US2683838A - Circuit control device - Google Patents

Description

July 13, 1954 B. o. AUSTIN ETTAL Fig.|.

2 Sheets-Sheet 1 .Insulation WITNESSES:

INVENTORS Boscum 0.Austin and Richard H.Hermon.

ATTORNEY July 13, 1954 Filed Nov. 16, 1950 B. O. AUSTIN ETAL CIRCUIT CONTROL DEVICE 2 Sheets-Sheet 2 Ill?) III WITNESSES:

INVENTORS Boscum O.Ausfin and Richard H.Hermon.

ATTORNEY Patented July 13, 1954 CIRCUIT CONTROL DEVICE Bascum 0. Austin and Richard H. Herman, Lima,

Ohio, assignors to Westinghouse Electric Corporation, East Pittsb Pennsylvania urgh, Pa}, a. corporation of ApplicationNovember 16, 1950, Serial No. 195,066

4 Claims. 1

Our invention relates, generally, to circuit control devices and, more particularly, to devices for controllin the operation of electromagnetically operated circuit breakers or contactors.

An object of our invention, generally stated,is to provide a device for controlling the operation of an electromagnetically operated contactor which shall be simple and eflicient in operation and which may be economically manufactured and installed.

A more specific object of our invention isto provide a thermally responsive device for controlling the opening of an electromagnetically actuated contactor.

Another object of our invention is to provide a device for automatically opening a contactor upon an overload condition and which may be remotely controlled by a manually operable switch connected to the device through a single conductor.

A further object of our invention is to provide for remotely controlling the reclosing of an electromagnetically actuated contactor after being opened by an overload condition.

Other objects of our fully hereinafter or skilled in the art.

In accordance with our invention, a main contactor, a thermally responsive tripping means, a control switch and trip resistors are mounted on a common base. The operation of the contactor may be controlled by means of a manually operable switch located remotely from the unit assembly. This switch has an overload trip which is actuated as the result of the operation will be apparent to those of the control switch by the thermal element to connect the trip resistors in the circuit for the overload trip, thereby preventing the automatic reclosing of the contactor after being opened by the thermal element.

For a better understanding of the nature and objects of our invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figurev 1 is a view, in top plan, of a contactor and control unit assembly embodying the principalfeatures of the invention, part of the cover for the unit being broken away;

Fig 2 is a view, partly in side elevation and partly in section, of the unit shown in Fig. 1

Fig. 3 is a view, in bottom plan, of the unit shown in Fig. 1;

Fig-.4 is a view, in section, taken along thelineIVt-IVof Fig. 3, and

invention will be explained itherein comprises an insulating base in Fig. 4, a cover plate 24 and a movable. core Fig. 5 isa diagrammatic view showing the con,-

associated apparatus.

Referring to the drawings, the structure shown upon which is mounted an electromagnetic contactor l l, a control switch 12 and a, pair of resistors l3. A recess I4 is base In in which is mounted a bimetal plate l 5 As shown most clearly in Fig. 2, a cover 18 may beattached to the base [0 by means of screws 19' which are threaded into brackets H on the cover [8. The cover #8 protects the contactor H, the, control switch [2 and the resistors [3. As shown 22 may be attached to the. bottom of the base It] to protect the bimetal plate, [5.

As shown most clearly in Figs. 1 and 2, the contactor H comprises a U-shaped frame 23, a coil,

25 which is disposed, inside of the coil 24. Contact bars 25 and 2? are attached to an insulating member 28 by bolts 29. The member 28 is attached to one end of the. frameZS by means of a metal plate 3! and screws. 32.

A bridging contact member is disposed to engage contact members 36 and 37 mounted on the contact bars 26 and 2-1, respectively. An arc -v ing contact member 38 is disposed to bridge con tact members 39 and 4| also mounted on the. contact bars 26 and 21, respectively.

As shown most clearly in Fig. 1, the bridging contact member 35 and the arcing contact mem.-, ber 38 are carried by the movable core 25. A compression spring 42 is disposed between the insulatin member 28 and the bridging contact member 35. Another compression spring 43 is disposed between the arcing contact member 3 8 and a cup washer 44 attached to the end of the core 25. A guide bar 45 is disposed to guide the movement of the bridging member 35 and the arcing contact member 38 as the core 25 is drawn into the coil 24 whenit is energized, thereby clos ing the bridging contact members and the arcing contact members.

The control switch l2 may be of a type well known in the art and is a single pole double; throw switch having a snap action with automatic return. The control switch may be attached to the base Ill by means of a U-shaped, bracket 46 andscrews 41.

As shown mostv clearly in Fig. 4, the controi switch has an actuating plunger 48 which actuates a contact arm 48. The contact arm 49 is sobia sed by a spring 50 that it returns to its normal; pe

provided in the bottom side of the.

sition, as shown in the drawings, when pressure is removed from the plunger 48. Terminal members 52 and 53 are provided on the control switch [2 for making the necessary electrical connections.

The resistors i3 are also of a standard construction. Terminal members 54 are provided on the resistors for makingelectrical connections to the resistors. Main contact studs 55 and 56 are provided for making the main circuit connections to the control unit. Secondary contact studs 58 are provided for making the control connections to the unit.

As explained hereinbefore, our invention provides for causing operation of the contactor H in response to overloads in the circuit controlled by the contactor. The bimetal plate i5 is utilized in controlling the operation of the contactor ll.

