U.S. patent number 3,618,081 [Application Number 04/832,741] was granted by the patent office on 1971-11-02 for condition detection and alarm system.
This patent grant is currently assigned to Edwards Company, Inc.. Invention is credited to John T. Morrow.
United States Patent |
3,618,081 |
Morrow |
November 2, 1971 |
CONDITION DETECTION AND ALARM SYSTEM
Abstract
A condition detection and alarm system is disclosed having a
normally inactive detector relay in series in a detection circuit
with a normally open-circuited alarm sensing device that is
connected in multiple with a resistor to permit supervising of the
circuit. In response to actuation of the detector relay, an alarm
circuit becomes energized for actuation of at least one alarm
device. A single transistor switch is provided for supervising both
the detection circuit and the alarm circuit, the detection circuit
being supervised in a biasing circuit for the transistor, and the
alarm circuit being supervised in the output circuit of the
transistor. Failure of the transistor to provide an output is
manifested as a trouble condition.
Inventors: |
Morrow; John T. (Old Greenwich,
CT) |
Assignee: |
Edwards Company, Inc. (Norwalk,
CT)
|
Family
ID: |
25262505 |
Appl.
No.: |
04/832,741 |
Filed: |
June 12, 1969 |
Current U.S.
Class: |
340/506; 340/513;
361/170; 340/693.2 |
Current CPC
Class: |
G08B
29/10 (20130101); G08B 29/04 (20130101) |
Current International
Class: |
G08B
29/00 (20060101); G08B 29/10 (20060101); G08B
29/04 (20060101); G08b 029/00 () |
Field of
Search: |
;340/409,412,251
;317/148.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Mooney; Robert J.
Claims
What is claimed is:
1. A condition detection and alarm system having at least one
normally inactive detection relay serially coupled in a detector
circuit including a plurality of normally open sensing devices
coupled in parallel with a supervisory resistor, and a plurality of
normally inactive alarm-sensing devices coupled in parallel in an
alarm circuit subject to activation by the detector devices wherein
the improvement comprises:
a. means including a normally conducting transistor for supervising
both the detector circuit and the alarm circuit wherein the
detector circuit is normally checked for continuity in the base
circuit for the transistor and the alarm circuit is checked for
continuity in the collector-emitter circuit of the transistor,
b. means including a normally energized relay having its winding
connected in the collector-emitter circuit of the transistor
deenergized for manifesting failure of continuity in both the
detector circuit and the alarm circuit by a cutoff of the
conductance of the transistor,
c. a normally energized power failure relay, having a front contact
serially coupled in the collector-emitter circuit of the
transistor, deenergized upon failure of a commercial source of
power to remove the continuity of the transistor circuit; and
d. a standby source of energy coupled to the system upon
deenergization of the power failure relay.
Description
While the invention is subject to a wide range of applications, it
is especially suited for use in a condition detection and alarm
system wherein both a condition-sensing detection circuit and an
alarm circuit are supervised, and the invention will be
particularly described in that connection.
It is a requisite in a fire alarm system for use in a public
building, such as a school, for example, that fire-sensing
detection circuits and alarm circuits be supervised by checking
their continuity. Such a system may have a detection circuit for
one or more normally open-circuited, condition-sensing devices, and
may have an alarm circuit having one or more normally inactive
alarm devices, such as bells, connected thereto for use in
automatically sounding a general alarm in response to an abnormal
condition sensed by the detection circuit. A sensitive supervisory
relay is normally included in series in each of these circuits and
is maintained energized by a relatively low level of energization
of the associated circuit for supervisory purposes, while a
detector relay requires a higher level of energization. The use of
marginal relays in this manner produces operating problems due to
voltage fluctuation.
An object of the present invention is to provide a
condition-sensing and alarm system having improved supervisory
control.
SUMMARY OF INVENTION
The present invention provides a condition-sensing and alarm system
having a normally inactive detector device in a detection circuit
and having a normally inactive alarm circuit controlled by the
detection device. A single solid-state switching device is
controlled partly by the detection circuit and partly by the alarm
circuit to deliver an output for manifesting trouble in the
continuity of these circuits.
For a better understanding of the present invention, together with
other further objects thereof, reference is had to the following
description, taken in connection with the single FIGURE of the
accompanying drawing.
