION
While the aforementioned monitors can determine line integrity during a supervisory state and a short circuit in an alarm device in an alarm state, the monitors do not indicate where in the system a break has occurred during a supervisory mode or whether a break has occurred in the alarm mode. The monitors also fail to indicate which alarms are inoperative due to a break in the wiring of the system or due to a failure of an alarm device. Information regarding the location of the break and the operability of the alarms can be useful to emergency personnel. Without alarm notification, occupants may remain in a building during an alarm state, for example. Knowledge of where a break in line integrity occurs can provide emergency personnel with information regarding which occupants should be personally warned of an alarm state in a building.
During a fire emergency in the aforementioned alarm systems, the electrical conductors and alarm devices themselves are subject to damage caused by a fire or the resulting heat. Certain types of Circuit Integrity wiring can withstand direct flame for up to two hours. The characteristics of the wire, however, will change with this exposure. For example, the resistance of the wire will increase when exposed to direct flame. With such a change in the wire, the alarms used to warn of the fire may become inoperative. The change in resistance of the wiring, leading to alarm failure, cannot be detected with the current alarm systems.
The present alarm system detects the failure of an alarm device connected to the system. The alarm system will also detect not only a break in the line integrity of the system, but the location of the break. Furthermore, the alarm system can detect the change in resistance of the wiring in the system caused by exposure to heat which, in turn, can predict the potential failure of an alarm system.
The alarm system can include an electrical conductor, a plurality of alarm devices powered from the electrical conductor and a load sensor which senses the electrical load on the electrical conductor to indicate failure of one or more dev
Barrieau Mark P.
Brooks Jeff
Capowski Anthony J.
Hamilton Brook Smith & Reynolds P.C.
Pope Daryl
Simplex Time Recorder Co.
LandOfFree
Fire control panel monitoring for degradation of wiring... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fire control panel monitoring for degradation of wiring..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fire control panel monitoring for degradation of wiring... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3089946