US2701325A - Control for relay circuits - Google Patents

Description

Feb. 1, 1955 w. M. ALTHERR 2,701,325

CONTROL FOR RELAY CIRCUITS Filed April 20, 1951 2 Sheets-Sheet l F|G 6:00AM. TO 5:59 PM.

' 4 F|G.3 6:00 PM.TO 5:59 AM.

Feb. 1, 1955 w. M. ALTHERR 2,701,325

CONTROL FOR RELAY CIRCUITS Filed April 20, 1951 2 Sheets-Sheet 2 CONTROL FOR RELAY CIRCUITS Walter M. Altherr, St. Louis, Mo., assignor, by mesne assignments, to A. B. Chance Company, Centralia, Mo., a corporation of Missouri Application April 20, 1951, Serial N 0. 222,116

2 Claims. (Cl. 317-132) This invention relates to controls for relay circuits, and more particularly to such controls as are used in street lighting systems to operate relays to turn street lamps on and OK.

The invention is particularly adapted for use in a street lighting circuit such as disclosed in my copending application entitled Circuit-Relay Apparatus, Serial No. 221,229, filed April 16, 1951. In said copending application I disclose a street lighting system wherein thermostatic relays each controlling a group of street lamps are in turn controlled by a control switch which is operated to transmit a pulse of current of such duration as toinsure that all of the relays operate to turn the groups of street lamps controlled thereby on or oil, as the case may be. This invention pertains to a control which fulfills the function of this control switch in a most reliable manner, and which may be economically manufactured. As herein illustrated, the control of this invention utilizes certain features of construction of the relay itself shown in said copending application, making it economical for the manufacturer to provide both said relays and controls therefor, inasmuch as they have interchangeable parts.

In general, it is to be noted that the control of this invention is applicable to any relay circuit, whether a street lighting system relay circuit or otherwise, where it is desired to effect operation of the relays in the relay circuit at periodic intervals by transmitting a pulse of current of limited duration through the relay circuit to operate the relays. As related to the control of street lighting systems, the control of this invention is particularly adapted to transmit a pulse of current at the time for turning on the lamps, this pulse operating the relays to effect closure of the lamp circuits, and to transmit a pulse of current at the time for turning off the lamps, this pulse operating the relays to effect opening of the lamp circuits.

In general, a control constructed in accordance with my invention comprises first and second terminals for connection in a relay circuit. A first double-throw switch is provided for alternately effecting connection of the first terminal to one or the other of two branches between the terminals. A second double-throw switch is provided for alternately effecting connection of the said branches to the second terminal. An electrically actuated timedelay means is provided for elfecting time-delayed operation of the second double-throw switch whenever the first and second double-throw switches are in position for flow of current between the terminals. With this arrangement, assuming that the switches are in position for flow of current between the terminals, the electrically actuated means will be energized and after a time delay will operate the second double-throw switch to break the established circuit and thereby deenergize the electrically actuated means. Thus, a pulse of current is transmitted prior to the operation of the second double-throw switch, this pulse being of a duration determined by the time-delay characteristic of the electrically actuated means. Then, the first double-throw switch remains in the position which it had to begin with. Subsequently, upon throwing of the first double-throw switch to its alter- United States Patent nate position, the circuit through the electrically actuated means is again closed, and another pulse of current of the said duration is transmitted, this pulse continuing until the electrically actuated means operates the second double-throw switch. Other features will be in part apparent and in part pointed out hereinafter.

2,701,325 Patented Feb. 1, 1955 The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Figs. 1 to 4 are circuit diagrams illustrating the basic principles of the control of this invention, and showing parts thereof in diiferent operating conditions;

Fig. 5 is a front elevation of a unit incorporating the second of the above-mentioned double-throw switches and the electrically actuated time-delay means therefor;

6 is a vertical cross section taken on line 66 of 1g.

Fig. 7 is a vertical cross section taken on line 77 of Fig. 5;

Fig. 8 is a horizontal cross section taken on line 8-8 of Fig. 5;

9 is a vertical cross section taken on line 99 of 1g.

Fig. 10 is a fragmentary side elevation as viewed from the right side of Fig. 5 illustrating in solid lines an intermediate position of a thermostatic element, and indicating in dotted lines an initial position of said thermostatic element; and,

Figs. 11 and 12 are views similar to Fig. 10 illustrating moved positions of parts.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

First referring to Figs. 1 to 4, which illustrate the basic principles of the control of this invention, there is shown at 1 a first terminal and at 3 a second terminal. These terminals are for connection of the control in a relay circuit designated 5. Several series-connected relays in this relay circuit are shown at 6, and it will be understood that as many relays as desired may be connected in this circuit for control. Here it may be said that the terminals 1 and 3 correspond to the terminals of the switch C shown in my aforesaid copending application, and that the connection of relays and lamps may be made in the same manner as therein illustrated.

