US3651330A

US3651330A - Dual alarm and master box control circuit

Info

Publication number: US3651330A
Application number: US106515A
Authority: US
Inventors: Frederick Vincent Hayes
Original assignee: Gulf and Western Systems Co
Current assignee: Gulf and Western Systems Co
Priority date: 1971-01-14
Filing date: 1971-01-14
Publication date: 1972-03-21
Anticipated expiration: 1989-03-21

Abstract

The circuit uses diodes to direct half-wave alternating current signals through a signaling relay when the remote station is closed, and through the master box tripping mechanism when the remote station is open. This circuit therefore provides positive operation without using resonant circuits, and insures positive operation even when the primary power source is defective. An associated circuit tie-in between a master station tripping mechanism and its independent primary power source and a remote station actuation and its independent power source is provided whereby the circuit is operative from the primary power source when such source is normally available without effecting the secondary power source, but where the secondary power source is introduced into the circuit after a predetermined time delay if the primary power source is unavailable for any reason. The secondary power source is delayed approximately 1/4 second using a time delay relay to allow the primary source time to trip the master box when the primary source is available.

Description

[ 51 Mar. 21, 1972 [54] DUAL ALARM AND MASTER BOX CONTROL CIRCUIT [72] Inventor: Frederick Vincent Hayes, Medway, Mass.

[73] Assignee: Gulf 8: Western Systems Company, New

York, N.Y.

[22] Filed: Jan. 14, 1971 [21] Appl. No.: 106,515

[52] U.S.'Cl ..307/64, 340/215 Primary ExaniinerRobert K. Schaefer Assistant Examiner-William J. Smith Attorney-Meyer, Tilberry and Body 57 ABSTRACT The circuit uses diodes to direct half-wave alternating current signals through a signaling relay when the remote station is closed, and through the master box tripping mechanism when the remote station is open. This circuit therefore provides positive operation without using resonant circuits, and insures positive operation even when the primary power source is de- +-TO CONTROL STATION fective. An associated circuit tie-in between a master station [51] Int. Cl. ..l-l02g 9/00 v. I tripping mechanism and its independent primary power [58] Field of Search ..307/64, 340/ 164, 23136229979, Source and a remote station actuation and its independent power source is provided whereby the circuit is operative from the primary power source when such source is normally [56] References cued available without effecting the secondary power source, but

UNITED STATES PATENTS where the secondary power source is introduced into the circult after a predetermined time delay if the primary power 3,440,492 Carmody X source is unavailable for any reason The econdary power 3,505,531 4/1970 Wattson ..307/64 soul-Ce i d l ed roximately /4 second using a time delay 3,515,896 6/1970 Swing et al ..307/64 l relay to allow the primary source time to trip the master box m H g V H when the primary source is available.

v 1 0 Claims, 2 Drawing Figures PRIMARY F-OWER- SOURCE i. N l5 i|2 H5 I11 VIAC I? I4 20 W Y t Pmmrmmmn SHUNT TRIP MASTER BOX POWER FROM CITY OR OTHER PRIMARY SOURCE PRIMARY POWER SOURCE LOCAL ALARM 3 CONTROL MANUAL CIRCUIT SWITCH I 4 5 av I I GOcps HEAT WATER DETECTOR DETECTOR F I G- I CODED ALARM F I G.2

*TO CONTROL STATION FREDERI BYI 7%? 7792/ AT ORNEY S IINVENTOR CK HAYES DUAL ALARM AND MASTER BOX CONTROL CIRCUIT DISCLOSURE Heretofore, it has been known that there have been many and various methods and apparatus for providing dual alarm and master box control circuits for fire alarm or emergency situations. In the Dualarm system heretofore made by Gamewell of Gulf and Western Systems Company, the system performs two fire alarm functions. When the remote control station is pulled, it causes the operation of local alarm devices on the protected premises in which the cabinet is located, and at the same time causes the transmission of an alarm to fire headquarters from the connected master fire alarm box. The system has been characterized because the disablement of the local alarm circuit will not prevent transmission of the alarm to fire headquarters if a remote-control station is operated. And conversely, neither will an opening of the master fire alarm box circuit prevent sounding of the local alarm devices from remotecontrol station operation. However, this prior art circuit did not provide for dependable operation of the tripping mechanism of a master fire alarm box when the fire alarm box circuit was open. This prior art fire system utilized a resonant circuit to actuate the alarm bell contactor in the event that the master box trip mechanism did not operate when a remote station was operated. The defect in this system related to the resonant circuit having to be adjusted or tuned so that when the impedance of the trip coil was inserted in series with the circuit, by opening of the remote-control station, the current in the signal relay was dropped sufficiently to make the armature drop away and close its contacts. Resonant circuits are expensive and tuning thereof to insure operation is not always reliable.

