US1991232A - Electrical system providing sequence operation - Google Patents

Description

Feb. 12, 1935. c. v 5. sun's ELECTRICAL SYSTEM PROVIDING SEQUENCE OPERATION Original Filed Aug. 30

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m W 8 m U 0 t H t w A n .s w H h C Patented Feb. 12, 1935 UNITED STATES PATENT OFFICE ELECTRICAL SYSTEM PROVIDING SEQUENCE OPERATION Chauncey G. Suits, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York 11 Claims.

My invention relates to electrical systems containing a plurality of units which operate in a definite sequence. More particularly it relates to an electrical system comprising a series of lamps which are operated successively either to become illuminated or extinguished in a predetermined sequence. My present invention is a further development of the system disclosed and claimed in my copending application, Serial No. 582,801, filed December 23, 1931, and assigned to the same assignee as my present application.

In that system of sequence operation of a plurality of units, the circuit of the last unit of a group comprising a series was connected back to control the circuit of the first unit of the series, whereby the units of the series were alternately energized and deenergized.

In certain cases, as for example in the operation of electric signs where the units are electric lamps, it is sometimes desirable that a greater time delay or a pause shall occur following the operation of the last unit of the series. A greater time delay also is desirable in cases where the series comprises so few units that the delay apparatus employed therein between units provides insufiicient time for the units, particularly where they are incandescent lamps, to completely respond to one condition before they are subjected to the opposite condition. For example, if the series comprises only four or five lamps the energization and deenergization of the lamps may succeed each other so rapidly that the filaments cannot fully respond thereto.

My present invention has for its object the provision of an improved system of the above described character whereby a greater time delay is effected between an operation of the last unit of the series and an opposite operation of the first unit of the series. A further object of my invention is the provision for such time delay without causing any noticeable fiicker in the units incident to the operation of the delay producing means.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Referring to the drawing Fig. l is a circuit diagram of one embodiment of my invention; Figs. 2 and 3 are fragmentary diagrams illustrating modifications of what is shown in Fig. 1; Fig. 4 is a curve illustrating the operation of the arrangement shown in Fig. 3; Fig. 5 shows a further modified form; and Figs. 6 and 7 illustrate two forms of saturable core reactor which may be used in the apparatus shown by Figs. 1, 2 and 3.

In the drawing an alternating current supply circuit is shown at 1 and 2 which may be connected with any suitable source of alternating current illustrated at 3, which for example may be a 110 volt, 60 cycle source. Connected across the supply circuit 1 and. 2 is a series of branch circuits, each containing a load device, such as an incandescent lamp, represented by 10 4, 5, 6 and 7. Such load devices may for example be beacon or field border lamps at an airport, the lamps of an electric sign or any other load devices which it is desired to have operate in a certain sequence. In each branch 15. circuit and in series with the load device of that circuit is the alternating current winding 9 of a saturable core reactor 10 having a direct current saturating winding 11. The winding 11 of each of these reactors is with the exception 20 of the reactor in the first branch circuit shown connected across the lamp of the preceding branch through a full wave rectifier, which may be of well known construction, represented at 12. In the first branch circuit of the series is 25 the starting switch 13. The rectifier 12 associated with the reactor of the first branch circuit has one terminal connected through a resistor with the supply line 1 and the other terminal connected through conductor 12' and the contacts 30 of the relay 14 with the supply line 2. The winding 15 of relay 14 is connected across the re actor 10 of the last branch circuit, whereby when the impedance of reactor 10 increases due to the desaturation of its core the relay is operated to 35 close its contacts l4 and conversely when the impedance of the reactor decreases due to the saturation of its core, the relay becomes deenergized sufficiently to allow the relay to move to open circuit position. Arranged in shunt with 40 the winding 15 of relay 14 is the capacitor 16 whoseca'pacitance has such a value that the impedance offered by the winding 15 and the capacitor 16 is the same whether the relay is in closed or open circuit position. Thus the ef- 45 feet of the armature of the relay in varying the inductance of winding 15 in response to its movement is completely compensated by the capacitor 16.