At 7 is shown a first double-throw switch for alternately effecting connection of the terminal 1 to one or the other of two branches 8 and 9 between the terminals 1 and 3. At 10 is indicated a second switch, which is basically a double-throw switch, for alternately eliecting connection of the branches 8 and 9 to the terminal 3. At 11 is generally indicated an electrically actuated timedelay means for operating the second double-throw switch 10 whenever the switches 7 and 10 are in position for flow of current between the terminals 1 and 3. This means will ultimately be more particularly described. It suffices to say at this point that the time-delay means comprises a spiral bimetallic electrically conductive thermostatic element 35 which controls the operation of two cams 2 and 4 which actuate sets of contacts D and S of the switch 10. The thermostatic element 35 is connected so that current flows therethrough whenever the switches 7 and 10 are positioned for flow of current between the terminals 1 and 3. There are two such positions possible, these being illustrated in Figs. 2 and 4. Two other positions, in which no current can flow between the terminals 1 and 3, are illustrated in Figs. 1 and 3. When current flows through the thermostatic element 35, it heats up and, after a time delay, effects rotation of the cams to open those contacts of the switch 10 which were closed, and to close those which were open.

At 12 is diagrammatically shown a device for effecting operation of the first double-throw switch 9. This might be a conventional timer, or, particularly in the case of a street lighting system, a photocell-controlled device. For example, in the case of a street lighting system in which the lamps are to be turned on at 6:00 P. M. and turned ofl? at 6:00 A. M., and assuming that a pulse of one-minute duration is desired to operate the relays, the device 12 would be one that operates to throw the switch 7 from whichever position it was in at 5:59 P. M. to the opposite position, and to throw it back at 5 :59 A. M. As a matter of fact, the switch 7 might even be manually thrown at these times, if desired.

Figs. 1 to 4 illustrate the operation as related to a setup for throwing the switch 7 at the above noted times, and for obtaining a relay-operating pulse of one minute duration. Fig. 1 illustrates the status of the control during the time from 6:00 A. M. to :59 P. M. Contacts D are closed and contacts S are open. During this time the street lamps are off. The switch 7 is in position effecting a connection from the terminal 1 to the branch 8, but branch 8 is open at the contacts S. Consequently there is no fiow of current between the terminals 1 and 3.

At 5:59 P. M. the switch 7 is thrown to the Fig. 2 position in which it connects branch 9 to the terminal 1. Inasmuch as contacts D of the second double-throw switch 10 are closed at this time, current flows between the terminals 1 and 3 and through the thermostatic element 35 and energizes the relay 6 to turn on the street lamps. After a time delay of one minute, assuming that the thermostatic element is such as to give this time delay, the switch 10 is thrown so that contacts D open and contacts S close. This status is illustrated in Fig. 3. With the switch 7 remaining in position connecting terminal 1 to dbganch 9, no current flows between the terminals 1 an The Fig. 3 condition is maintained until 5:59 A. M. At 5:59 A. M., the switch 7 is thrown back to the position wherein it connects terminal 1 to the branch 8. Inasmuch as the contacts S are now closed, current fiows from the terminal 1 through the thermostatic element 35 to the terminal 3, and hence the relay circuit 5 is energized to operate the relay 6 to turn off the street lamps. This flow of current is maintained for one minute, at which time the thermostatic element 35 is heated sufficiently to effect operation of the cams 2 and 4 to open the contacts S and close the contacts D. This brings the control back to the condition illustrated in Fig. 1. The entire operation is repeated every twenty-four hours.