Therefore, the general object of the present invention is to. overcome the deficiencies in this and other prior art fire or emergencies systems arranged to energize local alarm devices and to energize the coil of a master fire alarm box tripping mechanism in response to the opening of a single normally closed circuit which is inherently reliable, relatively simple and inexpensive.

A further object of the invention is to provide a dual alarm system arranged to energize local alarm devices and to energize the trip coil of a master box in a normally energized fire alarm circuit, in response to the opening of a single normally closed circuit, regardless of the energization of the fire alarm circuit at the master station.

A further object of the invention is to provide an alarm system in which a box tripping coil connected in a normally closed fire alarm circuit is shunted by a normally closed circuit to provide energization of the coil, in combination with a local alarm relay normally energized by current from a local source through the closed circuit so that when the closed circuit is opened, the alarm relay will be deenergized and the tripping coil will be energized, regardless of the current flow in the normally closed fire alarm circuit.

A further object of the invention is to provide an alarm system arranged to normally energize a local alarm relay by half-wave current of one polarity through a pair of normally closed contacts, and to energize the coil of a master box trip mechanism by the opposite half-wave current when the contacts are open.

A further object of the invention is to provide an alarm system in which a tripping coil connected in a normally energized fire alarm circuit is shunted by a normally closed circuit to prevent energization of said coil, in combination with a local alarm relay normally energized by half-wave current of one polarity through the closed circuit, so that when the closed circuit is opened, the alarm relay will be deenergized and the tripping coil will be energized by the opposite halfwave current, and including a diode arranged so that a short circuit around the tripping coil will not prevent deenergization of the alarm relay when the closed circuit is opened.

Another object of the invention is to provide an alarm system arranged. to energize local alarm devices and to energize the coil of a master fire alarm box tripping mechanism, in response to the opening of a single normally closed circuit in combination with diodes being arranged so that a short circuit around the coil will not prevent energization of the alarm devices in response to the opening of the normally closed circuit.

The aforesaid objects of the invention and other objects which will become apparent as the description proceeds are achieved by providing an alarm system comprising a master fire alarm box tripping mechanism, a primary power source to supply primary electrical power to the mechanism, at least one remote station switch which when actuated directs the power means to actuate the mechanism, a secondary power means at each remote station and circuit means associated between the mechanism and the remote stations, the circuit effecting actuation of the mechanism with the secondary power means whenever the primary power means is inoperative. The circuit means comprises a closed shunt loop with the master box tripping mechanism, a first diode in the shunt loop between the tripping mechanism and the remote station switch to normally prevent flow of current from the secondary power means into the primary circuit means, a second diode between the secondary circuit means and the remote station switch to normally prevent flow of current from the primary power means into the secondary circuit means. The second diode also prevents flow of current from the secondary power means into the tripping mechanism, on the negative part of the AC provided by the secondary power source; and relay means dependent upon energization by the secondary power means when the remote station switch is opened acting to bypass one of the diodes and actuate the tripping mechanism after a predetermined time delay when the primary power means is inoperative.

For a better understanding of the invention reference should be had to the drawings wherein:

FIG. 1 is a block diagram of a typical dual alarm system configuration; and

FIG. 2 is a schematic electrical wiring diagram of the improved control circuit of the invention.

The reason that it is of importance to be able to operate the master box tripping mechanism, even though there is no current flowing in the fire alarm circuit at the time, is that the equipment at the fire alarm headquarters and the mechanisms in the fire alarm box provide for transmission of a box signal over one side of the fire alarm line to ground in the event of a break in the fire alarm line. This is typical and the prior art has utilized this type of system. Hence, the novel circuit defined hereinafter is primarily concerned only with operating the master box tripping mechanism when the primary power source is inoperative although it should be understood that the circuit is applicable to any need for being able to switch from a primary to a secondary power source.

