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Publication numberUS2426906 A
Publication typeGrant
Publication dateSep 2, 1947
Filing dateJun 28, 1943
Priority dateJun 28, 1943
Publication numberUS 2426906 A, US 2426906A, US-A-2426906, US2426906 A, US2426906A
InventorsVaughan Victor G
Original AssigneeMetals & Controls Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Manual reset thermostatic switch in protective systems
US 2426906 A
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Description  (OCR text may contain errors)

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v. s VAUGHAN HANUAL RESET THERMOSTATIC SWITGE! IN PROTECTIVE SYSTEEBS Filed June 28, 1943:

FIG 2.

Patented Sept. 2, 1947 UNITED STATES ,iitstt MANUAL RESET THERMOSTATIC SWITCH IN PROTECTIVE SYSTEMS Victor G. Vaughan, Attleboro, Mass, assigncr to Metals & Controls Corporation,

Attleboro,

11 Claims. 1

This invention relates to electrical protective apparatus, and with regard to certain more we ciflc features, to thermostatically controlled protective means for electric motors and the like.

Among the several objects of the invention may be noted the provision of mechanically and elec trically simple protection apparatus for electrical energy translating devices (for example a motor or transformer) which allows manual reset means to be located at a distance from the protected apparatus while only small and compact parts are mounted on the casing of the protected apparatus. Other objects will be in part obvious and in part pointed out hereinafter.

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 the application of which will be indicated in the following claims.

In the accompanying drawing, in which are illustrated several of various possible embodiments of the invention,

Fig-l is a wiring diagram showing one form of the invention; and,

Fig. 2 is a wiring diagram showing a second form.

Similar reference characters indicate some sponding parts throughout the several views of the drawing.

Referring now more particularly to Fig. 1, there is shown at M a motor which is to be protected against overheating due either to overload or high ambient temperature. The circuit supplying the motor is shown at C. At numeral I is shown an automatic reset thermostatic protective assembly which it is intended shall be small enough to be mounted upon the motor casing, or at least be in the close vicinity of the motor so as to be responsive to ambient temperature conditions around the motor.

At 3 is shown a manual reset thermostatic assembly intended to be remotely located with respect to the motor.

Assembly I has main contacts 5 and 'l. Contact 5 is connected with the circuit C by wire Fl. Contact l is connected with a third contact H by way of a resistance heater l3 which is located closely adjacent to an automatic reset thermostatic element i5. The mechanical details of the thermostatic element I5 are shown in United States Patent 2,199,387. Thus i5 is a. bimetallic snap-acting thermostatic disc which upon temperature rise from normal temperature conditions snaps to an opposite curvature, thereby removing is reduced to normal.

' this time forms the contacts ii and it carried thereby from the tests 5 and i. Upon reduction in temper the disc l5 snaps baclc to the curvature shown to reclose contacts 5, it and l, ll. it is classified as an automatic reset thermostat.

The assembly ii is composed oi stationary con tacts 2E and 23 in a line and terminals and 29 between which is a resistance heater The contacts 2i and 29 are in a circuit; 33 which connects across the contacts 5 and "i in assembly 6.

A thermostatic disc of the snap-acting type carries movable contacts iii and St for opening and closing the contacts and in line The thermostatic disc 35 is oi. the so-cailed manual reset type, which i'ec'ioses only by manual operation of a reset button. i That is t s if the disc snaps to open position ups ing, it will remain in that position until manually, even though the temperature s n The details of a typical manual reset thermostat are disclosed in United States Patent 2,199,388.

Operation is as follows:

When the motor M is energized over the line C, current flows through the motor, line it, con tacts 5, iii, thermostatic disc 55, contacts resistance l3, line 2%, contacts disc contacts 31', 2| and back to the line C. No substantial current at this time flows through the resistance 3!, since there is very little potential. applied across this resistance, the resistance disc l5 being low.

