US1349361A - Furnace-regulator system - Google Patents

Description

E. M. BOUTON.

FURNACE REGULATOR SYSTEM. APPHCATION FILED APR. 9. 919.

1,349,361 Patented Aug. 10, 1920.

2 SHEETS-SHEET I.

INVENTOR Edy ar M 500760.

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UNITED STATES EDGAR M. BOUTON, OF WILKINSBURG, PENN PATENT OFFICE.

FURNACE-REGULATOR SYSTEM.

To all whom it may concern:

Be it known that I, EDGAR M. Bou'roN, a citizen of the United States, and a resident of Wilkinsbur in the county of Allegheny and Stateof l ennsylvania, have invented a new and useful Improvement, in Furnace- Regulator Systems, of which thefollowing is a specificatiorc. v a

My invention relates to retgulator systems and particularly to systems or maintain' substantially constant current-flow throng electric furnaces.

One object of roy inventionlis to provide :a furnace-regulator s stem ,of, the above-indicated character jt at shall automatically maintain a substantially constant current flow through the furnace in a simple and economical manner under .variable-loadicou substantially free from any socalled hunting action and rotect the furnace against any abnorma circuit conditions. 4 a i f In electric furnaces, and particularl in electric furnaces provided with resistors aving negative temperature coefficients, it is essential that the current-flowthrough the furnace shall be maintained substantially constant in order to prevent ,subjection of the material being treated to abnormal temperature conditions." Moreover, K't desirable to so operate; the furnace automaticallythat constant supervision of, and-attention to, it shall not be necessary. I

In a furnace regulator constructed in accordance with my invention, the currentflow through the furnace resistor ismaintuine d substantially constant by automatically varying the voltage of the currentsupplied to the furnace in accordance with the current flowing through the furnace resistor. =Moreover, automatic means is pro vided for preventing an abnormal currentfiow through the furnace resistor and for preventing the operation of the furnace in case the furnace. resistor has been heated above a predetermined temperature.

In the furnace system vutilized for describing my invention, a transformer, havin an adyustable primar winding and a secon ary winding, is provi ed for connectin a heatin resistor to a supply circuit. .series with the secondary-winding of the furnace resistor a plurality of current relays, which are selectively operated by the current flowing through the furnace resistor, are pro- I Specification of Lctters Pat ent. Patented A 10 1920 Application filed April 9,

1919. Serial No. 288,678.

vided for operating a plurality of auxiliary relays. The current relays are relatively slow acting andare prevented from chattering by any suitable means, such, for example, as dash pots connectedto their core armatures, andthea'uxiliary relays-are provided with holdin circuits which are closed on operation .0 the relays andwhich are under the control of the current rela s. Thus, upon releaseof a current relay, t e circuit of the auxiliary relay associated with it is opened. The auxiliaryirelays control aplurahty of .switches which vary the number-of effective .turns included-ingthe primarywinding of jthe transformer and thus regulate the current flow through the. furnace resistor.

.Moreover, if .so desired, the furnace resistor may be protected against an abnormal current-flow through it, and means ma be provided for preventing the closing-o the cir cult of the furnace'resistor in case-the resistor is heated above a predetermined tempera'ture.

. In the accompanyingdrawings, Figure] is a diagrammatic view of a furnace regu lator systemembodying my invention, and Fig. 2 is a regulator system similar to the system illustrated in- Fig. 1 and provided with additional rotective means.

Referring to ig. llof the drawings, an electric furnace 1, provided with a resistor 2 preferably having a negative temperature coefficient, is adapted to be connected across a supply circuit comprising conductors 3 and 4, by means o a transformer 5. The transformer 5 embodies-a secondary winding (3, which is connected in circuit withthe furnace resistor 2rand a primary winding 7, which is provided with a plurality of taps 8, 9, l0 and 11 extendingfrom it. The tap .or terminal 11 ispreferably directly connect- .ed to thesupply conductor 3, and the taps 8, 9. and 10 are selectively connected to the supply conductor 4,-as will be hereinafter set forth, for regulating the current-flow through the furnace resistor 2.

Two current relays 12 and 13 are operated in accordance with the current flowing through the furnace resistor 2 and serve to govern the operation of two auxiliary relays 14 and 15. The current relays 12 and 13 res ectively embody energizing coils 16 and 1?, which are dividedhinto parts 16"- and 16 and 17" and 17", core armatures 18 and 19, which are provided with dash pots SYLVANIA, ASSIGNOR TO WESTINGHOUSE upon 20 and 21, and switch members 22 and 23.