In effect, the overall circuit configuration is illustrated in F IG. 1, and comprises the control circuit of the invention illus trated by block 1, a shunt trip master box indicated by block 2, local alarm devices indicated by block 3, and inputs from signal originating devices to the control circuit 1 such as a heat detector 4, a water detector 5, and a manual switch 6.

In the typical system, the current for operation of the tripping coil in the master box is supplied from a municipal circuit and normally is a miliampere DC source. Alternating current, volts, 60 cycles is an input to the control circuit, which normally is located at the protected property and is used primarily to sound audible devices such as bells and/or horns.

The alarm system preforms two functions. When a manual station heat detector 4, water detector 5, or manual switch 6 is operated, local alarm devices (bells or horns) 3 are sounded throughout the protected premises. Simultaneously, a signal is transmitted to the shunt trip master box 2 through the control circuit 1.

The double-ended arrow 7 in FIG. 1 represents the fact that a direct current from the shunt-trip master box 2 flows in a series of closed circuits to all remote switches in the overall system. There might be as many as 50 remote switches in one control circuit associated with one master box, as an example. This closed loop constitutes a shunt across the trip magnet of the master box. When any signaling devices are operated the shunt loop is opened and the master box trips, sending its appropriate signal, normally a coded signal, to a receiver of any appropriate type in the fire department or other emergency headquarters.

Referring now to FIG. 2 showing the overall schematic wiring of the improved circuit, the numeral represents a remote station switch corresponding to switch 6 in FIG. I, normally closed which is of the pull type, or the type conventionally seen and associated with emergency signaling devices. The switch 10 effectively closes a circuit forming a shunt around a trip coil 12 in a shunt trip master box indicated by block 2. The trip coil 12 is connected in series with a normally energized master fire alarm circuit 16 which is actuated from a primary source 18, so that when the remote station switch 10 is opened, the trip coil 12 will be energized by the current normally flowing from source 18 into the primary alarm circuit 16. The box 2 further includes a holding coil 14, for trip coil 12, a pair of normally closed contacts and 17, and a normally open contact 19. When the switch 10 is opened the shunt is opened and holding coil 14 drops out. If power source 18 is operative trip coil 12 is actuated to simultaneously open contacts 15 and 17, close contact 19 and releases the master box coding mechanism to effect the transmission of a coded message to the central office receiving equipment.

CONTROL CIRCUIT A signaling relay 24 is normally energized by half-wave current from transformer 26 through the loop including the remote station switch 10 in the shunt loop. A diode 28 is provided in the shunt loop between the remote station switch 10 and the trip coil 12 so that the half-wave current which flows through the signal relay 24 cannot flow through the trip coil 12 when the remote station switch 10 is opened to assure deenergizing of the relay 24. The circuit further includes a second diode 30 with a bypass line including contact 32 therearound. The relay 24 also includes a bypass line incorporating a diode 34.

lt is an important feature of the invention that because of the

diodes

28 and 30, neither half-wave can, immediately energize the trip coil 12 when the remote station switch 10 is open. The following sequence of events takes place when switch 10 is opened:

1. Relay 24 drops out, which causes the coil of a time delay relay 36 to become energized through its direct connection through a now closed contact 40 to the input secondary power source 20.

2. The time delay of relay 36 is an inherent electrical characteristic thereof, and can be between to 1 second to meet the objects of the invention. When the time delay relay 36 times out, it closes contact 32 around the diode 30 as indicated by the dotted line 32a.

3. This short-circuits diode 30 and if the primary power source 18 is inoperative and coil 12 has not tripped, half-wave current from transformer 26 can fiow from the transformer terminal 26b through master box holding coil 14, trip contact 17, the master trip coil 12, trip contact 15, diode 28, relay contact 32, diode 34, limiting resistor 38, and back to the other side of the transformer at terminal 26a.

4. In this way the coil 12 is actuated by the secondary power source 20, which immediately causes contacts 15 and 17 to open and contact 19 to close to isolate the control circuit from the master box 2 after coil 12 trips. Another normally open contact 42 on time delay 36 closes to connect a filter capacitor 44 and shunting resistor 46 to smooth out the half-wave current applied to the trip coil.

