US3857061A - Safety circuit for the detection of the simultaneous actuation of two antagonizing units - Google Patents

Safety circuit for the detection of the simultaneous actuation of two antagonizing units Download PDF

Info

Publication number
US3857061A
US3857061A US00414377A US41437773A US3857061A US 3857061 A US3857061 A US 3857061A US 00414377 A US00414377 A US 00414377A US 41437773 A US41437773 A US 41437773A US 3857061 A US3857061 A US 3857061A
Authority
US
United States
Prior art keywords
supply
circuit
antagonizing
units
amplifier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00414377A
Other languages
English (en)
Inventor
R Boudault
C Guion
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Philips Corp
Original Assignee
US Philips Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3857061A publication Critical patent/US3857061A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/097—Supervising of traffic control systems, e.g. by giving an alarm if two crossing streets have green light simultaneously

Definitions

  • ABSTRACT I A safety circuit which is provided with two separate amplification channels, each of which comprises two cascade-connected amplifiers. An approval signal is applied to a common input, and an approval signal can be derived from a common output if the units to be supervised function properly.
  • the invention relates to a safety circuit for the detection of the simultaneous actuation of two antagonizing units, each of which is supplied with an alternating voltage via a static switch, the said circuit supplying an approval signal if no supply voltage is simultaneously applied to the two antagonizing units.
  • Antagonizing units are to be understood to means herein units which for reasons of safety may never be simultaneously active.
  • these units may be the green traffic lights which control the access of vehicles to two intersecting roads, in which case the simultaneous lighting up of the two lights constitutes a major danger.
  • For controlling traffic lights use is increasingly made of static power switches of the Triac type which are controlled by signals originating from a control logic.
  • the safety circuit has for its object to detect dangerous situations of this kind and to supply an approval signal if no voltage is simultaneously applied to the two lights, and to suppress this signal in the opposite case.
  • this circuit must be designed such that, no matter what faults occur in its connections and/or components, the approval signal is definitely suppressed if the status of the switches gives rise to a dangerous situation.
  • the invention has for its object to provide a new structure for a safety circuit of this kind for use when the antagonizing lights (and more in general two antagonizing units) are supplied via static switches.
  • a safety circuit of this kind comprises two amplification channels which receive an approval signal of a given frequency, the outputs thereof being coupled to the output of the safety circuit, each amplification channel comprising a cascade-connection of two amplifiers, the direct current supply for these two amplification channels being provided for one of the amplification channels by a pair of supply circuits which are each connected to the terminals of the switch which controls one of the antagonizing units, and for the other amplification channel by another pair of supply circuits, each of which is connected to the terminals of the switch which controls the other unit, both supply circuits of each pair comprising a rectifier which is arranged in one supply circuit so as to rectify the positive half-cycles of the alternating voltage and in the other supply circuit so as to rectify the negative half-cycles, these two supply circuits supplying the one and the other amplifier of the amplification channel, respectively.
  • FIG. 1 shows the diagram of a safety circuit according to the invention.
  • FIG. 2 is a table showing the various states of the traffic lights and the switches.
  • the safety circuit is used for the detection of the simultaneous lighting up of two antagonizing green traffic lights at an intersection. These two lights L, and L are supplied by the alternating voltage between the supply lines 1 and 2 via the switches 8,, S (Triacs). The terminals 3, 4 of the switches 8,, S are connected to line 1 via the lights L, and L The terminals 5 and 6 are connected to line 2.
  • switches 8,, S Triacs
  • the terminals 3, 4 of the switches 8,, S are connected to line 1 via the lights L, and L
  • the terminals 5 and 6 are connected to line 2.
  • the switches are Triacs, which means a switch which is made of semiconductor material in which pn-junctions are provided, the said switch being active for both positive and negative voltages and being controllable at a control terminal.
  • the switches 8,, S have control ter minals 7, 8 which are connected to the logic unit 9 which controls the traffic lights.