, The operation of this form of my invention is 50 as follows: Supposing the lamps 4, 5, 6 and '1 of the series are dark and closing of the switch 13 causes lamp 4 to be illuminated inasmuch as the reactor 10 in series therewith being saturated by winding 11 oflers a minimum impedance. The v lamps 5, 6 and 7 remain dark inasmuch as the reactor 10 in series with each being unsaturated offers a maximum impedance. As soon as current fiows through lamp 4 of the first branch, the potential drop across that lamp causes the reactor 10 of the second branch to become saturated whence the impedance oifered by that reactor drops to such a value that lamp 5 is illuminated. In a similar manner each lamp of the series successively becomes illuminated, the operation of each reactor producing a predetermined time delay so that the lamps become illuminated in a definite sequence. When lamp 7 of the last branch becomes illuminated due to the decrease in impedance of the reactor in series therewith, relay 14 drops open and thereby cuts of! the supply of saturating current to reactor 10 of the first branch of the series. The impedance of this reactor accordingly rises to such a value that lamp 4 is extinguished. In a similar manner each succeeding lamp of the series becomes extinguished. In addition to the time delay produced by the reactor 10 of the first branch circuit between the operation of lamp 7 and the lamp 4, the efiect of the relay 14 is to introduce an additional time delay, the amount of the delay being governed by the spacing of the contacts and the construction of the relay.

In certain cases I have found that the change in the magnetic circuit of the relay due to the operation thereof caused an undesirable flicker in the lamps. This however I am able to avoid by the use of the capacitor 16 in shunt with the winding of the relay, this capacitor as has been pointed out above having such a value that the total impedance offered by the relay winding and the capacitor is substantially the same whether the relay is in open or closed circuit position.

In the modified form of my invention illustrated by Fig. 2 the relay winding 15 is supplied by rectified current from the rectifier 17 connected across the reactor 10 of the last branch. With this arrangement I have found that it is unnecessary to provide a capacitor across the relay winding to avoid flicker of the lamps since the transient current which flows when the relay armature changes position is dissipated in the relay winding now in the rectifier circuit in such a manner that the alternating current impedance of the combination is substantially unaltered by the movement of the relay armature. The circuit otherwise is the same as in Fig. 1.

In the modified form illustrated by Fig. 3 the additional time delay between an operation of the lamp in the last branch circuit and an opposite operation of the lamp in the first branch circuit is eflected by the use of the resonant circuit 20 which has a non-linear volt-ampere characteristic. This circuit is shown including the reactor 21 and capacitor 22 connected in series and bridged across the reactor 10 of the last branch circuit. The rectifier 12 of the first branch circuit in this case is connected by conductor 12' with the non-linear resonant circuit between the reactor and the capacitor thereof. For the purpose of preventing a fiicker of the lamps due to the operation of the non-linear resonant circuit, I employ the capacitor 23 in shunt therewith. It is well known that when the voltage applied to a non-linear resonant circuit is gradually increased the circuit becomes resonant at a certain voltage and the current fiow in the circuit at this voltage suddenly rises and with further increase in voltage continues to rise at a less rapid rate, the point of sudden rise of voltage being known as the resonant voltage. It is also well known that if the applied voltage is gradually decreased a voltage will be reached at which the current suddenly decreases, which voltage is known as the dissonant voltage. This phenomenon is illustrated by way of example in Fig. 4 which shows the voltage-current curve of a nonlinear resonant circuit. In this figure, curve 25 represents the increase in current due to a gradual increasing applied voltage, and curve 26 represents the decrease in current due toa gradually decreasing applied voltage. It will be noted that the value of the voltage at which the current represented by 26 suddenly decreases or the dissonant voltage is materially lower than the applied voltage at which the current suddenly increases, namely, the resonant voltage. Advantage is taken in the form of my invention shown in Fig. 3 of this difference in resonant and dissonant voltages of the non-linear resonant circuit 20. Thus when lamp 7 is illuminated as a result of the decrease in impedance of reactor 10, the voltage applied to the non-linear resonant circuit must decrease from the resonant voltage to the dissonant voltage thereof before the current supplied to the rectifier 12 of the first branch is decreased sufiicient to substantially deenergize the saturating winding 11 of the reactor asso ciated therewith and thereby to cause the first lamp 4 to be extinguished. Similarly when lamp 7 of the last branch is to be extinguished, the voltage applied to the non-linear resonant circuit 20 must rise from the dissonant value to the resonant value before saturating current will be supplied to the reactor of the first branch. The sudden variations in current in the non-linear resonant circuit are prevented from causing any flicker of the lamps by the presence of the capacitor 23 for the reason already described above.

