US2028653A - Fire alarm system - Google Patents

Fire alarm system Download PDF

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Publication number
US2028653A
US2028653A US538568A US53856831A US2028653A US 2028653 A US2028653 A US 2028653A US 538568 A US538568 A US 538568A US 53856831 A US53856831 A US 53856831A US 2028653 A US2028653 A US 2028653A
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Prior art keywords
relays
circuit
relay
section
conductors
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Expired - Lifetime
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US538568A
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English (en)
Inventor
Ekman Olof Ingemar Harald
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Telefonaktiebolaget LM Ericsson AB
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Telefonaktiebolaget LM Ericsson AB
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch

Definitions

  • the present invention has for its object to bring about a simple and inexpensive but nevertheless reliable automatic fire alarm system with two or more conductors in the loops containing the thermostats and is substantially characterized by that the conductors in each individual loop are permanently connected in parallel whereas the difierent loops are connected in series with each other and connected to a relay means which is common to all the loops and adapted to selectively indicate an interruption in a loop conductor or a short circuit between the loop conductors and to produce an alarm signal only upon an interruption in all of said conductors occurring, the loops being also provided with a section indicating device adapted to mark the loop in which an interruption in a single conductor or an interruption in all conductors has occurred.
  • Figure 1 is a circuit diagram for an automatic fire alarm plant according to the invention with section relays (double wound) common to the twoloop conductors in a loop for marking the section or loop in which an interruption or a short circuit has occurred.
  • Figure 2 shows another embodiment with separate section relays which at the same time serve as auxiliary relays for producing a fire alarm signal.
  • Figure 3 shows a modification of the arrangement according to Figure 1 with normally disconnected section relays which are connected into circuit with time lag and also serve as auxiliary relays for producing fire alarm signals.
  • I and II designate two series-connected loops or sections each consisting of two permanently parallel-connected conductors a, b, said loops or sections including a plurality 01' double thermostats T adapted to fuse in the event of a fire and to then simultaneously bring about an interruption in the loop conductors w, I).
  • Said loops are in known manner extending through the localities to be protected against fire whereas the portion of the plant indicated under the horizontal dot and dash line is disposed on a central switch board in the building. Only two loops are shown but several loops may be connected in series in an analogous manner.
  • the central battery which on account of the small current consumption in a plant according to the invention may consist of a dry battery, whereas in hitherto known plants it has been necessary to use storage batteries with expensive charging devices on account of the high closed circuit current consumption.
  • the parallel conductors a and b are included in a main circuit which in each of the parallel branches formed by said conductors includes a control relay and a resistance.
  • a low resistance Ma and a control relay Ra having a high resistance are included in the a-conductor whereas a high resistance Mb and a control relay Rb are included in the b-conductor.
  • Rh are normally passed by closed circuit current, then holding their contacts broken, whereas upon an interruption occurring in the corresponding loop conductor the appertaining control relay is de-energized, then closing its contacts.
  • the section relays SR1, SRu are the section relays SR1, SRu, each of said relays being provided with two windings on a common iron core and a common contact.
  • the coils designated a: and 0.11 are shunted between the ends of the a-conductors in the loops I and II respectively whereas the coils in and bu are shunted to the corresponding bconductor.
  • each of the windings an, in, bn When passed by current each of the windings an, an, in, bn produces a magnet field suificiently strong to alone attract the corresponding armature, and the two windings on a certain relay, by way of example in, b; of the re lay SR1, are wound in such a way that they cooperate when simultaneously passed by current.
  • BRR is an alarm-box control relay which is normally energized by the closed circuit current and serves to indicate that the circuit for the electric release of the alarm-box magnet BM is not broken and that the clock-work in the alarmbox is wound. up, a mechanically controlled contact kg in the alarm-box being opened when said clock-work is run down.
  • FR is a fault relay common to the Whole system which relay when energized in known manner connects a bell or an optical fault signalling device (not shown) into circuit.
  • the described arrangement operates in the following manner. Upon an interruption occurring in only one loop conductor, say the a-conductor of the loop I, the corresponding control relay Ra is de-energized at the normally closed circuit from the minus pole of the battery through the relay Ra the loops a of section I and II resistance Ma plus pole of the battery is broken, and releases its armature whereby its contact K4 is closed. This has, however, no effect on the alarm-box magnet BM as the circuit for said magnet is broken at the contact 702 of the other control relay Rb connected in series with the contact k1.
  • Each of the control relays R9. and Rh is provided with a contact k4 which short-circuits the relay winding when the relay drops its armature whereby the current through the windings of the section relays SR: and SR1: becomes stronger than otherwise would be the case.
  • both control relays Ra which is normally energized over the abovementioned circuit
  • Rb which is normally energized over a circuit from the minus pole of the battery through resistance Mb over conductor b in sections I and II, winding of relay Rb to plus pole of the battery, drop their armatures, the contacts 761 and k2 being then simultaneously closed and the battery B connected directly to the alarm-box magnet releasing the same so that an alarm signal is produced.
  • the said circuit is traced as follows: From the minus pole of the battery over contact K1 of the relay Ra, over contact K2 of the relay Rb, over contact K3 of the alarm box magnet, through the winding of said magnet to the plus pole of the battery.
  • the battery is connected to the alarm-box magnet BM over the alarm-box control relay BRR having a high resistance, but the weak closed circuit current then occurring is not suificiently strong to release the magnet BM.
  • the contacts In and k2 are closed said relay BRR is shunted whereby full current strength is obtained through the alarm-box magnet BM, which is then released as mentioned above.
  • both windings (11, hr of the section relay SR will become energized and co-operate to attract the armature of the relay whereby the section lamp SL1 is lit indicating that the release of the alarm magnet has been caused by an interruption insaid section.