  • logic unit 9 In the case of normal operation, logic unit 9 never supplies signals which cause the simultaneous lighting up of the two lights L, and L However, the latter situation may arise if given faults occur in the logic unit. Faults can also occur in the switches 5,, S These faults (short-circuit or interruption) can occur in the one as well as in the other pn-junction or in both junctions at the same time. In the case of faults in the logic unit or in the switch, both lights L, and L can light up simultaneously, a light being supplied by the positive halfcycles or the negative half-cycles of the alternating voltage or by both. In any case, the simultaneous lighting up of the two lights L, and L is considered danger ous. Y
  • the safety circuit detects all combinations of states of the switches S, and S which give rise to a dangerous situation. Between its two output terminals 10 and 11 the safety circuit supplies an approval signal for the status combinations which do not give rise to a dangerous situation, and it suppresses this signal for a dangerous situation. I i
  • the table of FIG. 2 illustrates all status combinations of the switches S, and S In the first column the possible status combinations are numbered from 1 to 16.
  • the second and the third column relate to switch 8,.
  • Column A relates to the pn-junction which can be conducting during the positive half cycles of the alternating voltage
  • the column A relates to the pn-junction which can be conducting during the negative half-cycles.
  • the symbols 1 and 0 in these columns indicate that the relevant pnjunction is conducting or non-conducting, respectively.
  • the fourth and the fifth column A; and A indicate in the same manner for the switch S the states of the pn-junctions which can be conducting during the positive and the negative half-cycles, respectively.
  • the columns L, and L Show the states of the lights L,, L
  • the symbol 0 indicates that no voltage is applied to a light (extinguishing).
  • the symbol 1 indicates that a voltage is applied to a light (lighting up). No distinction is made between a voltage comprising positive and negative half-cycles and a voltage having only positive or only negative half-cycles.
  • the symbol 1 denotes a non-dangerous status combination for which the safety circuit must supply an approval signal
  • the symbol 0 denotes a dangerous status combination for which the safety circuit must suppress the approval signal.
  • the safety circuit must supply an approval signal (S l) for the status combinations 1, 2, 7 in which at least one of the two switches S and S is non-conducting for the positive and/or the negative half-cycles of the alternating voltage.
  • the approval signal must be suppressed (S for the status combinations 8, 9, 16 in which both switches are conducting.
  • the safety circuit shown in FIG. 1 comprises two amplification channels 12, 13, the input of which receives an approval signal of a given frequency, the said signal always being present between the terminals 14, 15.
  • the outputs of the two amplification channels 12, 13 are coupled to the output terminals 10, 11 of the safety circuit via the transformer 16.
  • the latter comprises two primary windings 17 and 18 which are connected to the output of the amplification channels 12 and 13, respectively, and a secondary winding 19 which is connected to the terminals 10, 11.
  • Each amplification channel 12, 13 comprises two amplifiers 20 and 21, 22 and 23, respectively, which are cascade-connected and which are coupled via a transformer 24, 25.
  • the direct current supply for the amplification channel 12 is provided by the supply circuits 26, 27, the inputs of which are connected parallel to the terminals 3, of the switch 8, (directly for the terminal 3, and by way of the resistor 28, 29 for the terminal 5).
  • the direct current supply for the amplification channel 13 is provided by the supply circuits 30, 31, the inputs of which are connected parallel to the terminals'4, 6 of the switch S (directly for the terminal 4, and by way of the resistor 28, 29, for the terminal 6).
  • Each of the supply circuits 26, 27 comprises a rectifier 32, 33, respectively.
  • the rectifier 32 of the circuit 26 is connected so as to rectify the positive half-cycles of the alternating voltage
  • the rectifier 33 of the circuit 27 is connected so as to rectify the negative halfcycles.
  • Each ofthe supply circuits 30, 31 comprises a rectifier 34, 35, respectively.
  • the rectifier 34 of the circuit 30 is connected so as to rectify the positive halfcycles of the alternating voltage, and the rectifier 35 of the circuit 31 is connected was to rectify the negative half-cycles.
  • the rectifiers 32, 33, 34, 35, respectively are connected to a smoothing circuit which consists of the parallel connection of a Zener diode 36, 37, 38, 39 and a capacitor 40, 41, 42, 43, respectively.
  • the direct voltages which are obtained on the outputs of the supply circuits 26, 27 are applied to the input terminals of the amplifier 20, 21, respectively, of the amplification channel 12.
