US3406360A

US3406360A - Protector switch

Info

Publication number: US3406360A
Application number: US628661A
Authority: US
Inventors: Simons Samuel Brian
Original assignee: Simons Samuel Brian
Current assignee: SAMUEL BRIAN SIMONS
Priority date: 1967-04-05
Filing date: 1967-04-05
Publication date: 1968-10-15
Anticipated expiration: 1985-10-15

Description

Oct. 15, 1968 K. KUPFERBERG ETAL unmmc LOADS FOR TESTING REGULATED POWER SUPPLIES Filed April 15., 1965 2 Sheets-Sheet 2 29 so l o 0 REGULATED POWER REMOTELY SUPPLY UNDER PROGRAMMABLE TEST CURRENT REGULATED '6 I5 POWER SUPPLY 5+ f +o o REMOTELY PROGRAMMABLE -32 2| VOLTAGE REGULATED POWER SUPPLY FIG 4 INVENTOR.

PAUL BIRMAN ATTORNEY Oct. 15, 1968 s. B. SIMONS 3,406,360 I PROTECTOR SWITCH Filed April 5. 1967 S Sheets-Sheet 3 Tia. 1m.

Tici. 1.5.

I NVE N TOR. SAM/4 flR/A/V S/MOA/s 8M5. Mam

ATTOE/UAV United States Patent 3,406,360 PROTECTOR SWITCH Samuel Brian Simons, 201 Westport Road, Wilton, Conn. 06897 Filed Apr. 5, 1967, Ser. No. 628,661 12 Claims. (Cl. 335-) ABSTRACT OF THE DISCLOSURE A high-current, low-voltage protector switch, as for motors, has sections each with one or more sets of stationary and movable contacts actuated by a cam in each section carried on a common shaft that is manually turned from an off or reset position to selected on positions for the contacts, the switch having bimetal high-current protective elements for the sections and a low-voltage electromagnetic protective element, all of the protective elements being operable directly on a common release shaft to release a trigger that actuates a settable spring-biased toggle. The toggle is initially spring-set by moving the switch camshaft to reset position, for setting individual release devices that are carried on shafts to which arms of the toggle are connected and that are arranged to shift the movable contacts to open position when the trigger is released for actuation of the toggle.

This invention relates to a switch adapted for use with electric motors and more particularly to a motor protector switch which is operated manually for controlling electrical motors and the like, e.g. as for starting, reversing or changing speed.

Motor protector switches have been known heretofore, their primary object being to protect an electrical motor as the motor is started and also to protect it against overloads. An example of one type of motor protector switch is exemplified by US. Patent No. 2,766,352, in which there is described a motor protector switch comprising an insulating body and a plurality of fixed and movable contacts. The latter contacts are moved into physical contact with the fixed switch contacts by the operation of a cam. The switch contacts remain in this position until they are automatically opened by a release mechanism. In other words, it is normally the case that once the switch contacts have been closed, they remain in the closed position until the release mechanism is actuated in response to a predetermined high-current condition. Bimetal elements are provided on the switch, and these elements operate responsive to the rise in temperature that results from the high-current condition and cause movement of the aforesaid release mechanism, thereby in turn to cause opening of the switch contacts.

The rotary, cam-operated motor protector switch described in the aforenoted patent is usefully applied for limited purposes. However, full protection is not afforded the motor by such a switch because there remains a serious lack caused by the fact that an under-voltage or no-voltage condition may arise in the operation of the motor, thereby causing serious damage to the motor. Although it has been known in certain more complicated switching or circuit-breaker applications to provide some means that will respond to an under-voltage condition, and likewise for certain on-oif types of switch, protection of this character has not been furnished previously in simple, manually operated, compact motor switches of the cam-controlled type, and especially in such switches which are adapted for simultaneouscontrol of multiple circuits and for effectuating various types of motor operation in a selective manner, such as forward, reverse, intermediate speed or the like.

.Low-voltage and no-voltage aspects of protection, as afforded by this invention, not only provide unusually 3,405,360 Patented Oct- 15, 1968 ICE ing power shut off until the switch or controller is restored.

to motor energizing condition by positive manual control.