  • control relay Ra If a short-circuit should occur between the aand b-conductors of a loop the control relay Ra will still remain energized for the reason that it is connected in parallel with the high resistance Mb so that a sufficiently high voltage drop exists between the ends of the winding of said relay.
  • the control relay Rb which is parallel-connected with the low-ohmic current limiting resistance Ma, will, on the other hand, be de-energized, its contact k5 being then closed causing a current to pass through the fault relay FR over a circuit from the minus pole of the battery through the winding of the relay FR, the low ohmicresistance r, the contact K5 of the relay Rb to the plus pole of the battery.
  • the relay FR attracts its armature and marks the fault.
  • the section relays SR1 and SR1: which, as already mentioned, upon an interruption occurring are series connected with the control relays Ra and Rh should have high resistances as compared with the resistances of the latter relays in order considerably to reduce the voltages on the same so that the relays RB. and Rb positively drop their armatures and remain with their armatures released.
  • the arrangement shown in Figure 2 differs from the one shown in Figure 1 partially therein that the section relays are divided on two relays SRra, SRIb and sRIIa, sRIIb respectively corresponding to the four simple windings 11.1, In, an, bn in Figure 1.
  • double fault relays FRa and FRb each having a group of signal lamps SL9. and SL1) are provided, one group for the a-conductors and one for the b-conductors.
  • the section relays are also provided with extra contacts k7 and k8 which are series-connected within each couple of relays SRm, SRrb and SRIIa, sR-IIb respectively appertaining to a section.
  • the relays Re and Rb are each provided with an extra contact 769 adapted to close the current through the appertaining fault relay m or FRb respectively when the control relay drops its armature (upon a. single or a double line interruption or a short circuit occurring).
  • Each of said fault relays FRa and FRb is provided with a contact km for closing the circuit of a fault indicating device indicated on the drawing as a bell KL, and also with an extra contact 761a, km. or krb, knb respectively for each section.
  • Each of the last mentioned contacts is included in the circuit of the corresponding section relay SRIa, sRIIa etc. having the same index. All section relays are thus normally disconnected and are connected into circuit first after a corresponding control relay Ra o'r Rb has been deenergized and has connected the appertaining fault relay FRE or FRb into circuit, at the con tacts 701a, krb etc. of which relay the circuits for the section relays are then closed.
  • the section relays are as already mentioned provided with contacts ks for lighting the signalling lamps SL@ and SLb and also with series-connected contacts 757 and k8 for auxiliary release of the alarm-box magnet BM in case the contacts 101 and k2 should fail, for instance not be clean or stick.
  • the plant according to Figure 2 operates safely also in case a short-circuit in the windings of the section relays should occur.
  • the loops are normally included in lines which only contain the control relays Ba and Rb, the battery B and the resistances Ma and Mb but no other relay windings or resistances, which ensures that a closed circuit current strength the control relays Ra, Rb will actually be broken upon an interruption in a loop conductor occurring and not maintained over any path of leakage.
  • the control relays Ra and Rb thereupon connect the fault relays PBS. and FRb into circuit while simultaneously releasing the alarm-box magnet BM in case a double interruption has occurred, the fault relay FRb and FRb finally connecting the section relays SRIb, SRIb etc. into circuit.
  • the plant according to the invention may also in known manner be provided with relays for indicating earthing of the loop conductors.
  • the resistance Ma may, for instance, be entirely dispensed with or substituted by a relay having a low resistance which relay is energized upon a short-circuit and is provided with a separate short-circuit indicating device, by way of example an optical device.
  • the relay Rb is then made with a higher resistance so that it does not drop its armature upon a short circuit occurring.
  • the simple control relays Rb and Rb may each be substituted by two or more seriesconnected relays in order to increase the safety of operation, as in this case at least any of the series-connected relays must drop its armature upon an interruption occurring in the loop conductors.
  • the short-circuiting contact K4 of the control relay Rb shown in Figures 1 and 2 may also be adapted to short-circuit the resistance Mb as well as the own winding of the relay when the relay drops its armature in order to reduce the resistance in the circuits for the section relays and, if desired, for the fault relays in case said relays are connected in series with the section relays (compare Figure l).
  • the series-connected normally open contacts 701 and kg of the control relays Ra and Rb may be substituted by parallel-connected normally closed contacts for opening the circuit of a special alarm relay controlled by closed circuit current which relay in turn, upon a simultaneous opening of said two parallel contacts, closes the circuit through the alarm-box magnet BM in order to release the same. Also the remaining normally open contacts may in similar manner be exchanged against normally closed contacts for closed circuit currents without considerably altering the rest of the plant.
  • a protective circuit including a plurality of loops each made up of two adjacent parallelly extending conductora the corresponding conductors of all loops being connected in series so as to form two circuit branches connected in parallel to a common source of current, thermostatic circuit breakers inserted in both conductors of each loop, a first electromagnet coil in one of said circuit branches, a second electromagnet coil in the other of said branches, an alarm, contact means and connections controlled by said electro-magnet coils, jointly, for closing a circuit through the alarm on the de-energization of both conductors, indicating means individual to each loop including two windings, each normally shortcircuited by one loop conductor, an indicator for each loop and connections and contact means controlled by said windings to close a circuit through a corresponding indicator, on a break in any loop.
  • a protective circuit including a plurality of loops each made up of two adjacent parallelly extending conductors, the corresponding conductors of all loops being connected in series so as to form two circuit branches connected in parallel to a common source of current, thermostatic circuit breakers inserted in both conductors of each loop, two relays allotted to each loop, a winding on each relay normally short-circuited by thecorresponding loop conductor, an alarm contact means and connections controlled by said relays jointly for closing a circuit through the alarm on a break in the loop, an indicator for each loop, and
  • a protective circuit including a plurality of loops each made up of two adjacent parallelly extending conductors, the corresponding conductors of all loops being connected in series so as to form two circuit branches connected in parallel to a common source of current, thermostatic circuit breakers inserted in both conductors of each loop, a first electromagnet coil inserted in one circuit branch at the positive pole of the current source, a resistance inserted in the same circuit branch, at the negative pole of the current source, a

