US2278939A

US2278939A - Manual fire alarm system

Info

Publication number: US2278939A
Application number: US199594A
Authority: US
Inventors: Manfred W Muehter
Original assignee: American District Telegraph Co
Current assignee: American District Telegraph Co
Priority date: 1938-04-02
Filing date: 1938-04-02
Publication date: 1942-04-07
Anticipated expiration: 1959-04-07

Description

April 7, .1942 M. w MUEHTER 2,278,939

-MANUAL FIRE ALARM SYSTEM Filed April 2, 1938 MAI/(E BEFORE EREA K 29 8 I Z.QM

ATTORNEY Patented Apr. 7, 1942 TENT orrisca MANUAL FIRE ALARM SYSTEM Application April 2, 1938, Serial No. 199,594

5 Claims.

This invention relates generally to signaling systems and 'more particularly to annunciator circuits for use in signaling systems such as fire alarm circuits or other similar signaling systerns.

Annunciator circuits commonly comprise a number of annunciators such as visibleindicators which are responsive to signal conditions in some form of a transmission system. When the signal condition occurs, the annunciator connected to that transmission line responds to the signal and in addition controls an alarm circuit or in some manner causes an alarm circuit'to operate, thereby'directing attention 'to the visible indicator. It is desirable that the alarm operate until du notice has been taken of the operation of the visible'indicator, but such an alarm should not be continuous until restoration of the visible indicator as some annunciators do not restore for an extended period. It is further desirable that the alarm system be temporarily disconnected or otherwise disabled without requiring restoration of all of the visible indicators and without permanent disconnection of the audible signal which would prevent it being sounded to indicate activity on another indicator.

This invention provides a system wherein a common audible signal device will be sounded whenever there is actuation of any one of a group of annunciators and sounding will continue until a momentary contact push button is operated to silence the signal device. Furthermore, silencing of the audible signal will not aiiect the setting of the annunciator in any way. The principal advantage of the improved system embodying the invention is that the common signal device is invariably operated upon each successiveoperation of an annunciator.

It is an object of this invention to provide in a signal systema means for momentarily actuating a signal control means.

Another object of this invention is to provide in a signal system a visiblesignal and an audible signal, the audible signal being controlled by the visible signal. 4

A further object of this invention is to provide an annunciator system and an audible signal system controlled thereby wherein the 'audible signal will sound whenever there is actuation of the annunciator and will continue to sound until stopped by the 'operationof a mocontrols various alarm signals which may be in the form of bells. The drawing shows in particular a fire alarm system having the fire alarm boxes I, II and'III which are connected to the m'entary contact push button and wherein the silencing operation does not in any way disturb the annunciator setting.

annunciators Ill, 25 and 26. Thes annunciators are of the form shown in detail in Fig. 2 of the drawing having drops and during the period in which thadrops are operated, the relay 30 controls and operates the alarm bells 43.

Fig.2 shows the detailed construction of the annunciator H] which is shown'in the circuit of Fig. 1. The annunciator comprises the usual magnet with the cooperating armature 6 and target member 8. The contacts H, l2, l3, I8 and 19 also shown in Fig. 1, are operated by the armature 6 through the contact operating stud 2 1 and'block 28 when the armature is attracted by the magnet and pivotsabout the supporting member 1. The bracket 29 is merely used for supporting the annunciator on the ordinary central oflic panel. Target 8 is used as a visible'indication of theoperated condition of the annunicator. Fig. 2 shows the annunciator in deenergized condition but the annunciator is normally energized when used in the circuit shown in Fig. l. Deenergization of th annunciator will close contacts I2 and I3 and an instant later will open contacts I I and [2 so that a circuit is closed andthen opened in order to give the result required in the circuit shown in Fig. 1. Deenergization also closes the normally open contacts eandra.

The operation of the circuit may be illustrated by considering the operation of the annunciator N3, the annunciators 25 and 26 being the sam as annunciator ID in all particulars so that the operation of these devices will all be the same. The normal circuit of fire alarm box I can be traced from positive battery through line 1, protective resistance 5, box I, line 2, annunciator its, line 9, lin 23, back to negative battery. Since annunciator I0 is now energized, the contacts H and l2 will be closed. The fire alarm box I which may be manual or automatic is arranged to open the line circuit mentioned above and deenergize the annunciator. Contacts I I', I2 and is ar make-beiore-break contacts springs arranged in the well known manner to make the circuit through contact I3 and immediately break the circuit at contact II and when annunciator I is deenergized contacts I2 and I3 will close and the contacts II and I2 will then open. When contacts I2 and I3 close, a circuit can be traced from positive battery through the relay 30, line H, lin [6, contacts II, I2 and I3, line I4, line 20, and line 23 back to negative battery. Even though a circuit is closed through the relay 30, such closure is only momentary and relay will not operate. However, the condenser 3I and resistance 32 is shunted around the relay 30 and consequently the momentary closure of contacts II, I2 and I3 will charge the condenser 3I, the effect of which is that condenser 3I will subsequently discharge through the relay 30 and operate said relay. The operation of relay 30 closes the