.The witch member 22 is adapted to bridge either the contact members 24 or the contact members 25, according to the operative position of the relay l2, and the switch member 23 is adapted to bridge the contact members 26 or the contact members 27, ac cording to the operative position of the relay 13. The current relays, being operated b alternatin currents, are inclined to c iatter so'mew at; but, by reason of the fact that it takes less current to hold a relay in an operative position than to operate it and by reason of the slow action caused by the dash pots, they are held in operative position sufiiciently to effect operation of the auxiliary relays.

A two-pole, double-throw switch 28 is provided for selectively connecting the energizing windings 16 and 17 of the relays 12 and 13 in circuit with the furnace resistor 2. The switch 28 embodies two knife-blade membars 29 and 30 which are connected to two contact terminals 31 and 32 when it is desired to connect only the portions 16 and 17 of the windings 16 and 17 in circuit.

with the resistor 2 and thus operate the furnace at a high temperature. The knife blades 29'and 30 are also adapted to enga e two contact terminals 33 and 34 when it is desired to connect the complete windings 16 and 17 in circuit with the resistor 2 and thus operate the furnace at a lower temperature.

The auxiliary relay l4 embodiesa'n energizing winding 35 which is connected across the supply conductors 3 and 4 upon bridging of the contact terminals 25 by means of the switch member 22 when the relay 12 is operated. -The auxiliary relay 14 is further provided with'a core armature 36, which, operation, engages an interlock switch member 37'to complete a holding circuit from the supply conductors B and 4 through a resistor 37 and the winding 35 of the relay. The core armature 36 is further connected to a switch member 38 which an gages the contact terminal 39 when the re lay is in a rele'a'sed position and engages a contact terminal 40when the relay is in an energized position.

The auxiliary relay 15 embodies an energizing winding 41 which is connected'ac ross the supply conductors 3 and 4 upon bridging of the contact terminals 27by the'switch member 23 when the'current relay 13 is opperated. The winding 41 operates on a core armature 42 which operates two contact "members 43 and 44. The switch member 43 engages a contact terminal 45 upon operation of the auxiliary relay to complete a holding circuit from the supply conductors 3 and 4 through a resistor 46 for maintaining theauxiliary relay 15 in an operative position until the switch member 23 e'comes disengaged from the contact terminal 27 and is connected across the supply conductors 3 and 4 when the contact members 38 and 44 respectively engage contact terminals 39 and 47. As'witch member 54 is-operated by the winding 53 for bridging contact terminals 55 to connect the transformertap 10 to the supply conductor 4. The switch 51 embodies a winding 56 which is'connected across the 'supplyconductors ifl and 4 when the switch member 38 engages the contact terminal 40. The winding 56 operates a switch member '57 to bridge'cohtact terminals 58 and connect'the transformertap 9 to the supply conductor 4. The switch 52 embodies a winding'59, which is connected across the supply. conductors 3and 4 when the switch member 44 ofthe auxiliary relay 15 is in engagement with the contact terminal 48. The winding -5'9operates a switch member 60 which bridges contact terminals 61 for connecting the transformer tap 8 to the supply conductor 4.

Assuming the various parts of the system to be in the position shown and the switch 28 'to be operated so that the knife blades 29 and 30 engage the contact terminals'3l and 32, then a circu t-is completed from the supply conductor 3 throu h the switch member 44, contact terminal 4 switch member 38, contact terminal 39 and winding 53 of the switch 50 to the supply conductor 4. Thereupon, the switch'50 is operated and a circuit is com leted from the supply conductor 4, throug the contact terminals 55-which are bridged by the switch member 54 of the switch 50'transformer tap 10 and the secondary winding 7 to the supplv conductor 8. The transformer 5 is energize anda circuit is completed through the furnaceresistor 2 which is traced from one terminal of the secondary winding 6, through the resistor 2, winding 16 of the current relay 12, contact terminal 32, knife blade 30. windin 17 of the current relay 13, contact termina 31 and the knife blade 29 to the other terminal of the secondary windingfi.

The current relays 12 and 13 are set to be operated at different current values, the relay 12 operating at one current value and the relay 13 operating at a somewhat higher current value. .Thus, in case the currentflow through theresistor 2 is raised above a' ductors 3 and 4 through the the auxiliary re 33 14. The auxiliar age of the current which is supplied to the transformer 5. Upon operation of the current relay 12, the switch member 22 becomes disen aged from the contact terminals- 24 and bridges the contact terminals 25 to complete a circuit from the su ply coning of relay 14 is operated an a holding circuit t erefor is established by the interlock switch '37. The holding circuit is traced from supply conductor 3, through the resistor 37, interlock switch 37 and the windin 35 to the supply conductor 4. The switc -member 38, upon operation of the auxiliary relay 14, becomes disengaged from the contact terminal 39 and engages the contact terminal 40and thus releases the switch and completes a circuit through thewinding 56 of the switch51. The circuit through the winding 56 is traced from the supp1y1co'n- .ductor 3, through the switch member 44,

contact terminal47, switch member:38, coiltact terminal40 and the winding 56 'to-athe supply conductor 4. Upon release ofthe switch 50, the transformer tap IOziS disconnected from the supply conductor'.4 =a.nd, upon operation of the switch 51, the transformer tap 9 is connected to the suppl' conductor 4. Thus, the number of I e ective turns in the primary winding 7 of the transformer 5 has been increased, and accordingl the voltage supplied to the secondary -WlIl ing 6 is so reduced as to reduce the current flow through the resistor '2.