Thus injury to personnel or damage to work by unexpected restarting of machines can be avoided, and surges or overloads dangerous to power lines or systems are prevented,

as might be occasioned if a large number of motors start simultaneously when voltage-is restored. Indeed in these and other respects, the controller herein described affords notably effective means for compliance with electrical or safety codes as to shut-off and restarting of motors and machines. v Accordingly the primary object of the present invention is to provide a simple, compact motor switch that will operate to afford complete protection to a motor.

Another object is to provide such a switch having the capability of responding with the simplest of mechanisms to a number of conditions that would be dangerous to the controlled motor.

A further object is to provide in a motor protector switch a compact package, including an under-voltage responsive mechanism that will operate in cooperation with the release mechanism of the switch to furnish full protection to a motor.

Another, particularly important object is to provide the foregoing capability in manually operable motor switches of the rotary cam-actuated type, adapted to con-- trol multiple circuits and to provide a plurality of circuit controlling positions, in addition to a conventional off position.

The preceding objects are realized in a cam-operated switch which may include a plurality of sections with actuating cam means extending through the sections and one or more sets of stationary and movable contact means in each section, ,the switch having an off or reset position of the cam means where all contacts are opened,

and another position or very preferably a plurality of further positions where selected sets of stationary and movable contacts are closed while other sets remain open. In such combination a basic feature of the inventionineludes the provision of an under-voltage releasing device which directly operates upon a release means, such release means being also directly actuated by thermally motivated high-current responsive means. In particular,

the combination includes shiftable means' or elements directly associated with the several movablev contact means, e.g. individual to each, together with means actuated from the shaft of the rotary cam system on manually turning such shaft to the off (reset) position,

whereby the shiftable elements are set to be released by a trigger element of the setting means. The release means, when actuated, is arranged to release the trigger in any of the positions of the switch where contacts are normally closed; thereby, e.g. in response to either of the highcurrent or low-voltage conditions, all movable contacts are shifted by the above-described elements to open condition, and remain so until the switch is manually moved to the reset position and then again to a selected on 1 contacts and affording maintained protection until a positive, manual resetting operation is effected.

In accordance with a more specific feature there is provided an arrangement including the basic means noted above wherein the trigger or setting mechanism or means is in the form of a spring-loaded toggle. The trigger portion of this means, including a pawl, is placed into its triggering or operative condition as a result of manual movement of the main cam means by the control means, e.g. the handle. One or more shafts extend through the switch assembly, carrying the shiftable elements associated with the several movable contact means; the trigger or setting means controls these contact-opening elements through coupling of the toggle to such shafts, so that when the trigger is released the shiftable elements are brought into play. Another shaft, traversing the assembly, includes means that engages the pawl or trigger and that is arranged for direct actuation (to release the trigger) by high-current-responsive means, e.g. one such means for each switch section, and by loW-voltage-responsive means compactly associated with the assembly.

In this fashion, pursuant to the present invention, a motor protector switch is provided, very usefully adapted to complex situations such as three-phase, reversing control or the like, which is directly or permanently responsive to both a high-current condition and. a lowvoltage condition, the latter means comprising a simple but effective coil structure that releases a core or like element when the voltage drops to zero or below a predetermined level. Hence an effective mechanism is provided in a cam-actuated, multiple position manual switch, useful for three-phase or other multiple-line functions, whereby direct, safety response is achieved from both high-current condtiions and low-voltage conditions, the

response being of a true protective character (rather than a mere temporary release) in that even after the restoration of normal electrical circumstances a positime manual reset is required in order to restart the motor or other machinery.

To the foregoing and other ends, and by way of example, a presently preferred embodiment of the invention is illustrated in the accompanying drawings, wherein:

FIG. 1 is a front elevation view of the motor protector switch of the present invention;

FIG. 2 is a rear view of the switch;

FIG. 3 is a plan view of the switch;

FIG. 4 is a fragmentary view in side elevation;

FIG. 5 is a section taken along the lines 55 of FIG. 4 with the switch in one on position but showing the trigger means released as by actuation of one of the protective devices;

FIG. 6 is a section identical with FIG. 5 but showing the parts in the off or reset position;

FIG. 6A is a fragmentary view showing the holding position of the trigger pawl after switch movement to a normal on position;

FIG. 6B is a fragmentary view showing the transient position of the trigger and detent immediately upon a protective release function;

