US2294043A - Automatic alarm system - Google Patents

Automatic alarm system Download PDF

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Publication number
US2294043A
US2294043A US184892A US18489238A US2294043A US 2294043 A US2294043 A US 2294043A US 184892 A US184892 A US 184892A US 18489238 A US18489238 A US 18489238A US 2294043 A US2294043 A US 2294043A
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United States
Prior art keywords
section
wires
current
alarm
sections
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Expired - Lifetime
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US184892A
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English (en)
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Nicou Hans Teodor
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Individual
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
    • G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
    • G08B25/018—Sensor coding by detecting magnitude of an electrical parameter, e.g. resistance
    • 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

  • This invention refers to automatic alarm systems having one or more control circuits, sections or loops connected to a source of current, such as a battery, and normally closed, each section being. provided with means, such as circuitbreakers, for breaking the circuit in case of fire or other danger.
  • circuit-breakers are arranged in the localities to be watched over through which said section or sections are drawn.
  • the chief object vof this invention is tocreate an automatic alarm system which may be built and operated at low costs but nevertheless is safe in operation and very reliable.
  • Another object of this invention is to simplify the construction of electric alarm systems, without reducing their reliability and safety of operation. In particular, the raising of alarm shall be secured also under unfavourable conditions.
  • Another object of this invention is torender it possible to increase the number of circuitbreakers, thermo-contacts or fuses to be used in each section, while still retaining a high selectivity and rendering it easytolocalize a fault or a fire.
  • Another object of this invention is to render it possible to localize the position of a fault or a danger, such as a fire, more accurately and more rapidly than heretofore.
  • Another object of this invention is to give an automatic and reliable indication of the position of a fault or a danger, by simple and inexpensive means.
  • Another object of this invention is to reduce the length of the wires necessary for the control circuits or sections, without reducing the reliability and the safety. Thus, the system will be less expensive and also less exposed to line faults and fault signals.
  • Fig. 1 shows an electric alarm system in accordance with this invention.
  • Fig. 2- shows a modification.
  • Fig. 1 of the drawings indicate two control circuits, sections or loops drawn through the localities to be watched over. It is understood that the number of sections is arbitrary, though only two sections are shown for the sake of clearness. In'some-cases one single section may be used. Each section comprises two conductors or wires 11, b and a number of circuit-breakers, thermo-contacts or fuses T, it
  • the branch or wire I) of section I has one end connected with the+ pole-of a central battery B via the winding .of a section relay Rb and the normally closed contact bv of that *relaywhich is normally energized like all the section relays.
  • the other end of that wire is connected with an inner point of the battery B at the'tapi Ill-via the normally closed contact-19h of the'relay Rb.
  • To that same tap l 0 one end of the wire a of section I is connected via the windingqof section relay R9. and the normally closed contact an of that relay.
  • the opposite end of the same wire a is connected with the pole of the-battery B via the normally closed contact av of the relay Ra and the small protective resistance m.
  • the contacts av, ah, bv, bh are double, the-upper contact of each pair being normally closed while the lower one is normally open.
  • Two milliamperemeters 'Av, Ah are provided, each connected in series with a battery B1 and'Bz. These amperemeters are connected with the normally open contacts of the'pairs av, ah, bv, bh.
  • the right-hand ammeter Ah is connected with one such contact at bh andanother at an of the relays Ra, Rb of section I and also with the same contacts of the relays Rm, RIIb of section II etc.
  • the left-hand ammeter Av is connected with the normally open contacts av, bv'of the sections. Taps for connecting further sections to the ammeters are shown at 8.
  • the milliamperemeters Av, Ah are common to all'sections, while each section has its individual section relays Ra, Rb, RIIa,RIIb.
  • thermocontacts or fuses Two preferred embodiments of thermocontacts or fuses are shown in detail and on a larger scale in section I.
  • the contact springs 3, 4 are soldered together by means of a low-melting soldering metal-in such manner that these springs will spring apart When-the solder melts as a result of a temperature higher than that permissible in the locality to be controlled in which the thermocontact 'is placed. By these means a reliable breaking of the contacts 3, 4 is secured, when the solder fuses. When the springs 3, 4 thus spring outwards they make contact with contact pieces or wires 5, 6
  • thermocontact T a contact between the wires a, b and a contact between wires a, b of different signs on both sides of the break. Because the pieces 5, 6 both have the same function, there is double safety for really effecting a contact between the Wires (1, b.
  • thermocontact T of section I diifers from the thermocontact just described substantially in this that one single contact piece or cross-conductor 1 is arranged on each side of the contact springs 3, 4.
  • the conductor 1 may consist of a simple metallic cross-piece secured to a pillar or plinth, around which the base plate of the thermocontact is cast or pressed.
  • the section relays Ra, Rb, RIIa, Bill) also have normally closed contacts kv, kn.
  • the contacts kin of relays Ra, Rm. and those of the section relays of wires a of additional sections, if any, are connected in series in a circuit from the pole of battery B1 through of contacts kh, conductor I00, winding of normally energized alarm relay ARB- back to the pole of B.
  • a similar circuit extends from the pole of battery B, through all the contacts lav in series, conductor 10!, winding of normally energized relay ARb to the pole of B.
  • a normally open alarm circuit extends from pole of battery B via normally open contacts of relay ARb, conductor I03, fire alarm BS, conductor I02, contacts of relay ARa back to pole of B. The circuit is not closed until both alarm relays ARa, ARb fall ofi simultaneously and close their contacts.
  • thermocontact broken (indicated by a broken line), across to the wire b, back through righthand part of wire b, lower contact at an, amperemeter Ah to pole of B2.
  • the two amperemeters are automatical- 1y connected with that section, say I, which has been broken and now measure the intensities of the currents through the wires of different signs (a, b) connected together, on both sides of the thermocontact broken. It is evident that these amperemeters, if properly graduated, directly indicate the position of the break, for instance, by means of a code number or other mark. There are two circuits (1) and (2) above for indicating the break, giving double security. If, as a result of bad contacts at the springs 3, 4 of the thermocontact fused, the two amperemeters show different indications, the amperemeter giving the highest indication or deviation should be followed.
  • the amperemeters should, preferably, be graduated in opposite directions. By suitable reversion they may, of course, be graduated in the same direction.
  • the needles of the amperemeters may also be arranged co-axially on the same dial so that the needles register both normally and after a section has been broken. In case of difference, it is then easier to see which needle has the greatest deviation. It is to be observed that a greater difierence between the deviations of the amperemeters indicates that several thermocontacts are broken. Consequently, the amperemeters indicate the limits of the spread of the fire.
  • the relays Ra, Rb, Rm, RIIb in the normal manner indicate the sections in which a fault has occurred or from which alarm is given.