If the motor becomes electrically overloaded, or overheated, the thermostatic disc it will re spond by snapping to reverse curvature and re move contacts ii, iii from contacts 5, i. i3 accelerates the heating of the disc l5. With open, current will thus be forced to flow from the line C through terminal 2], heater 3i, terminal 29, line 33, contact i, heater it, terminal ii. line 25, returning to the line C through the contacts 23, disc 35. contacts ill and iii, back to the line C. Heating of the disc 35 by the adjacent heater 3i causes the disc to'open. the line which at is ooiy connection closing the circuit C. Once disc snaps to open posi-- tion, it will remain there until reset by manual operation on the button iii. Thus even though disc it may reclose, a manual reclosure at is necessary.

From the above it will be seen that the of operation of the automatic reset disc open and shut the circuit across the re thus acting as a relay. Aite operated to break the circuit, :.l

3 that the automatic disc ll rec l oses the contacts Ii, l9 and I, I! because then the circuit C is in any event broken at contacts 2| and 2!.

Advantages of the invention are that the relay assembly I may be made small and sensitive and mounted on or near the motor while the assembly I may be made larger in its remote location.

At Fig. 2 is shown a form of the invention arranged so that the resistance l3 in the assembly I, when It is open, is not (as in Fig. 1) in series with the resistance II. To this end, the connection 33 and contact 29 are eliminated and the resistance II is connected between terminal 21 and contact 23 of the reset switch I. In this case, overload current first passes through connection 8, disc ll, heating resistance It, line 25, disc 35 and back to the line C. The heater It causes disc II to snap open initially, whereupon the circuit traces from line C to terminal 21 in assembly I, heater resistance 3|, disc 35 and back to the line C. The heater 3| then causes opening of the thermostatic element I5 which completely breaks tb motor circuit. This allows the automatic reset thermostat I to return to position prior to resetting the reset thermostat 8, without placing the motor back in the line.

It will be understood that the invention will provide protection for other translating or similar apparatus equivalent to the motor shown.

In view of the above, it will be seen that the several objects oi the invention 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 drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. Electrical protective means in a supply circuit, comprising a manual reset thermostat, an automatic reset thermostat, a heater element associated with each of said thermostats, a circuit placing the manual reset thermostat in series with the heater element of the automatic reset thermostat, means connecting the automatic reset thermostat so that when cold it shunts the heater element of the manual reset thermostat and when hot opens said shunt, and circuit means which places said heater element of the manual reset thermostat in series connection with said manual reset thermostat when said shunt is op n.

2. Electrical protective means in a supply circuit comprising a manual reset thermostat, an automatic reset thermostat, a heater element associated with each of said thermostats, a circuit placing the manual reset thermostat in series with the heater element of the automatic reset thermostat, means connecting the automatic reset thermostat, so that when cold it shunts the heater element of the manual reset thermostat and when hot opens said shunt, circuit means which places said heater element or the manual reset thermostat in series connection with said manual reset thermostat when said shunt is open, said last-named circuit means being arranged to connect both or said heater elements in series when said shunt is open.

3. Electrical protective means in a supply circuit comprising a manual reset thermostat, an automatic reset thermostat, a heater element associated with each of said thermostats, a circuit placing the manual reset thermostat in series with the heater element or the automatic reset thermostat, means connecting the automatic reset thermostat so that when cold it shunts the heater element of the manual reset thermostat and when hot opens said shunt, circuit means which places said heater element of the manual reset thermostat in series connection with said manual reset thermostat when said shunt is opened, said lastnamed circuit means being arranged to cut out of circuit the heater element of the automatic reset thermostat when said shunt is open.

4. In apparatus of the class described, an automatic reset thermostat assembly and a manual reset thermostat assembly, a thermostatic switch member and a heater in the automatic assembly and a thermostatic switch and a heater in the manual assembly, the thermostatic switch of the automatic assembly, its heater and the thermostatic switch of the manual assembly being normall in series, the thermostatic switch of the automatic assembly when closed shunting the heater of the manual assembly.

5. In apparatus of the class described, an automatic reset thermostat assembly and a manual reset thermostat assembly, a thermostatic switch member and a heater in the automatic assembly and a thermostatic switch and a heater in the manual assembly, the thermostaticswitch oi the automatic assembly, its heater and the thermostatic switch of the manual assembly being normally in series, the thermostatic switch of the automatic assembly when closed and its heater shunting the heater or the manual assembly,

6. In apparatus of the class described, an automatic reset thermostat assembly and a manual reset thermostat assembly, a thermostatic switch member and a heater in the automatic assembly and a thermostatic switch and a heater in the manual assembly, the thermostatic switch of the automatic assembly, its heater and the thermostatic switch or the manual assembl being normally in series, the thermostatic switch of the automatic assembly when closed shunting the heater of the manual assembly and said heaters being in series connection when the automatic reset thermostat is open.