FIG. 7 is a section along the line 77 of FIG. 4, showing the parts of a typical switch section with the cam means in a selected on position but with the contacts released, corresponding to FIG. 5;

FIG. 8 is a section along the line 77 of FIG. 4, showing the switch section of FIG. 7, with the parts in the off or reset position, corresponding to FIG. 6;

FIG. 9 is a fragmentary view showing the cam means and switch contacts of FIGS. 7 and 8, with the cam means in the selected on position of FIG. 7 and certain contacts closed in consequence of normal operation;

FIG. 10 is a fragmentary view similar to FIG. 9, but showing the cam means and switch contacts in another on, e.g. reverse position of the switch;

FIG. 11 is a fragmentary view similar to FIG. 10, showing parts of another switch section (as on line 1111 of .4 FIG. 4), having only one set of movable contacts and one set of fixed contacts; and

FIG. 12 is a wiring diagram of the switch, including its protective means, as arranged for forward and reverse control of a motor supplied from a three-phase source.

Referring now to the drawings, certain basic constituents of the motor protector switch are the control means designated 20 (which can be considered as part of, and operated with, the main cam assembly), and trigger and setting means comprising the setting device designated 40 and the trigger device designated 60. These basic constituents, as noted above, cooperate such that the control means when moved to the off or reset position causes the setting means to condition the switch contacts for both normal operation and release, and upon movement of the main control and cam means to any selected switch-closing position, the trigger means becomes operative, i.e. ready, for automatic release and opening of the switch contacts.

The various parts of the motor switch are contained by an insulating housing or carrier member 12. Thismember 12 includes a front section 12a, and three separating parts 12b, 12c and 12d which separate the three switch contact assemblies or sections that are utilized in this illustrative embodiment in order to provide three-phase control. A rear section 12e is provided upon whose rear wall a low-voltage responsive device is located for purposes to be explained hereinafter. .Although a complete switching unit for three-phase operation of a motor in forward and reverse directions has been depicted in the drawings, it will be evident that the principles of the present invention can be utilized in a wide variety of motor control systems as for single-phase reversing operation, double wire control for simple on-olf switching, and more complex manual controls such as may embrace intermediate speeds as well as forward and reverse. As will be appreciated, the cam means shown and described for actuating the switch contacts can be cut to have a variety of operating positions and the contact elements may be embodied in various arrangements, the drawing nevertheless illustrating a basic and particularly useful deployment of sets of fixed and movable contacts.

A front plate 14 is afiixed to the carrier member 12, and a handle 16, projecting beyond this front plate, is mounted on a shaft 18 for manual control of the motor switch. Thus, movement of this handle 16 causes movement of a cam 22 which is journaled on theshaft 18. The cam22 is so located on the shaft as to be contained within the section 12a of the carrier member 12. The handle 16 also turns the contact-controlling cam system (described below) on the shaft 18. Although a variety of positions and positional sequences can be utilized (e.g. depending on the cam system), the illustrated switch has an off (reset) position 16a where the handle is shown in full lines, and also an on position 16b for forward motor operation and an on position 16c for reverse, for example each displaced 60 from the central reset position 16a. In FIGS. 5, 7, 9 and 11, the handle 16 and shaft 18 are in forward position 16b; in FIGS. 6 and 8 they are in position 16a (oif or reset); and in FIG. 10, in reverse position 16c.

The setting means 40, also contained Within the same section 12a, comprises a symmetrical spring-loaded toggle 42. The toggle 42 is constituted of an upper part comprising a pair of levers 44a and 4412, one overlying the other in spaced relation, and a lower part comprising a lever 46. The toggle is spring-biased by means of the

springs

48 and 50. One of the ends of the

springs

48 and 50 is looped about the levers 44b and 46, respectively, and the opposite ends of the

springs

48 and 50 are looped about the

shafts

52 and 54, respectively, By virtue of the spring bias, the toggle is normally urged to the right into the position shown in FIG. 5. This corresponds with the released or triggered off state of the mechanism. This positioning of the toggle is due to the fact that the

aforesaid levers

44a, 44b and 46 "have a mutual pivot point 56. Abutting the cam 22 is the roller 58 which is journaled on a shaft between the extended portions of the spaced levers 44a and 44b.