  • the direct voltages obtained on the outputs of the supply circuits 30, 31 are applied to the input terminals of the amplifier 22, 23, respectively, of the amplification channel 13.
  • the'supply circuits 26, 27, 30 and 31 perform the function of detectors of the status of the switches S, and S
  • the two amplification channels 12 and 13 perform the function of a logic circuit which allows passage of the approval signal or blocks this signal in accordance with the table of FIG. 2.
  • the supply circuit 26 applies a supply voltage to the amplifier only if an alternating voltage containing positive half-cycles is present on the input,
  • the supply circuit 27 applies a supply voltage to the amplifier 21 only when the switch S is not conducting during the negative half-cycles.
  • the supply circuits and 31 apply a supply voltage to the amplifier 22, 23 only if the switch S is not conducting during the positive or negative halfcycles, respectively, of the alternating voltage.
  • both switches S and S are conducting during at least one of the two half-cycles of the alternating voltage, with the result that at least one of the amplifiers of the two amplification channels 12 and 13 receives no supply voltage. In this case the two amplification channels 12 and 13 are blocked, with the result that the approval signal is suppressed.
  • the safety circuit shown in FIG. 1 optimally satisfies the safety rule that faults in the connections or components can cause the suppression. of the approval signal, but in any case prevent that the suppression does not take place in one of the dangerous status combinations 8, 9, 16.
  • the component faults to be taken into consideration are a short-circuit or an interruption for the pn-junctions and the capacitors, and an interruption for the resistors and windings of the transformers.
  • the two amplification channels 12, 13 between the input l4, l5 and the output 10, 11 of the safety circuit are constructed in conformity with the said safety rule.
  • Each of the amplifiers can be constructed as shown in FIG. 1 for amplifier 20.
  • This amplifier comprises a transistor 44, the base of which is connected to the input terminal 15 by way of the resistor 45, its emitter being connected to the input terminal 14 and to'the supply terminal and its collector being connected to the supply terminal by way of the resistor 46 and the primary winding of the transformer 24.
  • the resistor 45 limits the current at the input of the amplifier 20, with the result that in the case of a fault in this transistor the approval signal is substantially not applied to the amplifier'21.
  • the resistor 46 limits the collector current of the transistor 44.
  • Connected between the terminals of the primary winding of the transformer 24 is the diode 47 in order to eliminate overvoltages which might damage the transistor 44.
  • a fault in one of the components of the amplifier 20 causes suppression of the approval signal in the amplification channel.
  • the approval signal on the output terminals 10, 1 1 is then immediately suppressed if the light:l. is on or will be interrupted as soon as the light L is switched on.
  • the supply circuits 26, 27 and 30, 31 are also constructed in conformity with the said safety rule.
  • the amplifier 20 In'the case of an interruption or a short-circuit of the rectifier 32 of the supply circuit 26 or a short-circuit of the capacitor 40 or of the Zener diode 36, the amplifier 20 is no longer supplied with a voltage and the approval signal is suppressed in the amplification channel 12.
  • the amplifier 20 In the case of interruption of the Zener diode 36 or of the capacitor 40, the amplifier 20 is not normally supplied and can possibly function, but in that case the supply circuit 26 continues to perform its function as detector of the status of switch S
  • the approval signal which is applied to the input of the safety circuit may be a sinusoidal alternating voltage, but can alternatively be a pulse-shaped signal.
  • the number of safety circuits equals the number of said pairs. It will then be advantageous from a safety point of view to connect these safety circuits in cascade so as to form one safety unit comprising one input and one output for the approval signal.
  • each amplifier comprises a transistor, the base of which is connected to an input terminal of the amplifier, its emitter being connected to the other input terminal of the amplifier and to a supply circuit output terminal, andits collector being connected to the other supply circuit output terminal by way of a primary winding of a coupling transformer.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Amplifiers (AREA)
  • Traffic Control Systems (AREA)
  • Train Traffic Observation, Control, And Security (AREA)
US00414377A 1972-11-15 1973-11-09 Safety circuit for the detection of the simultaneous actuation of two antagonizing units Expired - Lifetime US3857061A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7240508A FR2206609B1 (enrdf_load_stackoverflow) 1972-11-15 1972-11-15