  • the sections may be made far greater than heretofore, without any inconveniences, because the milliamperemeters which are automatically cut in in case of alarm, directly localize and indicate that thermocontact which has been broken.
  • the number of thermocontacts of a section may be increased to or more. This is very advantageous. Because it is necessary to draw wires back to the central post say for each group of 100 thermocontacts only, the total length of wire required is reduced, while simultaneously the indication is far more precise than in the systems heretofore known.
  • condensers 9. are inserted. between.the wires a, b, one. condenser, being providedat each thermo-, contact.
  • the condenser may be. placed on. either sideof the thermocontact.
  • the con-. denser is inserted into a recess of the base plate of ,the thermocontact, is soldered to the. termi-L nals of the thermocontact and coated with a suitable solidifying mass, protecting. thecon-. denser against moistureetc.
  • a source of alternating or pulsatory current is provided in the central postfor the milliamperemeters- In Fig. v2;.said sourceis illustrated as current-breaking buzzers S sending a pulsating current through ,themilliamperemeters Av, Av, when the relays. .ofya. section, say Ra, Rb, are. released. simultaneously.
  • an inductor or a relay device or a mechanically driven switch which alternately charges and discharges a central condenser battery, may be substituted.
  • thermocontacts or fuses which only are broken in case of fire but do not interconnect the wires a, b on both sides of the break.
  • the plant shown in Fig. 2 is similar to that shown in Fig. 1 and corresponding parts carry the same reference characters. Also the operation is quitesimilar.
  • thermocontact When a thermocontact is broken in the sys-. tem shown in Fig. 2, the amperemeters and their sources B1, S; B2, S of alternating orpulsating current-are automatically connected with the section, say I, containing that thermocontact.
  • the lefthand amperemeter Av is connected with those parts of the wires a, b which are to the left of the broken contact T (indicated by abroken line).
  • the right-hand amperemeter Ah is connected with those parts of the same wires which are to the right of the broken contact.
  • thermocontactin For each unbroken thermocontactin theseleit and right parts a condenser 9 is inserted between the wires'a, b and lets through a partial or shunt current between them. If the'condensers 9 are of approximately the same size and the ohmic resistance of the wires may be neglected, this being quite permissible if the wires are properly dimensioned, the amperemeters directly indicate the position of the broken thermocontact, because the intensity of the current is substantially proportional to the number of condensers in the left or right parts, respectively, and consequently to the number of thermocoutacts between the measuring instrument Av, Ah and the break.
  • the giving of alarm is quite independent of the condensers 9 and the instruments Av, An.
  • a break or a short-circuit in a condenser does neither put the system out of operation nor prevent alarm from being raised properly.
  • a break in a condenser only has the effect that in case of alarm the thermocontact next to that actually broken is indicated as broken, that is: the break only causes an indication incorrect by a single step.
  • a short-circuit within a condenser 9 is immediately indicated by one of the section relays as an ordinary shortcircuit or leakage between the wires, for instance, as described in U. S. Patent No. 2,059,510 or the U. S. patent application Serial No. 184,100 referred to above.
  • thermocontactT thermocontact
  • thermocontact only every second or fifth thermocontact has;
  • thermocontacts are; of the ordinary design without any condensers or cross-contacts.
  • the condensers may have graded sizes dependingupon their distance from. the central post, to compensate for the ohmic resistance of the wires 0,, b.
  • thermocontacts of .a whole plant may be included in one single section, indication by means of milliamperemeters being pro.- vided say for every twentieth or thirtieth thermocontact.
  • Such system has a very low cost of construction and is in many cases sufficient.
  • asuitable kellog-switch or the like is provided for each section.
  • that section is disconnected from the other by use of said switches and is connected with a special alarm relay common to all sections, while the remaining sections are still connected in series.
  • the amperemeters will first indicate the section in which a break occurs. After that section has been disconnected from the oth rs and is alone connected with the ampererneters, the latter will indicate the position of the broken thermocontact within the section.
  • selectors or finders may be used for connecting the amperemeters to the alarm-giving section.
  • This invention may also be applied to plants having one or more single wire sections, the earth serving as a return path for the current.
  • parts of the central battery B may be used instead of the batteries B1, B2. Only one milliamperemeter may be used but two milliamperemeters give a double control and also an indication of the extension of the fire.
  • this invention may very advantageously be applied to ships and other structures comprising a great number of small localities to be controlled.
  • the high localizing capacity of this system is of special importance, because the systems heretofore known cannot efiect such localizing of high ex-.
  • an automatic electric alarm system in combination, a loop of insulated wires normally closed extending through the locality to be watched over, current-breakers in said wires responsive to the cause of danger to be warned against, condensers connected at intervals be tween said wires, a source of current connected to said wires to deliver current to them, as long as they are unbroken, said current being of a character to which said condensers set a high resistance, a second source of current of sulficiently high frequency that said condensers set a comparatively low resistance to the flow of it, means for electrically measuring the current from said second source, when connected to one end of said loop, after one of said current-breakers is opened, and an electric alarm mechanism connected to said wires to raise alarm, when one of said current-breakers is opened.
  • an automatic electric alarm system in combination, a battery for direct current, a loop of insulated wires normally causing direct supervisory current and connected to said battery and extending through the locality to be watched over, current-breakers in said wires responsive to the cause of danger to be warned against, condensers connected in parallel between said wires at intervals between said current-breakers, a source of pulsatory current for cooperating with one end of said loop, said pulsatory current having sufiiciently high frequency that even one of said condensers sets a comparatively low resistance to said pulsatory current, means for measuring said pulsatory current passing through one or more of said condensers, when one of said ourrent-breakers has been opened, and an electric alarm mechanism connected to said wires to raise alarm, when one of said current-breakers is opened.
  • an automatic electric alarm system in combination, a loop of insulated wires normally closed and extending through the locality to be watched over, current-breakers in said wires responsive to the cause of danger to be warned against, condensers connected in parallel at intervals between said wires, a source of current connected to said wires to pass current normally through said wires as long as they are unbroken, the current delivered by said source being of such character that it is substantially incapable of passing through said condensers, normally closed section relays in said wires, an alarm apparatus connected with said relays to raise alarm, when one of said current-breakers is opened and releases said relays, a second source pulsatory current connected with said relays to be connected with one end of said loop when said relays are released, the current delivered by said second source of current being of sufiiciently high frequency that it is capable of passing easily through one or more of said condensers, and means associated with said second source of current for measuring the pulsatory current when said relays are released.