In case the lowering of the voltage supplied to the secondary windin 6 b the increasedtnumber of turns inc ude -in the primary winding does-'not reduce the secondary current and such current isiraised by furnace conditions to a second predetermined value, then the current relay 13 is operated to further reduce the voltage impressed upon the secondary winding 6.

Upon operation of the current relay 13 the switch member 23 becomes disengage from contact terminals 26 and bridges the contact terminals 27 to connect the -energizing winding 41 of'theauxiliary relay 15 across the supply conductors 3- and 4. The auxiliaryrelay 15 is operated and a holding circuit therefor is completed by'the interlockswitch 43. The, holding circuit is traced from the supply conductor 3 through the resistor 46, contact terminal 45, contact member 43 and the winding '41 to the supply conductor 4. The switch member 44, upon operation of the relay, becomes disengaged from the contact terminal 47 and engages contact terminal 48 to release the swltch 51 and complete a circuit through the winding 59 of the switch 52. The] switch 51 disconnects the transformer tap 9, -from the supply conductor 4 and the .switchi52 connectsthe transformer tap 8 to the sup "are each in an operative current-flow through the reduced tof' such 5 point as'to release the current'rel'ay 13, then the switch member 23 ply conductor 4, thus, the number of effective turns included in the primary winding 7 have been increased and the voltage impressed upon the secondary winding 6 has been reduced.

In describing my invention, only two current relays 12 and 13 and a corresponding number of auxiliary relays have been illustrated but it is to be understood that, if so desired, the number of current relays and the resistorhaving a negative temperature coefiicie'nt; v e V I In-case thetwo current relays 12 and '13 urnace resistor 2 becomes disengaged from thecontact terminals 27 and bridges the contact terminals '26. Thereupon, the:winding 41 of the auxiliary relay 15 is short-circuited to effect the release of the relay15. Consequently, the holding circuit through the winding41 is broken, and the switch member 44 opens the circuit through the circuit 59 of the switch 52 and completes a circuit through 100 the winding 56 of the switch 51. Thus, the switch 52 is released to disconnect the transformer tap 8 from the supply con- -ductor 4, and the switch 51 is operated to 9 to the supply 1 connect a transformer. tap

conductor 4. Consequently, the number of efi'ective turns included in the transformer winding 7 is reduced and the voltage impressed upon the secondary winding Gis increased to effect a correspondingincrease in 110 the current-flow through the resistor'2. Assum1ng a; furtherreduction in the current-flow. through the furnace resistor 2, the current relay 12 is released, and the switch member 22 becomes disengaged from the 1 5 contact terminals 25 and bridges the contact terminals 24. Thereupon, the winding 35 of the auxiliary relay 14 is short-circuited to release the relay. The interlock switch 37 opens the holding circuit through 1 the winding 35, and the switch member 38 becomes disengaged from the contact terminal 40 and engages the contact terminal 39 to release the switch 51 and operate the switch 50. disconnected ;from the supply conductor 4 and the transformer tap 10 is connected to the supply conductor 4. Consequently, the

number of efiective turns included in the primary winding 7 is further reduced to in- 180 osition, and the Thus, thetransformer tap 9 is 25 crease the voltage impressed upon the secondary winding 6 and, accordingly, to increase the current flow through 'the resistor 2.

In case the switch 28 is thrown to its reverse position to connect the switch blades 29 and 30 to the contact terminals 33 and 34, then the complete windings 16 and 17 of the curent relays 12 and 13 are included in circuit with the furnace resistor 2. Consequently, the relays 12 and 13 will be operated at lower current values in order to reduce the current flow which is maintained in the furnace.

In Fig. 2, a system is disclosed which is similar to the system disclosed in Fig. 1 with the exception that certain additional protective means are provided for insuring the furnace against damage by reason of an excessive current-flow through it or overheating by reason of continued operation at too high temperature. In the system shown in Fig. 2, like parts to those shown in Fig. 1 are indicated by similar reference characters, and only so much of the system shown in Fig. 2 as differs from the system shown in Fig. 1 will be described in detail.