Publications (1)

Publication Number Publication Date
US3857061A true US3857061A (en) 1974-12-24

Family

ID=9107196

Family Applications (1)

Application Number Title Priority Date Filing Date
US00414377A Expired - Lifetime US3857061A (en) 1972-11-15 1973-11-09 Safety circuit for the detection of the simultaneous actuation of two antagonizing units

Country Status (4)

Country Link
US (1) US3857061A (enrdf_load_stackoverflow)
DE (1) DE2353969A1 (enrdf_load_stackoverflow)
FR (1) FR2206609B1 (enrdf_load_stackoverflow)
GB (1) GB1409213A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4835534A (en) * 1985-09-05 1989-05-30 U.S. Philips Corp. Monitoring a conflict detector for traffic-lights

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3107090A1 (de) * 1981-02-25 1982-09-09 Siemens AG, 1000 Berlin und 8000 München Verfahren und schaltungsanordnung zur ueberwachung wechselstromgespeister verkehrssignalanlagen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3355601A (en) * 1965-10-22 1967-11-28 Franz Baumgartner Fabrik Elek Supervisory control system using a ferrite transformer and a transistor
US3457430A (en) * 1966-12-07 1969-07-22 Bliss Co Anticoincidence load control circuit

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1285396A (fr) * 1961-01-12 1962-02-23 Westinghouse Electric Corp Perfectionnement apporté aux circuits de déclenchement destinés à protéger des interrupteurs à semi-conducteur
DE1588410C3 (de) * 1967-02-01 1974-01-03 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Schaltungsanordnung zur fehlersicheren Überwachung des Schaltzustandes mindestens zweier Schaltstrecken
DE1613832B1 (de) * 1967-05-17 1971-01-07 Licentia Gmbh Schutzeinrichtung fuer Mehrfachantriebe

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3355601A (en) * 1965-10-22 1967-11-28 Franz Baumgartner Fabrik Elek Supervisory control system using a ferrite transformer and a transistor
US3457430A (en) * 1966-12-07 1969-07-22 Bliss Co Anticoincidence load control circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4835534A (en) * 1985-09-05 1989-05-30 U.S. Philips Corp. Monitoring a conflict detector for traffic-lights

Also Published As

Publication number Publication date
FR2206609B1 (enrdf_load_stackoverflow) 1975-11-07
DE2353969A1 (de) 1974-05-22
FR2206609A1 (enrdf_load_stackoverflow) 1974-06-07
GB1409213A (en) 1975-10-08

Similar Documents

Publication Publication Date Title
US3769571A (en) Power inverter circuit
US3363143A (en) Alternating current switching power contact with soft start and circuit protection
US3386027A (en) High voltage converter apparatus having a plurality of serially connected controllable semiconductor devices
US3711747A (en) Power transformer primary winding fuse arrangement
US3154695A (en) Gating control apparatus wherein static switches in the respective phase lines of a polyphase system are phase-sequence gated by a controlled gating signal
US3781637A (en) Inrush-current limiting device
US3401303A (en) Circuit closing and interrupting apparatus
GB915853A (en) Inverter network utilising controlled semi-conductor devices
US3651375A (en) Protective circuit for a thyristor type switch
US3801832A (en) Solid-state relay
JPS6070976A (ja) 加速電源装置
US3857061A (en) Safety circuit for the detection of the simultaneous actuation of two antagonizing units
US3308397A (en) Saturable current transformertransitor inverter circuit
US3588598A (en) Lighting-control systems
US3307171A (en) Apparatus for energizing an electrical load device
US4691263A (en) Low leakage, solid state a-c power contact
US4021683A (en) Electronic switching circuits
US3258704A (en) Signal si
US3254236A (en) Voltage sharing circuit
US2909705A (en) Control circuit
US3417315A (en) Static inverter
US3206695A (en) Overvoltage protection circuit for power converters
US2337918A (en) Electric valve circuits
US3110856A (en) Semiconductor fault detecting trip circuit
US3054003A (en) Electronic relay responsive to instantaneous polarity of control signal whether alternating current or direct current