Although I have chosen to illustrate my invention as having a small number of branch load circuits the actual number of branch circuits used may be anything desired. The number may even be reduced to a single load circuit in which case the load, if a lamp, operates as a single flashing light or beacon. Such a modification is shown by Fig. 5 where the period of operation is controlled, for example, by the non-linear resonant circuit 20 as in Fig. 3. While I have spoken of lamp 4 as being in the first branch of the series and of lamp '7 as being in the last branch thereof the series in reality is endless, the operation of lamp 4 following that of lamp '7 after a somewhat greater delay than that after the operation of each of the other lamps.

For the sake of simplicity I have shown the saturable core reactors 10 in a. purely diagrammatic manner. Their actual construction may, for example, be as shown in Fig. 6 where the core of reactor 10 has four legs, the alternating current winding of which comprises the coils 27 and 28 wound in opposite directions on the two inner legs of the core and connected in parallel in the alternating current branch circuit and where the saturating winding 11 which comprises the single coil 29 surrounds both of said legs. A reactor of this type is disclosed in the Alexanderson Patent No. 1,328,610, January 20, 1920. Instead of a single core reactor I may employ two separate transformers 30 and 31 as shown diagrammatically in Fig. '7. These transformers respectively have saturating windings 32 and 33 which are shown connected in series and alternating current windings 34 and 35 shown connected in parallel. windings 34 and 35 are shown reversed in order to prevent alternating current from being introduced in the direct current circuit.

I have chosen the particular embodiments described above as illustrative of my invention, and it will be apparent that various other modifications may be made without departing from the spirit and scope of my invention, which modifications I aim to cover by the appended claims.

What I claim as new and desire to secure by Letters Patent in the United States is:

1. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith, each including a load device, time delay variable impedance means in each branch responsive to the current in the preceding branch, and means providing a greater time delay responsive to the current in one branch of the series for controlling the 1mpedance of another branch thereof.

2. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, a saturable core reactor in each branch circuit for varying the current therein in response to the current in a preceding branch circuit with a predetermined time delay and means responsive to the current in one branch circuit for providing an additional time delay in the current variation in the next branch circuit of the series.

3. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, time delay means including a saturable core reactor in each branch circuit for controlling the current therein, each reactor having a saturating winding responsive to the current in the preceding branch of the series, and additional time delay means for controlling the current in the saturating winding of the reactor in one branch of the series in accordance with the current in a preceding branch thereof.

4. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, a saturable core reactor in each branch circuit responsive to the current of the preceding branch, anda relay responsive to the current in the last branch of the series for controlling the reactor of the first branch.

5. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, a saturable core reactor in each branch circuit responsive to the current of the preceding branch, and a relay responsive to the current in the last branch of the series for controlling the reactor of the first branch, said relay having a capacitor connected across the winding thereof whereby the impedance of the relay in closed circuit position is the same as in open circuit position.

6. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, a saturable core reactor in each branch circuit responsive to the current of the preceding branch, and a non-linear resonant circuit responsive to the current in one branch of the series for controlling the reactor of another branch.

7. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, a saturable core reactor in each branch circuit responsive to the current of the preceding branch, a series non-linear resonant circuit connected across the reactor of the last branch for controlling the saturation of the reactor of the first branch.

8. A sequence. operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each including a load device, a saturable core reactor in each branch circuit responsive to the current of the preceding branch, a non-linear resonant circuit responsive to the current in the last branch of the series for controlling the reactor of the first branch, and a capacitor connected across said non-linear circuit whereby the impedance of the non-linear circuit is the same whether the circuit is in resonant or non-reso-e nant condition.

9. A sequence operating system comprising an alternating current supply circuit, a series of branch circuits connected therewith each includin a load device, a saturable core' reactor in each branch circuit responsive to the current of the preceding branch, a relay responsive to the current in the last branch of the series for controlling the reactor oi the first branch, and a rectifier connecting the relay with said last branch.

10. In combination, an alternating current circuit, a saturable core reactor therein for con trolling the current flow in the circuit and a relay connected to be responsive to the voltage across said reactor for controlling the saturation thereof.

11. In combination, an alternating current circuit, variable impedance means therein for controlling the current in the circuit comprising a saturable core reactor having a saturating winding, and a relay having a winding connected across said reactor and having contacts arranged to control the current in said saturating winding.

CHAUNCEY G. SUITS.

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