Referring to Fig. 2, a no-volta e relay 80 leased, it is impossi le toagain start the is provided for governing t e circuit through the switch members '44 and '38, which effects the operation of the switch 50 to connect the transformer 5 across the supply conductors 3 and 4. The relay 80 embodies a winding 81 which is initially connected across the supply conductors 3 and 4 by means of a thermal device 82 and which is provided with a holding circuit through an overload relay 83. The winding 81 controls a switch member 84 for the purpose above set forth. The overload relay 85. which is connected in series with thesecondary winding 6 and the furnace resistor 2. The winding 85 controls a switch member 86 which connects the winding 81 of the no-voltage relay 80 through the switch member 84 across the supply conductors 3 and 4. The thermal device 82 embodies a heating coil 87 which is included in series with the furnace resistor 2, and a switch member 88, which is normally adapted to complete a circuit from the supply conductors 3 and 4 throu h the energizlng winding 81 of the no-vo tage relay 80. The thermal device 82 is completelIyI described in a copending application of enry D. James, Serial No. 308,723, filed July 5, 1919. and, accordingly, a detailed explanation thereof is deemed unnecessary in this application. It may be noted, however, that, upon'excessive heating of the coil 87, the switch 88 is opened and will not be closed again until the heating coil 87 has been cooled to a predetermined point.

Assuming the parts ofthe system shown in Fig.- 2 to be in the position illustrated, a circuit is completed from the-supply con doctor/1:, through the winding 81 of the no lays 12- and 13, the-auxiliary relays 14 and l5and the switches 50, 51nand 52 issimilar to rtheroperation-of those parts as set forth in describing; Fig. 1 1. r

Incase' arr-excessive current-allow passes thnough I the 1 circuit including the secondary wiindingvfi .and'the furnace resistor2,

then the overload relay 83 isoperated to break -the;;holdingeircuit of the no-voltage relay 80,*thereupqnl the no-voltage relay 80 is released and, accordingly, the transformer-5 is disconnected from the supply circuit to deenergize the furnace.

"When the no-volta "relay 80 has been refurnace until the circuit of the=energizing winding 81 for the no-voltage relay iscom- 'pleited -t'hrough the v thermal device 62.

Thus, in case-thefurnace has been operated at an excessively high: temperature, it will he impossible to again connect the" transformer "5 across the "supply conductors 3 and until the heating coil 87 of the thermal device '821has'been cooled to such point as will permitthe closing of 'theswitch 88 v and thefconsequent operation of chemo-volt- 83 embodies a winding agglrela 80 i odi cations in the system and in the arrangement'and location of parts may be made within the spirit and scope of my invention 'and such modifications are intended to be co vered"by the appended claims.

l I' claim as my invention 1.111 a 'furnaoe regulator system, an electric furnace, a" transformer for connecting the furnace to a supply circuit, and means controlled by the yal'ue of the current flowing' through the furnace for automatically varying the "effective turns of said trans former to maintain a substantially constant current-flow through the furnace.

2. In a furnace-regulator system, a transformer havin a primar and a secondary winding, a urn'ace'res1stor connected in circuit with said secondary windin and 'means controlled by the current owing through the secondary winding for varying the number of efit'e'ctive turns in the primary winding of the transformer.

"3. In a furnace-regulator system, a transnace resistor, a supply circuit, means comprising a no-voltage relay for connecting said resistor to the supply circuit, an overload relay for deenergizin the no-voltage relay in case the current ow through the resistor is raised above a predetermined value, and means, comprising a thermal device, for effecting an initial operation of the no-voltage relay and for preventing the operation of the no-voltage relay under certain thermal conditions of the resistor.

15. In a furnace-regulator system, a furnace resistor, a supply circuit, meanscomprising a no-voltage relay for connecting said resistor to the supply circuit, an overload relay for denergizing said no-voltage relay under certain circuit conditions and ham an energizing winding controlled in accor ance with the operative position of said -no-voltage relay, and a thermal device for preventing the operation of the no voltage relay under certain conditions.

16. In a. furnacerregulator system, the combination with a supply circuit, a transformer having a primary and a secondary winding, and a furnace resistor connected in circuit with said secondary winding, of

a no-voltage relay for connecting said transformer across the supply circuit, means controlled by said no-voltage relay for varying the number of effective turns in said rimary winding to govern the current- 0W throu h said resistor, an overload relay controlled by said no-voltage relay and serving to open the circuit of the resistor under certain circuit conditions, ,and .thermal means controlled by the current flow through said resistor for preventing the operation of said no-voltage relay under certain circuit conditions.

17 In an electrical heatin system, the combination with a variable source of energy and a heating element having a negative temperature-resistance coeflicient adapted to be energized from said source of energy, of means comprising plural-position switches for selectively varyin the efi'ec t of said source of energy on sai heating elementa In testimpny whereof, I have hereunto subscribed myrname this 29thday of March lgl9h if i V

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