7. In apparatus of the class described, an automatic reset thermostat assembly and a manual reset thermostat assembly, a thermostatic switch member and a heater in the automatic assembly and a thermostatic switch and a heater in the manual assembly, the thermostatic switch oi the automatic assembly, its heater and the thermostatic switch of the manual assembly being normally in series, the thermostatic switch of the automatic assembly when closed and its heater shunting the heater of the manual assembly and when the automatic reset thermostat is open said heater in the manual assembly being in series connection with the manual reset thermostat and the heater in the automatic assembly being disconnected.

8. In apparatus of the class described, an automatic reset thermostatic switch and a heater therefor, a manual reset thermostatic switch and a heater therefor, the automatic thermostatic switch, its heater and the manual thermostatic switch being normally in series, the automatic thermostatic switch when automatically closed shunting the heater oi the manual thermostatic switch, and means forming a series connection between the two heaters when the automatic thermostatic switch is open.

9. In apparatus or the class described, an automatic reset thermostatic switch and a heater therefor, a manual reset thermostatic switch and a heater therefor, the automatic thermostatic switch, its heater and the manual thermostatic cuit comprising a manual reset thermostat, an-

automatic reset thermostat, a heater element associated with each of said thermostats, a circuit placing the manual reset thermostat in series with the heater element of the automatic reset thermostat and with the automatic reset thermostat, means connecting the automatic reset thermostat so that when cold it shunts the heater element of the manual reset thermostat and when hot opens said shunt, and circuit means which places said heater element oi. the manual reset thermostat in series connection with said manual reset thermostat when said shunt is open. K

11. Electrical protective means in a supply circuit comprising a manual reset thermostat, an automatic reset thermostat, a heater element associated with each oi said thermostats, a circuit placing the manual reset thermostat in series with the heater element of the automatic reset thermostat and with the automatic reset thermostat, means connectinz the automatic reset thermostat so that when cold it and its heater shunt the heater element of the manual reset thermostat and when hot it opens said shunt, and circuit means which places said heater element of the manual reset thermostat in series connection with said manual reset thermostat when said shunt is open.

VICTOR G. VAUGHAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Weeks Jan. 23, 1945

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1700661 *Sep 11, 1925Jan 29, 1929Birka Regulator AbThermostatic control system for electric heat-producing apparatus
US1728038 *Aug 2, 1923Sep 10, 1929Gen ElectricAutomatic circuit controller
US1830578 *Dec 14, 1928Nov 3, 1931Westinghouse Electric & Mfg CoTemperature control system
US2063981 *May 19, 1934Dec 15, 1936Westinghouse Electric & Mfg CoProtective system for polyphase motors
US2313975 *May 23, 1939Mar 16, 1943Westinghouse Electric & Mfg CoElectric motor system
US2324161 *Mar 31, 1941Jul 13, 1943Honeywell Regulator CoControl means
US2367985 *Apr 16, 1942Jan 23, 1945Gen ElectricControl device
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2655621 *Oct 15, 1949Oct 13, 1953Westinghouse Electric CorpControl apparatus
US3113243 *Feb 9, 1959Dec 3, 1963Sta Rite Products IncOverload protection device
US3181037 *Feb 7, 1963Apr 27, 1965Int Standard Electric CorpConstant time delay circuit utilizing thermal delay switches connected in tandem
US3258647 *Jun 6, 1962Jun 28, 1966 Electrical apparatus
US3660793 *Apr 1, 1970May 2, 1972Therm O Disc IncThermostat with manual reset
US4758708 *Aug 4, 1986Jul 19, 1988Gte Products CorporationInsecticide dispenser with temperature sensor
Classifications
U.S. Classification361/105, 337/91, 236/68.00B, 219/511
International ClassificationH01H77/04, H01H77/00
Cooperative ClassificationH01H77/04
European ClassificationH01H77/04