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  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire Alarms (AREA)
US538568A 1930-05-07 1931-05-19 Fire alarm system Expired - Lifetime US2028653A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE2028653X 1930-05-07

Publications (1)

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US2028653A true US2028653A (en) 1936-01-21

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US538568A Expired - Lifetime US2028653A (en) 1930-05-07 1931-05-19 Fire alarm system

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US (1) US2028653A (pt)
BE (1) BE379643A (pt)
DE (1) DE592529C (pt)
FR (1) FR716742A (pt)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2724105A (en) * 1952-05-28 1955-11-15 Ekman Olof Ingemar Harald Electric control or alarm systems
US2946989A (en) * 1954-10-18 1960-07-26 Honeywell Regulator Co Temperature indicator and fire alarm system
US3044050A (en) * 1959-08-17 1962-07-10 Mc Graw Edison Co Fire detection system
US5172099A (en) * 1990-05-15 1992-12-15 Walter Kidde Aerospace Inc. Self monitoring fire detection system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2448716A1 (fr) * 1979-02-08 1980-09-05 Spie Batignolles Systeme pour detecter la rupture effective des ouvrages d'art

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2724105A (en) * 1952-05-28 1955-11-15 Ekman Olof Ingemar Harald Electric control or alarm systems
US2946989A (en) * 1954-10-18 1960-07-26 Honeywell Regulator Co Temperature indicator and fire alarm system
US3044050A (en) * 1959-08-17 1962-07-10 Mc Graw Edison Co Fire detection system
US5172099A (en) * 1990-05-15 1992-12-15 Walter Kidde Aerospace Inc. Self monitoring fire detection system

Also Published As

Publication number Publication date
BE379643A (pt)
FR716742A (fr) 1931-12-26
DE592529C (de) 1934-02-16

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