contacts

34 and 35 thereby closing a circuit from positive battery through relay 30, line 38,

contacts

34 and 35, line 36, switch 31, line 24, back to negative battery, thereby closing a locking circuit for the relay. When relay I0 became deenergized, the contacts I8 and I9 were closed and when relay 30 operated, the contacts and M were closed thereby closing a circuit from positive battery through line 42, bells 43, line 44, contacts 40 and 4|, line 22, contacts I8 and I9, line 20 to line 23 and back to negative battery. Thus th relay II] is deenergized and relay 30 has operated and thereby operated the alarm bell 43 to give an audible signal which in turn calls an operators attention to the operation of the annunciator drop which operates in connection with relay I0. By momentarily pressing push button 31 the operator opens the locking circuit of relay 30 and silences the alarm.

In connection with the invention it may be desired to let the annunciator drop restore without operating the alarm bell. To do this the contacts I8 and I9 are provided to break the alarm bell circuit so that even though the contacts I I, I2 and I3 are closed by restoration of the annunciator drop, no alarm signal will be given due to the break at contacts I8 and I9. If it is desirable to actuate the alarm bell during restoration of the annunciator drops, the spring contacts I8 and I9 will be omitted. Thus when a drop is restored by closing the line at the fire alarm box the contacts II, I2 and I3 momentarily close the circuit to relay 30 which operates as before to close its energizing circuit and that of the alarm bell 43. To silence the alarm, the operator operates the switch 3'! which momentarily breaks the holding circuit of relay 30 and thereby breaks the alarm circuit at contacts 40 and 4|. It should be noted here that the operation of the momentary contact push-button 31 does not affect the settings of the annunciators and that even though the holding circuit is momentarily broken, operation of a drop will still actuate the alarm bell by charging condenser 3| to subsequently operate relay 3!].

Various modifications of this system are possible as for instance, the annunciator and audible signal can be used .in signal systems. A'different sort of annunciator may also be used such as one having a mechanical contact which would make a momentary contact when actuated in one direction only, such devices being Well known in the prior art.

I claim:

1. In combination, a transmitting station, a source of potential, an alarm connected to said source, an annunciator relay comprising a coil connected between said station and said source, a drop actuated by said relay coil, momentarily closed contacts operated by said relay coil and connected to the source, an alarm relay comprising a coil connected to said contacts and said source, a capacity shunt connected to said alarm relay coil for operating it and in series with said contacts, a pair of contacts connected in series with said alarm and operated by said annunciator relay coil for controlling said alarm, another pair of contacts connected in series with said alarm and in said alarm relay and another pair of contacts in said alarm relay and connected in series with said alarm relay coil and a switch for deenergizing said alarm relay coil.

2. In a signal system, a transmitter, a relay comprising a coil responsive to said transmitter, a drop operated by said relay coil, a second relay comprising a coil, an alarm operated by said second relay, a condenser connected in shunt to said second relay coil for energizing the same, means controlled by said first relay coil for momentarily charging said condenser to store signals whenever the drop operates and contacts connected to the alarm and controlled by said first relay coil for preventing actuation of said alarm by restoration of said drop.

3. In a signaling system, a transmission system including a number of transmitters and a source of current, a plurality of annunciators comprising operating coils connected to the transmitters and responsive to transmitted signals, an alarm circuit common to the annunciators and including said source, an alarm connected thereto, normally open alarm contacts connected to the alarm and normally open auxiliary contacts also in series with the alarm and operated by the annunciators whereby operation of an annunciator closes the auxiliary contacts, and an alarm relay circuit common to the annunciators and including annunciator contacts momentarily closed by the annunciators in response to transmitter operation, a storage circuit in series with the annunciator contacts and charged during the momentary closure of them, an alarm relay comprising an operating coil connected across the storage circuit and energized thereby for closing the alarm contacts, locking contacts closed by the alarm relay coil for applying battery and holding the relay coil in energized condition and a normally closed silencing switch in series with the locking contacts for opening the alarm relay circuit and silencing the alarm after it is actuated by each annunciator.

4. In a signaling system, a transmission system including a number of transmitters and a source of current, a plurality of annunciators comprising operating coils connected to the transmitters and responsive to transmitted signals, an alarm circuit common to the annunciators and including said power source, an alarm connected thereto, alarm contacts connected to the alarm bell and auxiliary contacts also in series with the alarm and operated by the annunciators whereby operation of an annunciator prepares the alarm circuit, and an alarm relay circuit common to the annunciators and including annunciator contacts momentarily operated by the annunciators in response to transmitter operation, a storage circuit in series with the annunciator contacts and charged during the momentary operation of them, an alarm relay comprising an operating coil connected across the storage circuit for actuating the alarm contacts, contacts operated by annunciator contacts and contacts operated by the coil of said second relay when said annunciator operates, an alarm circuit closed by certain contacts of said annunciator relay and said contacts of said second relay whereby transmitter operation initiates an alarm and restoration of said annunciator opens said alarm circuit to prevent initiation of an alarm'on restoration.

MANFRED W. MUEI-ITER.