The trigger device 60 is arranged for Cooperative interaction with the setting means 40. Thus the pair of levers 62a and 62b are pivoted together atpivot point 64 approximately midway of the lever 46. Attheir other ends the pairs of levers 62a and 62b are pivoted at point 66 at the lower extension of a pawl 68. The pawl 68 is mounted for rotation on a shaft 70. Associated with the trigger means 60 is a controllable release means comprising a shaft 72, which extends from thefront of the carrier member 12, as seen in FIG. 5, all the way back to the rear of the last section 12e of the carrier' member 12. Integral with the shaft 72, at the front end thereof shown in FIG. 5, is a downwardly extending arm 74 which is spring-biased bythe action of the spring 76 against a stop. This stop is in the form of a screw 78 with a flat side abutting the arm 74. Also integral with the shaft 72 is a forwardly projecting cam or detent 80 which, with the shaft 72, can be slightly changed 'in the position of rest, by adjustment of the screw 78. The purpose of this cam 80 is to catch the tip of the pawl 68, thereby to retain the trigger means 60 in operable position so as tohold the setting means 40 in the condition permitting normal camcontrol of the contacts, as will be described more fully hereinafter.

A typical set of switch contacts is shown in FIG. 7. The switch contacts, and associated elements shown therein, are designed to be contained by the interfitting, insulating carrier member sections 12a and 12b. The switch contacts consist of the sets of fixed

contacts

102a and 102b, and 104a and 104b; and the sets of

movable contacts

106a and 106b, and 108a and 108b. The movable contacts are carried on

arms

110 and 112, and these arms are spring-biased on

shafts

114 and 116.

Shafts

114 and 116 are movably mounted in the

levers

118 and 120, respectively, and these levers are in turn mounted for rotation on the

shafts

52 and 54, respectively. The

shafts

52 and 54 extend through the carrier member section 12a and as noted previously are affected by the position of the toggle 42.

Afiixed to the

contact arms

110 and 112 respectively are

U-shaped guides

111 and 113. The rearmost portions of these guides (not seen in FIG. 7) ride in the

slots

115 and 117 provided in carrier member section 12b. The foremost portions of the guides (seen in FIG. 7) ride in corresponding slots provided in the rear wall of the adjoining carrier member section 120. Also provided is a pair of cam follower pins or

rollers

119 and 121. These pins ride in the described slots and coact with the cam 123 for purposes to be explained hereafter.

Current is supplied through the switch, e.g. to alternately energized connections of a motor or other controlled device, by means of the

terminals

122 and 124, as will be apparent. The conductors normally connected to these terminals have not been shown in FIGS. 7 and 8. Afiixed at the opposite end of the fixed contact assembly is a high-current detection means in the form of a structure of conventional bimetal elements 128 guarded by a shield 126. These bimetal elements 128 are those conventionally used to respond to a temperature rise due to the passage of current through the elements. Current flows to either of the separated

terminals

122 and 124 through the stationary and movable switch contacts, to which there is a common current path through the bimetal elements 128 from the terminal 130. Insulation, not shown in detail, is provided in the mounting assembly 129 so that there will be a path only through the bimetal elements. In a well-known manner, the passage of current through the bimetal elements 128 will cause differential expansion, with the result that these elements will push against the adjusting screw 132. This adjusting screw projects through the rocker arm 134 which is affixed to the shaft 72. This point on the shaft 72 is, of course, of smaller diameter than the portion which appears in FIG. 5. a

As will best be seen in FIGS. 2 and 3, an under-voltage release device 150 is secured to the rear of the carrier member 12. In the case of the illustrated switch, this device 150 is mounted at the rearmost section 12c and the shaft 72 extends through the entire three-phase assembly.

The under-voltage release device 150 comprises basically a solenoid member including a coil 152 and a plunger 1 54. The foregoing elements are mounted on a bracket which is secured to the rear of the carrier member 12. A pair of terminals 156a and 15611 of the coil 152 are provided for circuit-connecting purposes. Adjacent to plunger 154 for actuation thereby is a lever 158, whose upper end is secured to the shaft 72, e.g. being bent about the shaft 72 and affixed thereto by set screw 160. In order to adjust the limit of travel of the lever 158, or'to keep it immovable when desired, a screw 162 is provided.