As shown most clearly in Fig. 3, the bimetal plate i5 is of a triangular shape. The base of the plate i5 is rigidly attached to the insulating base It by screws 55 and the bimetal is electrically connected in series with the main circuit which is controlled by the contactor ii. The remainder of the bimetal plate 45 is mechanically free and will deflect a certain amount corresponding to the temperature rise in the bimetal, which rise in temperature takes place when there is an increase in the amount of current flowing in the power circuit and through the bimetal plate. The free end of the bimetal is provided with an adjustable screw 62 which is disposed to engage the lower end of the plunger 48 for the control switch 82. It will be understood that the bimetal may be heated by a resistor connected in the main circuit if it is so desired. However, the structure may be simplified by connecting the bimetal directly in the main circuit as shown in the drawings.

As shown in Fig. 5, a switch 65, which is manually operable to open and close its contacts, is located remotely from the control unit assembly. The switch 55 is preferably a thermal circuit breaker having a thermally operated tripping mechanism comprising a bimetal 86 which bridges contact members 6? and 53 when a handle 59 is actuated to the closed position. The handle at is biased to the open position, as shown in the drawings, by a spring H. The bimetal 65 is biased to the position shown in the drawings by a spring 52. The circuit breaker is so constructed that when a predetermined current flows through the bimetal 6% it is actuated to interrupt the circuit through the contact members 5? and 68 and to permit the handle 69 to be returned to the open position by the spring H.

Referring to Fig. 5, it will be seen that when the circuit breaker 65 is closed to bridge the contact members El and 68 a circuit extends from positive through the contact members 6? and 68, conductor '55, contact members 59 and '56 of the control switch iii, the conductor H, the actuating coil 2 of the contactor H and conductor 13 to ground. The energization of the coil 2% closes the contact members of the contactor ll, thereby connecting the bimetal plate 55 in seriescircuit relation with the load circuit which is connected to the terminals 55 and 56.

Upon any fault or overload condition sufiicient to actuate the bimetal plate 55 the contact member 49 of the control switch 12 is disengaged from the contact member 36 and engages a contact member 19. This operation of the control switch i2 deenergizes the coil 2A of the contactor H, thereby opening the circuit through the contact members of the contactor. The operation of the switch 12 also establishes a circuit through the resistors [3. The establishment of the circuit through the resistors 13 causes suficient current to flow through the bimetal 66 of the circuit breaker 65 to operate the circuit breaker to interrupt the control circuit.

When the bimetal plate [5 cools down following the opening of the main power circuit by the operation of the contactor il, the contact member d9 of the control switch 52 is automatically returned to its normal position. However, the contactor ii is not reclosed since the circuit breaker 65 has been tripped and it must be reclosed manually in order to reclose the contactor I i. In this manner the contactor i i is automatically opened by an overload condition but it must be manually reclosed following the clearing of the overload or fault condition. It will be noted that only one wire is required between the circuit breaker S5 and the control unit which is located remotely from the circuit breaker.

From the foregoing description it is apparent that we have provided for controlling the operation of an electromagnetically actuated contactor or circuit breaker in a simple and efficient manner. The device herein disclosed provides for automatically opening the contactor upon an overload or fault condition and requires that the ccntactor be manually reclosed upon the clearance of the fault condition. The device is simple in construction and light in weight, thereby making it particularly suitable for utilization on aircraft. Furthermore, the amount of wiring connections is reduced to a minimum.

Since numerous changes may be made in the above described construction and difierent embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch having a normally closed contact connected in series with said coil and a second contact connected to an alternative circuit, a remote circuit breaker connected to the control switch for completing an energizing circuit for the coil, said circuit breaker including means for tripping the breaker in response to excess current, and means for actuating the control switch in response to excessive current in the load circuit to cause the control switch to open said normally closed contact to deenergize the coil and to close said second contact to complete the alternative circuit to the circuit breaker to effect tripping of the breaker.

2. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch having a normally closed contact connected in series with said coil and a second contact connected to an alternative circuit, a remote circuit breaker connected to the control switch for completing an energizing circuit for the coil, said circuit breaker in: cluding means for tripping the breaker in response to excess current, and thermally-responsive means heated by the current in the load circuit for actuating the control switch in response to excess current to cause the control switch to open said normally closed contact to deenergize the coil and to close said second contact to com- D plete the alternative circuit to the circuit breaker to efiect tripping of the breaker.

3. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch having a normally closed contact connected to said coil and a second contact connected to a resistor, means for connecting the coil and resistor to a source of electrical energy, a remote circuit breaker connected to said control switch for completing a circuit to said source for energizing the coil, said circuit breaker including means for tripping the breaker in response to excess current, and means responsive to excessive current in the load circuit for actuating the control switch to open said normally closed contact to deenergize the coil and to close said second contact to complete an alternative circuit including the resistor to effect tripping of the circuit breaker.

4. A control device comprising a contactor for controlling a load circuit, said contactor having an operating coil, a control switch having a normally closed contact connected to said coil and a second contact connected to a resistor, means for connecting the coil and resistor to a source of electrical energy, a remote circuit breaker connected to said control switch for completin a circuit to said source for energizing the coil, said circuit breaker including means for tripping the breaker in response to excess current, and thermally-responsive means heated by the current in the load circuit for actuating the control switch in response to excessive current to open said normally closed contact t deenergize the coil and to close said second contact to complete an alternative circuit including the resistor to eifect tripping of the circuit breaker.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,816,942 Trent Aug. 4, 1931 1,871,875 Bradford Aug. 16, 1932 1,986,445 Parsons Jan. 1, 1935 2,307,776 Grant Jan. 12, 1943 2,384,372 Eaton Sept. 4, 1945 2,539,206 Robinson Jan. 23, 1951

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