5. Even through there is no power from source 18, the tripping of coil 12 by the secondary source actuates the alarm 16 as per the conventional system defined above.

The diode 34 is to eliminate the impedance of the coil 24 from the energizing circuit in this actuation arrangement of the trip coil 12 by the secondary power source 20. The transformer 26 is designed in this circuit as having 1 15 volts on the primary and 48 volts on the secondary. A resistor 38 is provided in this circuit to limit the current through contact 32 and diode 34 when the switch 10 is again closed until relay 23 has had time to pick up and relay 36 to drop. As soon as the relay 36 drops upon reclosing of switch .10, and contact 32 thereby opens, the current will be normal through the relay coil 24 in one direction and blocked by diode 30 in the other direction.

It should thus be understood that the relay coil 24 acts upon normally

open contacts

40 and 41, as indicated by the dotted lines 40a and 41a, and that when the relay coil 24 drops out on the opening of switch 10, the normally

open contacts

40 and 41 will become closed. Naturally, the closing of contact 40 causes the actuation of the time delay relay 36 and its associated

contacts

32 and 42. The closing of normally open contact 24 brings into play a capacitor 44 which acts as a filter to smooth the half-wave current applied from the secondary source 20 to the trip coil 12 when the primary power source 18 is defective or inoperative for some reason. This capacitor is connected across the circuit only when the time delay relay coil 36 is continuously energized for a time interval equal to the timing adjustment of the time delay relay. A resistor 46 is connected across capacitor 44 to provide a discharge path for the capacitor when the time delay relay 36 is deenergized and contact 42 is re-opened to its normal position.

Also, when remote switch 10 is opened, causing contact 41 to close, a coil 48 is energized to act on its normally opened contact 50 to actuate the local alarm devices 3 at the protected premises. The local alarm devices 3 can be coded or not according to the need and will be actuated until switch 10 is again closed.

Naturally, it should be understood that if the primary power source is properly operative, the same sequence of events defined above will occur to actuate the local alarm devices 3, but because the power source 18 is available, the secondary source 20 will not come into play in connection with the actuation of the trip coil 12 as contacts 15 and 17 will be immediately opened prior to the actuation of the time delay relay 36. If both power sources fail, the master box tripping mechanism and the local alarm devices are inoperative.

SUMMARY Hence, it is seen that the objects of the invention have been achieved by a reliable circuit utilizing a pair of

diodes

28 and 30 operating in conjunction with each other around a remote switch 10 in a shunt circuit arrangement with the master trip coil 12. Under the normal conditions, each

power source

18 and 20 will be properly in balance, and no alarms will be actuated. Upon the opening of switch 10, however, relay 24 drops out closing

contacts

40 and 41. This actuates time delay relay 36 to close contact 32 providing a power source around diode 30 and to close contact 42 to convert the filter capacitor 44 and shunting resistor 46 into the circuit. At the same time, this energizes coil 48 to close contact 50 to actuate the local alarm devices 3. With the shunt circuit including switch 10 open, if primary power source 18 is operative, the coil 12 will be immediately energized causing actuation of alarm 16. If the primary power source 18 is inoperative, power will pass from source 20 through contact 32 to the trip coil 12 for actuation a shunt primary circuit means normally shunting the power from the primary power means around the mechanism,

at least one normally closed remote station switch in the shunt circuit,

secondary power means to each remote station switch,

secondary circuit means associated with the mechanism and the remote station switch to directly actuate the mechanism with the secondary power means whenever the primary power means is inoperative and the remote station switch is opened, and

means to provide a predetermined time delay after said remote station switch is opened before said secondary circuit means is actuated.

2. A system according to claim 1 where the tripping mechanism includes normally closed switch means connecting the mechanism to the secondary circuit means, said switch means opened by the actuation of the tripping mechanism to isolate the secondary circuit means from the tripping mechanism.

3. An alarm system according to claim 1 where the circuit means includes a first diode in the shunt circuit between the mechanism and the remote station switch to normally prevent flow of the current from the secondary power means into the primary circuit means, a second diode between the secondary circuit means and the remote station switch to normally prevent flow of current from the primary power means into the secondary circuit means, and relay means dependent upon energization by the remote station switch being closed to bypass one of the diodes when the remote station switch is opened.