The complete operation of the switch of the present invention as illustratively embodied will now be considered. Referring first to FIGS. 5 and 7, it will be assumed that the switch is in the state where it has been triggered or released by one of the protective devices 128 or 150. The cam 22 is in the position shown with the handle 16 in one of the on positions, i.e. the forward position 16b (as depicted in FIG. 1). Under the assumption made, for the released position of the

elements

118, 120, the

movable switch contacts

106a and 106b, 108a and 108b, are kept spaced from their respective fixed

contacts

102a and 102b, 104a and 10412 (as depicted in FIG. 7), regardless of the state of control of these contacts by the cam 123 and pins 119, 121. This is for the reason that the toggle 42, under its spring-bias, has been forced into the position shown in FIG. 5 whereby the

shafts

52 and 54 have been rocked and, consequently, the

levers

118 and 120 hold the

contact arms

110 and 112 away from the fixed contact assembly.

When handle 16 is rotated counterclockwise to the reset (off) position 16a (FIG. 1), the eccentric portion of the cam 22 is forced against the roller 58 thereby forcing the toggle 42 against the action of the

springs

48 and 50 and into the so-called ?set condition as aforenoted and as illustrated in FIG. 6. At the same time the trigger device 60 is moved; that is to say, the cooperating levers 62a, 62b and the pawl 68 are moved to a new position.

The tip of the pawl 68 strikes the cam in passing; but,

of course, the cam 80 is free to move in this direction against the urging of spring 76. At this juncture, with the toggle 42 in the position shown in FIG. 6 and with the

shafts

52 and 54 having been rocked to their nonreleased or normal position, the

levers

118 and 120 have caused the contact arms and 112 to move towards the fixed contact assemblies, i.e. so that the cam system' exemplified by the cam 123 may operate to close selected circuits as desired. However, because the handle 16 is now in the off position (reset), the shaft 18 and with it the cam 123 are in such (olf) position'(FIG. 8) where the cam follower pins 119 and 121 are riding on the high portions of the cam 123 and are effective to prevent the spring-biased

shafts

114 and 116 from producing closure of the contacts. Thus, the movable contacts 106a and 106b on arm 110 and movable contacts 108a and 108b on arm 112 must remain spaced from their respective fixed contacts 102a, 1021) and 104a, 10'4b.

However, when the handle 16 is returned to an on position, e.g. the forward position 16b (see FIG. 1), corresponding to FIGS. 5 and 7, the situation for the switch contacts is as depicted in FIG. 9. As shown there, the movement of the shaft 18 back to this on position allows the pin 119 to move into a depression 123a in the cam 123 thereby allowing the movable contacts 106a, 10Gb to move into actual physical contact with their opposed fixed

contacts

102a, 102b, closing the circuit between

terminals

130 and 122. The other pin 121, in the switch structure shown, keeps the other contact group open at this time, for a desired open circuit to the terminal 124. Also, when the handle 16 is in an on position, the toggle 42 is no longer free to return, even though the cam 22 has been moved to the location of FIG. 5. This is for the reason that the-tip of the pawl 68 is caught by the cam or detent 80, and the pawl therefore cannot move counterclockwise. This engagement of the pawl can be deemed to occur, in effect, in the reset condition of FIG. 6, but fully occurs (if there is any slight play in the mechanism) on movement of the cam 22 away from the position of FIG. 5, e.g. as seen in FIG. 6A. As a result, the toggle 42 is retained in its releasable set position, permitting the desired, normal, circuit-controlling operation of the switch, and the contacts which have been closed, remain closed. The trigger means 60 is now rendered operative for its assigned task, namely, to respond to a plurality of dangerous conditions for opening the switch automatically and keeping it open until manually reset.

In order to prevent damage to the motor the high current detection means 128 is thus arranged to operate in response to a predetermined excessive current to actuate the controllable release means. In the normal position of these bimetal elements 128, they are out of contact with the adjusting screw 132 on the lever 134. Should a high-current condition occur, however, the heating effect of excessive current flow will cause differential expansion of the elements 128, bending them to strike and displace the screw 132 and its arm 134. This action, as shown in FIG. 6B, will rock the shaft 72 counterclockwise and in turn so move the detent 80 as to release the pawl 68, thereby allowing the toggle 42 to return to the position shown in FIG. 5, causing opening of the switch contacts.