Figs. 5-12 illustrate the details of a form of unit which I have used incorporating the double-throw switch 10 and the electrical-actuated time-delay means 11. As shown therein, this unit includes an insulating base 19 on which is supported a generally U-shaped conductive frame 21 having legs 23 and 25' and an upper arm 55. Extending from the leg 23 is a conductive hollow threaded stud 27 which is axially slotted as shown at 29. This studaccepts a. pintle 31 which forms a bearing support between the legs 23 and 25. This pintle is flattened out as at 33 m key into the slot 29. Around the stud 27 is located the spiral bimetallic conductive thermostatic element 35 which has a central tongue 37 keyed into the slot 29. This thermostatic element 35 is flanked by two porcelain enameled protective washers 39 which have both heat-resisting and insulating properties. A lock nut 41, threaded to the stud 27, serves to clamp the central part of element 35 between offset central portions 36 of the washers. The resulting reactions hold the stud 27 in place. Its angular position may be adjusted by loosening the lock nut 41, and turning 27 by means-of a screw driver in slot 29 and then again tightening the lock nut. This adjusts the angular position of the center of the thermostatic element 35 and hence its operating characteristics, as will appear. Tongue 37 in slot 29 axially positions the pintle 31, as shown in Fig. 8. Thus the thermostatic element 35 is centrally anchored and in conductive relation to ge frame 21. A terminal for the frame is provided at Around the pintle 31 is located a sleeve 43. This sleeve is located within a circular hole in a rotary camshaft 45 which is in the form of a polygonal bushing. The camshaft 45 carries in keyed relation (by reason of its polygonal form; Figs. 6 and 7) an eight-toothed ratchet 47, an insulating spacer 49, an insulating washer 51, and the cams 2 and 4. The ends of the camshaft 45 are upset, as shown, to hold together as a unitary rotary assembly the parts 2, 4 and 47. Cams 2 and 4 are composedof insulating material; ratchet 47 is not, although it might be.

Wound around the spacer 49 is a helical spring 53 which has one end anchored in the extension 55 from the leg 25, as indicated at 57 in Fig. 5. The other end of this spring is formed as a bail 59 having a leg 61 and a leg 63. The inner end of leg 63 forms a loose wrap 65 around a groove 67 in the nut.41. Thusthespring at one end is anchored at 57 but the wrap 65 at the other endis rotary in the groove 67.

The thermostatic element 35, except at its anchored central position, is free and spirals to its outer end 69 where it is provided with an insulating collar 71 engageable with the bail 59. When the thermostatic element 35 cools, it tends to unwind in counterclockwise direction as viewed in Figs. l012, thus forcing the bail 59 toward a stop 73 which forms an extension from the leg 23. This increases the tension in the spring 53, which has been prewound prior to anchoring at 57, so as to bias its bail in clockwise direction as viewed in Figs. 10-12. When the thermostatic element 35 heats, it tends to wind in clockwise direction as viewed in Figs. 1012 and the tensioned spring 53 follows it, as illustrated in Fig. 10. After following to a certain point, the leg 61 of the bail 59 is caught behind one of the laterally directed teeth 75 of the ratchet 47. At this time the ratchet is prevented from moving clockwise because of engagement by another one of its teeth 75 with a spring pawl 77. This spring pawl is anchored at its lower end, as shown at 79, to an insulating block 81. The pawl 77 biases counterclockwise, the motion being limited by engagement of its upper end 03 with a second stop 85 extending from the leg 23. This stop is for the purpose of allowing only enough counterclockwise movement of pawl 77 to latch under a tooth 75 without acting as a friction brake on the ratchet 47. Upon continued heating of the thermostatic element 35 it moves from the Fig. 11 to the Fig. 12 position, leaving behind the bail 59, which then applies the tension of spring 53 to ratchet 47, but the ratchet is held against clockwise movement by the pawl 77 After a period of further heating the insulating collar 71 engages an offset end portion 84 of the pawl 77 This disengages the pawl 77 from the ratchet 47, and the bail 59 of the spring 53 advances the ratchet one-eighth turn with a snap action (compare Figs. 11 and 12). The movement of bail 59 is limited by its engagement with the stop 85 to limit rotation of the ratchet to one-eighth of a turn. When the spring 53 snaps, stop 85 prevents bail 59 from striking the insulating collar 71 to avoid damage to the collar. Pawl 87 is anchored at 88 to an insulating block 90. The pawl 87 also prevents reverse movement of the ratchet 47, when the thermostatic element 35 cools sufficiently to move it counterclockwise from the Fig. 12 through the Fig. 11 and Fig. 10 positions to its initial position illustrated in dotted lines in Fig. 10. During this counterclockwise movement the collar 71 reengages the bail 59 and the spring 53 is rewound. During clockwise heating movement of the thermostatic element 35 it is at first aided by the unwinding action of the spring-mounted bail 59 (Fig. 10) and thereafter may freely move without resistance until it releases the pawl 77. Therefore, its heating movement toward its tripping position for pawl 77 is relatively unimpeded, which means that this action may take place rapidly and reliably. The thermostatic element 35 is provided at its end beyond the insulating pad with a conductive arm 89 to which is attached a flexible conductor 92 for connection to the above-mentioned terminal 3. As will be apparent, the circuit to the thermostatic element is broken upon tripping of the switch, and thermostatic motion of the element 35v in a reverse direction occurs as the element cools. Hence the movement of the arm 89 is limited.