4. The system according to claim 3 where therelay means comprises a first signaling relay normally energized by the secondary power means through the remote station switch, normally open switch means closed by said relay dropping out upon the opening of said remote station switch, a local alarm actuated by the closing of said switch means, and a time delay relay actuated by the closing of said switch means, and additional switch means actuated by said time delay relay to bypass said one diode.

5. A system according to claim 4 where the time delay relay has a time delay period of between to 1 second.

6. A system according to claim 4 which includes a third diode to eliminate the impedance of the signaling relay from the master box mechanism when said remote station switch is open and the primary power means is inoperative.

7. A system according to claim 6 where the secondary power means is an ACsource and provides a half-wave signal to said circuit means, and the circuit means includes a filter means to smooth out the half-wave alternating current from said secondary power means acting on the mechanism when the primary power means is inoperative.

8. A system according to claim 7 where the filter means is a capacitor and includes a discharge means associated therewith to dissipate an electrical power charge still associated therewith upon closing the remote station switch and returning the system to normal operation.

9. An alarm system which comprises a master tripping coil,

primary power means to supply primary electrical power to said coil,

a shunt circuit normally shunting the power from the primary power means around the tripping coil,

at least one normally closed remote station switch in the shunt circuit,

an alternating current secondary power means associated with said remote station switch and circuit means associated with the coil and the remote. station switch to acmate the coil with the secondary power means whenever the switch is opened and the primary power means is inoperative, said circuit means operating after a predetermined time delay and including diodes to prevent the direct electrical connection of the secondary power means to the coil until the circuit means is operative. 10. An alarm system according to claim 9 where the diode means include a first diode in the shunt circuit between the tripping coil and the remote station switch to normally prevent flow of the current from one half-wave of the secondary power means into the mechanism, a second diode between the secondary power means and the remote station switch to normally prevent flow of current from the coil into the circuit means and from the other half-wave of the secondary power source to the tripping coil, said circuit means further including means to bypass at least one diode upon opening of the remote station switch.

* l i i

Claims

1. An emergency alarm system which comprises a shunt master box tripping mechanism, primary power means to supply primary electrical power to said mechanism, a shunt primary circuit means normally shunting the power from the primary power means around the mechanism, at least one normally closed remote station switch in the shunt circuit, secondary power means to each remote station switch, secondary circuit means associated with the mechanism and the remote station switch to directly actuate the mechanism with the secondary power means whenever the primary power means is inoperative and the remote station switch is opened, and means to provide a predetermined time delay after said remote station switch is opened before said secondary circuit means is actuated.

4. The system according to claim 3 where the relay means comprises a first signaling relay normally energized by the secondary power means through the remote station switch, normally open switch means closed by said relay dropping out upon the opening of said remote station switch, a local alarm actuated by the closing of said switch means, and a time delay relay actuated By the closing of said switch means, and additional switch means actuated by said time delay relay to bypass said one diode.

5. A system according to claim 4 where the time delay relay has a time delay period of between 1/8 to 1 second.

7. A system according to claim 6 where the secondary power means is an AC source and provides a half-wave signal to said circuit means, and the circuit means includes a filter means to smooth out the half-wave alternating current from said secondary power means acting on the mechanism when the primary power means is inoperative.

9. An alarm system which comprises a master tripping coil, primary power means to supply primary electrical power to said coil, a shunt circuit normally shunting the power from the primary power means around the tripping coil, at least one normally closed remote station switch in the shunt circuit, an alternating current secondary power means associated with said remote station switch and circuit means associated with the coil and the remote station switch to actuate the coil with the secondary power means whenever the switch is opened and the primary power means is inoperative, said circuit means operating after a predetermined time delay and including diodes to prevent the direct electrical connection of the secondary power means to the coil until the circuit means is operative.

10. An alarm system according to claim 9 where the diode means include a first diode in the shunt circuit between the tripping coil and the remote station switch to normally prevent flow of the current from one half-wave of the secondary power means into the mechanism, a second diode between the secondary power means and the remote station switch to normally prevent flow of current from the coil into the circuit means and from the other half-wave of the secondary power source to the tripping coil, said circuit means further including means to bypass at least one diode upon opening of the remote station switch.