The point at which the controllable release means operates to release the pawl 68, can be independently radjusted by adjustment of the dial 140, which modifies an eccentric mounting in a well-known manner. By such adjust-ment the tip of the pawl 68 is movable with respect to cam 80.

It is a notable feature of the present invention that the same controllable release means, operable for all sections of the switch, is also actuated in response to a low-voltage condition. Moreover, the device for this purpose, i.e. solenoid member 150, acts directly upon the controllable release means, that is, it acts to strike the lever 158 which causes rocking of the shaft 72 to release the trigger means 60, thereby to open the switch contacts. This occurs because the plunger 154 is normally biased against the action of its associated spring 164 into the position shown in FIG. 2. That is to say, in normal operation the voltage is sufficient so that sutficient current is supplied to the coil 152 of the solenoid member 150. The current is, of course, supplied to the coil by the conductors 166, 168 from the terminals 156a and 1561). However, when the voltage drops to an insufiicient value and the current therewith, there will not be sufiicient force to retain the plunger 154 in its withdrawn position, and it will move under its spring bias so as to strike the lever 158, hence causing rocking of the shaft 72 with the aforenoted effect.

As will now be understood, the function of the setting and release means is the same for all on positions of the switch. Thus after turning the handle 16 to the reset location 16a (FIG. 1), it may be moved counterclockwise to the reverse (on) position 160, where the pawl 68 is likewise in engagement with the detent 80, and where the operating condition of the contacts is as shown in FIG. 10. Here the pin 121 lodges in another recess 12311 of the cam 123, and permits the movable contacts 10 8a, 108b to close with the fixed contacts 104a, 104b, while the other pin 119 rides on a high portion of the cam and keeps the mova-ble contacts 106a, 1061) open relative to the fixed

contacts

102a, 102b.

As stated, an important aspect of the invention is the embodiment of both high-current and under-voltage protection in a manual cam-actuated motor switch of multi- 8 ple type, as for reversing, three-phase control. Thus in the switch shown, the switch section carried by the structure 126 (FIGS. 3 and 4) is identical with that illustrated for portion 12b in FIGS. 7, 8, 9 and 10, including contactopening releasable elements on shafts 52 and 54 (like the elements 118, and a bimetal device similar to the means 128. Likewise the third section located at 12d, shown in FIG. 11, may be the same, except that for reversing three-wire control the connection is closed for both on positions in one lead, e.g. this third one, and therefore only one set of

movable contacts

1060, 106d and coacting fixed contacts 1020, 102d is needed; the cam 123' then has two recesses 1230 and 123d disposed tocoact with the single pin 119a so that in the forward position 16b (shown) contact closure is permitted by the recess 123:: and in the reverse position 160 by the recess 123d.

It will be understood that the arrangement of contacts and

actuating cams

123, 123', shown in FIGS. 7, 8, 9, l0 and 11, and further described above for a reversing switch, is given for purposes of illustration, and the switch is capable of a variety of cam and contact relationships, e.g. in each of the sections such as 12b, 12c, 12d and so forth, and indeed differently in each section, as may be desired. With an appropriate number of switch sections and with appropriate numbers and arrangements of cam recesses in the several sections of a multiple-unit switch, many types of circuit-controlling functions are readily attainable for selective manual operation in a single assembly.

FIG. 12 shows a circuit embodying the switch of FIGS. 1 to 10, for controlling a three-phase motor 190 from a corresponding three-phase source of current connected to switch terminals a, 1301) and 130a. The circuits respectively extend through the heaters of the bimetallic control devices 128a, 1281; and 1280 to a contact set 191 in one switch section and to pairs of contact sets 192, 193 in the two other switch sections. As will now be understood, the arrangement of the sections and sets 192 and 193 may each be as shown in FIGS. 7, 8, 9 and 10, while that of the contact set 191 can be as illustrated in FIG. 11, for a forward and reverse control of the motor 190. As will be seen, one motor terminal 195 is connected to the contact structure 191 so that in each contact closing position (see FIG. 11), a circuit from terminal 130a is completed, whereas the

other motor terminals

196 and 197 are connected to the

contact structures

192, 193 in a reversible manner such that the connections to the terminals 13012 and 1300 are reversed depending on the position of the switch unit, i.e. in closing either the upper or lower set of contacts as contemplated by the structure of FIGS. 9 and 10. As will be understood, all of the several switch contacts in FIG. 11 will be open when the switch is in the reset or off position (16a in FIG. 1), while contact closure for forward and reverse operations of the motor will be achieved with the rotary cam assembly in corresponding on positions, e.g. 16b and of FIG. 1.