The double-throw switch 10 includes the two sets of contacts D and S previously referred to. Each of these, as illustrated, is provided as a bank of contacts. The details of each bank D and S are the same, and the description of one will serve for both, and the same reference numerals are used for each. Each bank of contacts D and S has mounting spring fingers 91, 93 and 95, insulated from each other and from the frame by blocks of insulation 97. Outer fingers 91 and 95 are conductively connected as indicated at 99. The middle finger 93 of each bank carries a terminal 101 for connection with the aforesaid branches 8 and 9. A terminal 102 is provided for each of fingers 91 and 95, each including bolt connection 104 in conductive relation to a finger 91, and hence (in view of connector 99) in conductive relation with both fingers 91 and 95. Terminal 102 on bolt 104 is connected by a wire 111 to frame terminal 96 (Figs. 1 and 7), in this particular instance. Bolts 104 are not in conductive relation with fingers 93' (see insulating sleeve 94). Behind each finger 95 is a pressure spring follower finger 103 for following engagement with the respective cam 2 or 4 for operating the spring fingers 91, 93 and 95 to closingand opening positions.

Contacts 107 on the fingers 93 and: 95 are preferably composed of a tungsten-silver alloy or the like, which has a high melting point preventing them from welding together during operation. After one or two operations of such contacts they become somewhat burned and oxidized, thus setting up a relatively high contact resistance.

The cams 2 and 4 are identical. Each is a four-lobed cam. The cam 2 operates the contacts D. The cam 4 operates the contacts S. The cams are mounted on the camshaft 45 out of phase 45'. The arrangement is such that when one cam holds its set of contacts closed, the other set of contacts is open. For example, Fig. 6 illustrates the earn 2 holding contacts D closed, and Fig. 7 illustrates the corresponding position of the cam 4 wherein contacts S are open. Upon rotation of the camshaft through 45 (one-eighth of a turn) from its position shown in Figs. 6 and 7, contacts D open and cam 4 closes contacts S. Upon another one-eighth turn, contacts S open, and contacts D are closed, and so on. Thus, each heating pulse of the thermostatic element 35, which effects a one-eighth turn of the camshaft 45, results in opening of the previously closed set of contacts D and S, and closure of the previously open set of contacts.

Contacts 105 on the fingers 91 and 93 are preferably composed of coin silver, which has a high conductivity, although a low melting point. The low melting point is acceptable because these contacts 105 are nonarcing shunt contacts which close only after closure of the circuit by contacts 107 and open before opening of contacts 107. Thus they never carry an open-circuit voltage drop. Moreover, they provide a low resistance shunt around high resistance contacts 107 when the latter are closed. As above implied, during closing action of the circuit, contacts 107 close first, and then 105. Thus high-resistance contacts 107 protect contacts 105 against initial inrush of current. Upon opening action, contacts 105 first separate without voltage across them and finally contacts 107 open. Any arc that tends to be formed will be handled by contacts 107. Since these are of the high-melting variety, they do not melt but maintain the desired high-resistance burned or oxidized condition, useful on the next closing action. In order to protect contacts 105 against voltages as from lightning surges or the like, the end of spring strip 93 is bent toward and over the end of strip 91 to provide a small surge gap 109.

The contact bank arrangement is particularly adapted for contact protection against high inrush-current, this protection being required where the device is employed in incandescent lamp circuits, as described and claimed in the aforesaid patent application. It will be understood that the load effect of the thermostatic element 35 does not require this contact protection.

As above-mentioned, branches 9 and 8 leading from the double-throw switch 7 are connected to the terminals 101 of the contacts D and S, respectively. When the switch 7 is in position connecting terminal 1 and the branch 8, and when contacts S are closed (Fig. 4), a current path is established from the terminal 1 through the switch 7, the branch 8, the closed contacts S to either of the terminals 94, thence through a connection 111 between terminal 94 and terminal 96, thence through the frame 21 (which is conductive) to the fixed end of the thermostatic element 35, thence through the e'ement 35 and the conductor 92 to the terminal 3. Similarly, when the switch 7 is in position connecting terminal 1 and the branch 9 and when the contacts D are closed (Fig. 2), a current path is established from terminal 1 through the switch 7, the branch 9, the closed contacts D, to the terminal 94, and thence through the connection 111 to terminal 96, thence through the frame 21 to the fixed end of the thermostatic element 35, and thence through the element 35 and conductor 92 to the terminal 3.