With reference to the accompanying drawing, terminals (BX) and (CX)
are connected to an alternating current commercial source of power,
thus these terminals are energized except under commercial power
failure conditions. This alternating current energy is applied
through a transformer 10, full-wave rectifier 11 and front contact
12 of a power failure relay K1 to direct current power supply
terminals (+) and (-) to provide a power supply for the
condition-sensing and alarm system. A standby battery 13 can be
provided as illustrated to be connected by back contact 12 of relay
K1 to the direct current power supply terminals in case of failure
of the commercial source of power.
The detection circuit that is supervised comprises wires 14 and 15
and includes a normally inactive detector relay K3 in series in the
circuit. The alarm circuit that is supervised includes wires 16 and
17 having a plurality of alarm devices 18 connected thereto.
A single transistor switch 19 is used for supervising both the
detection circuit and the alarm circuit. It has its bias determined
by the detection circuit and has a supervisory device in the form
of relay K4 connected in its output circuit.
Relay K4 is normally energized dependent jointly upon continuity
being maintained in both the detection and the alarm circuits to
deliver an output of the transistor 19. If either of these circuits
becomes open circuited, the relay K4 becomes deenergized to
manifest a trouble condition and cause the energization of a
trouble lamp 20.
Considering the structure of the supervised circuits more
specifically, the detection circuit has a plurality of fire-sensing
devices 21 connected in multiple across the wires 14 and 15. These
devices 21 are normally open circuited but close their contacts
upon sensing an abnormal condition such as a fire. Connected in
multiple with the sensing devices 21, is a resistor 22, which
normally limits the current flow in the detection circuit. This
circuit extends from (+), including wire 14, resistor 22, wire 15,
winding of relay K3 and resistor 23, to (-). Because of the
resistor 22 being in series in the circuit just described, the
circuit is energized at a low level which does not actuate relay K3
to close its front contacts.
The detection circuit just described also serves as a bias circuit
for transistor 19 in that a desired level of energization is
applied from this circuit to the base of transistor 19 to maintain
that transistor normally turned on, dependent upon continuity in
the detection circuit just described. OUtput of the transistor 19
to energize the supervisory relay K4 is also dependent upon
continuity in the alarm circuit extending from (+), including back
contact 24 of relay K2, wire 17, diode 25, wire 16, front contact
26 of relay K1, winding of relay K4 and collector-emitter circuit
of transistor 19, to (-).
Relay K4 is therefore maintained normally energized in accordance
with continuity in both circuits, because it can be energized in
the output circuit of the transistor 19 only provided the alarm
circuit continuity is maintained, and the transistor 19 can be
turned on only provided there is continuity in the detection
circuit. If either of these circuits should become open circuited,
the relay K4 would become dropped away, and the dropping away of
that relay would close a circuit for energizing the trouble lamp 20
through front contact 27 of relay K1 and back contact 28 of relay
K4. A diode 29 is connected across the winding of relay K4 to
provide that this relay will not be dropped away due to a momentary
line circuit interruption, and also to protect the transistor 19
from an inductive surge generated by the winding of relay K4.
It will be noted that trouble lamp 20 is subject to energization
either upon the dropping away of the supervisory relay K4 as
described, or upon the dropping away of the power failure relay K1
to close back contact 27. A trouble buzzer 29 is connected in
multiple with the trouble lamp 20 through a trouble switch 30 so as
to provide an audible manifestation of detection of trouble. The
buzzer 29 can be silenced by actuation of the switch 30 to its
left-hand position.
If a sensor 21 becomes actuated to close its contacts, the resistor
22 is shunted out of the detection circuit, and thus sufficient
current flows in the winding of relay K3 to cause that relay to
become picked up. Upon picking up, relay K3 closes a stick circuit
including its front contact 31 and cancels button CPB to maintain
relay K3 in its picked-up position. The picking up of relay K3
causes the picking up of a repeater relay K2 upon the closure of
front contact 32 of relay K3, and the picking up of relay K2 pole
changes the alarm circuit so as to render the alarm devices 18
active. Each alarm device 18 (such as a bell or horn) thus becomes
energized through front contact 33 of relay K2, wire 16, winding of
device 18, a diode 34, wire 17 and front contact 24 of relay K2.
The shifting of contacts 33 and 24 of relay K2 thus pole changes
the alarm circuit and removes the shunt of the alarm devices 18 by
the diode 25.
After the sensors 21 have been restored to their normal conditions,
the actuation of cancel push button CPB can become effective to
cause relay K3 to be restored to its normally dropped-away
position. This causes the dropping away of relay K2 to restore the
alarm circuit to its normal polarity of energization.
While there has been described what is at present considered to be
the preferred embodiment of the invention, it will be obvious to
those skilled in the art that various changes and modifications may
be made therein without departing from the invention.
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