The low voltage or no-voltage coil 152 may be connected in any suitable manner, such that it will be energized before or not later than the setting of the triggering means as by movement to the reset position (16a) shown in FIG. 6. Since this coil can conveniently be of a high resistance type, drawing only a small current, it may be permanently connected across the line or one set of lines as illustrated in FIG. 12, and may, if desired, have suitable supplemental controls (manual or automatic) as for example a separate control switch 198, manually closed before any use of the motor control system is to be initiated. Alternatively, the coil 152 can be connected else where to the power line for response to voltage condition of the latter, it being further contemplated that an element such as the coil 152 (or an additional one like it) may be responsive to other controlling conditions, as for example by becoming deenergized upon opening of a limit switch in equipment powered by the controlled motor.

It will be appreciated that in the preferred combination of the invention, the coil 152 is responsive to a predetermined drop in voltage so 'that it then exhibits insufiicientmagnetic forceto retain the plunger-or core-154, of

iron ortother magnetic material, in a fully'attracted posiing zeroelevel the release structure is triggered, actuating alhofthe switch contacts inthe' desired; fashion,- e.g. to

open position. Unless" otherwise "indicated, however, refcrences herein. to. devicesfunctioning on alow-voltagecondition are intended generically to include 'devi'ces which may, essence, respond-only to a no-voltage condition,. as well as devices; which 'operate whenathe vol-tage drops fro'm -normal.to.:a predetermined abnormal value.

It is: to be understood thatthe invention isnot limited to the specific structures herein shown and described but may be embodied in other forms without departure from itsspirit.

" 11 A protector' switch for motors and the like' comprisfir'stian'd second sets of friiutilallycoactmg stationary cdhtactmeansand movable contact means, rotatable "cam means adapted to be turned into and from a first position where the cam"mea-ns maintains all of the movable cori tact means outof engagement with-the stationarycontact means, and selectively to each of second and third positions for respectively effectuating engagement of said movable and stationary contact means of said first and second sets, said first and second sets of contact means being angularly spaced around the rotary path of said cam means, means associated with the movable contact means and shiftable to a released position for maintaining all of said movable contact means out of engagement with the stationary contact means in each of said second and third positions of the cam means, trigger means settable to a releasable position by turning said cam means to its first position and operable when released, to actuate said shiftable means when the cam means is in each of its second and third positions, release means movable to release the trigger means, and means responsive to a highcurrent condition and means responsive to a low-voltage condition, both directly operative upon said release means.

2. A protector switch for motors and the like comprising a plurality of switch sections each including stationary contact means and movable contact means, rotatable cam means extending through said sections and adapted to be turned into and from a first position where the cam means maintains the movable contact means of each section out of engagement with the stationary contact means of the section, and to a second position for effectuating engagement of said movable and stationary contact means in each section, a shaft extending through the sections, a plurality of devices on said shaft respectively associated with the movable contact means of the sections, each device being shiftable to a released position on turning said shaft for maintaining the associated movable contact means out of engagement with its related stationary contact means in said second position of the cam means, a trigger device associated with said cam means for simultaneously controlling all of said shiftable devices, said trigger device being settable to a releasable position by turning said cam means to its first position and operable when released, to turn said shaft to actuate said shiftable devices when the cam means is in its second position, release means movable to release the trigger device, and means responsive to a high-current condition and means responsive to a low-voltage condition, both directly operative upon said release means.

I 3. A protector switch as defined in claim 2, in which the trigger device has associated setting means comprising a spring-biased toggle connected to said shaft, for turning the shaft on release of the trigger device, said rotatable cam means including a cam element for moving said toggle into spring-set condition on turning the cam means to its first position. 5

4. A protector-switches defined in claim 2, in which at least one' of said switch sectionsinc'ludes asecond set of stationary contact means and movable contact means I angularly spaced around the path of the cam means from the first-mentioned set of contact means in said one section, said cam means being adapted to be turned to-a third positionfor effecting engagement of said second set of contact means while maintaining thefirst-mentioned set of contact means open' in said one section, a second shaft extending'through the sections and releasable by the trigger device, to be turned, and a device on said second shaft associated with said movable contactmeans of said second'set, shiftable to a released position on turning said '1- second shaft,-for-maintaining said movable contact means and saidstationary contact means of said second set out of engagement upon release of the trigger device when the cam means is in its second'andthird positions.