Operation is as follows:

When the switch 7 is thrown from the Fig. l to the Fig. 2 position, current fiows between the terminals 1 and 3 and heats up the thermostatic element 35. This current also energizes the relay 6. The time delay characteristic of the thermostatic element 35 is sufiicient to provide a pulse of current of sufiicient duration to operate the relay 6 (and any more relays there may be in the relay circuit). As the thermostatic element 35 heats up, it rotates clockwise from its initial position illustrated in dotted lines in Fig. 10 to the Fig. 12 position and, after its time-delay interval, effects rotation of the cams from the position illustrated in Fig. 2 to the position illustrated in Fig. 3 to open the contacts D and close the contacts S. When the contacts D open, inasmuch as the switch 7 is still in the position connecting terminal 1 to the branch 9, and not in position connecting the terminal 1 to the branch 8, the flow of current ceases. Assuming that the time-delay characteristic of the thermostatic element 35 is such that the cams are not rotated through their one-eighth step until the elapse of one minute from the instigation of current flow, the transmitted pulse will be of about one minute duration, or at least longer than the operating time of the slowest relay 6 in the circuit.

The duration of a pulse depends upon the current in the circuit and is regulated herein: by shunting the bimetallic thermostatic element 35 with a resistor 109 connected between the connection 111 and terminal 3 as shown in Figs. 1-4; by using a different type of thermostatic element; and, by changing the angular position of the slot 29 and screw 27 relative to the frame 23. It will be noted that the tension in the spiral thermostatic element is varied by adjustment of screw 27.

Then when the switch 7 is thrown from its Fig. 3 to its Fig. 4 position, connecting the terminal 1 to the branch line 8, since contacts S are closed, current again flows through the thermostatic element, for the one minute time interval, and at the termination of this 111- terval, the cams are rotated through a one-eighth turn to open the contacts S and close the contacts D. This restores the control to the status shown in Fig. 1.

It will be seen that the duration of the pulse is entirely dependent upon the time-delay characteristic of the means 11 including the thermostatic element 35, and is in no way dependent upon the period of time for which the switch 7 remains in one or the other of its positions. That is, simply by throwing the switch 7 to one or the other of its positions, the operation of the apparatus to transmit a pulse of predetermined duration is initiated, and at the termination of the desired interval, the pulse terminates, even though the switch 7 remains in the position to which it was thrown.

In view of the above, it will be seen that the several objects of the inventioin are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A street lighting system comprising a relay circuit, at least one relay connected in the relay circuit and operable in response to successive pulses of current in the relay circuit to make and break a street lamp circuit, and means for intermittently making the relay circuit to transmit a pulse of current in the relay circuit for operating the relay comprising first and second branch circuits in parallel, first and second switches connected in the relay circuit and adapted alternately to connect one of the branch circuits in series in the relay circuit, the first switch having a first position connecting to the first branch and a second position connecting to the second branch, the second switch having a first position connecting to the first branch and a second position connecting to the second branch, whereby the relay circuit is made via the first branch when both switches are in first position or via the second branch when both switches are in second position, an actuator for the second switch operable in steps successively to move the second switch between its first and its second positions, and electrical time-delay means connected in the relay circuit for flow of current therethrough whenever the two switches are in relay circuit making position and controlling the actuator to effect movement of the second switch from whatever position it is in to the other at the termination of the time-delay interval of the time-delay means, whereby a pulse of current of duration corresponding to the timedelay interval is transmitted in the relay circuit when, with the second switch in its first position, the first switch is thrown to its first position and also when, with the second switch in its second position, the first switch is thrown to its second position, and the timedelay and pulse interval being sufficient for relay actuation.

1 2. In a relay circuit as'set forth in claim 1 the time- .delay means including a conductive thermostatic element connected in the relay circuit to be energized and thereby heated upon flow ofeurrent in the relay circuit.

941,777 Hart Nov. 30, 1909 8 Anderson July 30,1935 Marbury Dec. 5, 1939 Wilkerson Aug. 1'3, 1940 LaForest Mar. 27, 1945 Smith Oct. 2, I945 'Rosing Mar. '16, 1948 Chandler June 19, 195.1

FOREIGN PATENTS Switzerland July ,1, 194.1

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