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  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Emergency Alarm Devices (AREA)
US184892A 1937-01-20 1938-01-13 Automatic alarm system Expired - Lifetime US2294043A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE202679X 1937-01-20

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US2294043A true US2294043A (en) 1942-08-25

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US184892A Expired - Lifetime US2294043A (en) 1937-01-20 1938-01-13 Automatic alarm system

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US (1) US2294043A (fr)
BE (1) BE425857A (fr)
CH (1) CH202679A (fr)
DE (1) DE722085C (fr)
FR (1) FR832277A (fr)
NL (1) NL54631C (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2636163A (en) * 1951-04-19 1953-04-21 Earle V Gardiner Burglar alarm system
US2696603A (en) * 1952-06-10 1954-12-07 Ekman Olof Ingemar Harald Two-wire alarm or control system
US3648268A (en) * 1969-11-03 1972-03-07 Melvin Paull Surveillance and alarm system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1075019B (de) * 1960-02-04 Dragerwerk Hemr S. Bernh Drager Lübeck Elektrischer Fern Temperatur-Anzeiger fur Kraftfahrzeuge

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2636163A (en) * 1951-04-19 1953-04-21 Earle V Gardiner Burglar alarm system
US2696603A (en) * 1952-06-10 1954-12-07 Ekman Olof Ingemar Harald Two-wire alarm or control system
US3648268A (en) * 1969-11-03 1972-03-07 Melvin Paull Surveillance and alarm system

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Publication number Publication date
BE425857A (fr)
NL54631C (fr)
FR832277A (fr) 1938-09-23
DE722085C (de) 1942-06-30
CH202679A (de) 1939-01-31

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