--5. A- protectorswitch as defined in claim 4, in which 1.1 the release means-includes a third shaft extending throughthesetion's, having 'means to release "the trigger device on turning said thirdshaft,-said'high-current andlowvoltage means being directly operative on said third shaft.-

- 6. A protector switch as defined in claim 5, in which the high-current responsive means comprises a plurality of thermally actuated means respectively associated with the switch sections and connected with the stationary contact means of the respective sections, each for turning said third shaft in response to a high current.

7. A protector switch as defined in claim 6, in which the low-voltage responsive means comprises electromagnetic means disposed adjacent one of the sections and including a normally energizable solenoid, for turning said second shaft upon absence of normal energization of the solenoid.

8. A protector switch as defined in claim 7, in which the trigger device has associated setting means comprising a spring-biased toggle connected to said first and sec ond shafts, for turning both said first and second shafts on release of the trigger device, said rotatable cam means including a cam element for moving said toggle into spring-set condition on turning the cam means to its first position.

9. A protector switch as defined in claim 8, in which the electromagnetic .ineans includes a core element movable into the solenoid when full normal voltage is applied to said solenoid, said element being spring biased to move outwardly of the solenoid and arranged to turn said third shaft upon such outward movement.

10. A protector switch as defined in claim 9, which comprises at least three switch sections each having at least one set of stationary contact means and movable contact means arranged to be brought into engagement on movement of the cam means into at least one of its said second and third positions, each such stationary contact means having one of the aforesaid devices associated therewith, mounted on one of said first and second shafts, and shiftable to released position as aforesaid for maintaining disengagement of the stationary contact means when the trigger device is released.

11. A protector switch for motors and the like comprising a plurality of switch sections each including stationary contact means and movable contact means, rotatable cam means extending through said sections and adapted to be turned into and from a first position where the cam means maintains the movable contact means of each section out of engagement with the stationary contact means of the section, and to a second position for etfectuating engagement of said movable and stationary contact means in each section, a first shaft extending through the sections, a plurality of devices on said shaft respectively associated with the movable contact means of the sections, each device being shiftable to a released position on turning said shaft for maintaining the associated movable contact means out of engagement with its related stationary contact means in said second position of the cam means, a trigger device associated 'with said cam means for simultaneously controlling all of said shiftable devices, said trigger device being settable to a releasable position by turning said cam means to its first position and operable when released, to turn said first shaft to actuate said shiftable devices when the cam means is in its second position, a second shaft having means to release the trigger device on turning said second shaft, a plurality of thermally actuated means respectively associated with the switch sections and electrically connected with the stationary contact means of the respective sections, each for turning said second shaft in response to a high current, and electromagnetic means disposed adjacent one of the sections and including a normally energizable solenoid, for turning said second shaft upon absence of normal energization of the solenoid.

12. A protector switch for motors and the like comprising stationary contact means, movable contact means, rotatable cam means adapted to be turned into and from a first position where the cam means maintains the movable contact means out of engagement with the stationary contact means, and to a second position for effectuating en- 1'2 gagement of said movable and stationary contact means, a first shaft, means on said shaft associated with the movable contact means and shiftable to a released" position on turning said shaft for maintaining said movable contact means out of engagement with the stationary contact means in said second position of the cam means, trig ger means settable to. a releasable position by turning said cam means to its first position and operable when re leased, to turn said first shaft to actuate said shiftable means when the cam means is in its secondposition, a second shaft having means to release the trigger means on turning said second shaft, and means responsive to a high-current condition and means responsive to a lowvoltage condition, both directly operative upon said second shaft.

References Cited UNITED STATES PATENTS 2,766,352 10/ 1956 .Enderli 200-116 2,938,980 5/1960 Jencks 335-2O 3,369,202 2/1968 Gryctko 335-20 BERNARD A. GILHEANY, Primary Examiner.

H. BROO'ME, Assistant Examin r.