US1964374A - System of electric distribution - Google Patents

Description

" June 26,1934. w s 1,964,374

SYSTEM OF ELECTRIC DISTRIBUTION Filed April 30, 1930 6 L/ .67 In ulahoq M 55 I /5 /4 Air-:- YR) MK 114mm 1 NvENToR ATTORNEY Patented June 26, 1934 UNITED STATES SYSTEM or ELECTRIC DISTRIBUTION Herbert K. William's, Newark, N. J., assignor to The Safety Car Heating & Lighting Company, a corporation of New Jersey Application April 30, 1930, Serial No. 448,589

25 Claims (Cl. I'll- 313) This invention relates to electrical systems of distribution and more particularly to the regulation thereof.

One of the objects of this invention is to prop, vide a simple, thoroughly practical and reliable proper operation arising out of otherwise uncontrollable defects in certain parts of the equip-.

ment. Another object is to provide a regulating apparatus in which undesired changes in the standard of regulation, such as might be caused by failure of, or defects in, certain parts of the apparatus, are prevented in a thoroughly practical, efficient and reliable manner. Another object is to provide a regulating apparatus of the above-mentioned character in which changes in the standard of regulation, due to changes in temperature of the controlling parts, are effectively prevented and, more particularly, to provide simple and adequate safeguards against the failure, on the part of the temperature-compensat-ing device or devices, to achieve proper or intended functioning. Another object is to provide efiicient and dependable safeguards against overcharging of a storage battery in a car lighting system of the axle-driven generator type, and, particularly in car lighting systems of this type, to prevent over-charging of the storage battery as might result from unintended or accidental changes in the standard of regulation due to the failure of temperature-compensating resistances, associated with the regulating coil or coils, to perform their intended functions properly. Another object is to provide a system and apparatus of the above-mentioned character that will be well adapted to meet the varying conditions of hard practical use. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing the figure shows diagrammatically a preferred form of the various possible embodiments of my invention.

Referring now to the drawing, there is shown at 10 a generator, preferably a direct current generator and illustratively a generator driven from the axle of a railroad vehicle, connected through the main line conductors 11 and 12 to 6G a work circuit in which is included a storage battery 13 and lamps 14. The generator 10, which is thus intermittently operative and which operates at varying speeds, depending upon the speed of the car axle, has its connection to the work circuit controlled by an automatic switch diagrammatically indicated at 15, this switch being of any suitable type or construction for automatically connecting the generator to the work circuit when the voltage thereof has risen suf- 7 ficiently to commence charging of the storage battery 13 and to disconnect the generator from the work circuit when the voltage of the generator, due to a drop in speed thereof, diminishes to a value insufficient to supply energy to the work circuit.

The storage battery 13, maintained in a charged condition by generator 10, serves to supply energy to the lamps 14 when the generator is at rest or is operating at too low a speed. Any suitable form of regulating device, diagrammatically indicated at 16 in the form of a carbon pile regulator, may be interposed between the battery 13 and the lamps 14 for preventing the voltage across the lamps 14 from exceeding a certain value appropriate for operating the lamps or other translation devices.

The output of the generator 10 is regulated as against speed changes thereof and also with regard to the protection of the storage battery 13 against over-charge. Illustratively the regulating means preferably includes a variable resistance preferably in the form of a compressible carbon pile 17 connected in circuit with the shunt field winding 1.8 of the generator 10. A bell crank lever 19, pivoted at 20, varies the pressure and hence the resistance of the carbon pile 1'1 under the control of a solenoid 2122, the core 21 of which is connected to one end of the lever 19 and the winding or coil 22 of which is connected, in a manner described in detail hereinafter, to be responsive to the voltage across the generator 10; the solenoid acts in opposition to a spring 23, the latter being preferably adjustable.

The voltage-responsive coil 22, through the mechanism just described, may thus achieve a regulation of the voltage-of the generator 10, preventing the. voltage from exceeding a predetermined value which is preferably determined by the voltage of the battery 13 when the latter is fully charged, so that, when the voltage coil 22 comes into action, further rise in voltage of the generator necessary to continue the charge of the battery is prevented, the charging current is thus caused to taper off, and the battery substantially floats across the generator.

Preferably, also, the regulating apparatus includes a suitable arrangement for preventing the current output of the generator from exceeding a certain value, thus to prevent over-loading of the generator 10 and to prevent, also, an excessive charging rate of current flow to the battery. Preferably I provide a solenoid 24-25, the winding 24 being connected in the main line conductor 12 so as to be responsive to the current output of the generator 10, has its core connected to a lever 26, pivoted at 27, the lever 25 being provided with a suitable lug 28 adapted to interengage with a lug 29 on the lever 19 so that the solenoid 2425, acting in opposition to a spring 30, preferably adjustable, may operate upon the carbon pile 17 through the bell crank lever 19.

Thus, should the current output of the generator 1O tend to exceed a certain value, the solenoid 2 l-25 decreases the pressure on the carbon pile 17 so as to out down the current output of the generator and thus bring it back to normal.

As conducive to a clearer understanding of certain features of my invention, it might at this point be noted that the character of the regulating action achieved by the voltage responsive coil 22 is important, particularly in view of the action of this coil in achieving protection of the storage battery 13 against over-charge. To understand this action more clearly, it might first be assumed that the storage battery is in a state of relatively low charge and that the generator 10 is operating at a speed sumcient to achieve the closure of the automatic switch 15 and to charge the battery 13. The battery being in a relatively low state of charge, its voltage will be relatively low and the desired charging rate of the battery 13 may be maintained at a relatively low generator voltage. This relatively low generator voltage energizes the voltage coil 22 but the latter is so proportioned with respect to the spring 23 that it is not strong enough to control the pressure on the carbon pile 17; in fact, these parts are so proportioned and adjusted that the volage-responsive coil 22 will not overcome the force of the spring 23, necessary for it to manipulate the carbon pile 17, until the voltage of the generator has risen to a value corresponding substantially to that of the voltage of the battery when the latter is fully charged.

During this period of relative inactivity of the voltage coil 22, that is, during the period of charging of the battery, the current-responsive coil 24 is operative, however. to maintain the current output of the generator 10 substantially constant as against speed changes of the latter and, assuming that no lamps 14 are turned on, this constant current output of the generator 10 goes to charge the battery 13.

As the battery approaches full charge its back voltage increases relatively rapidly and, if the current output of the generator 10 is to be maintained constant under the control of the current responsive coil 24, the voltage of the generator correspondingly increases; this increase in generator voltage is permitted to take place until a voltage is achieved sufficient to bring the voltage coil 22 into regulating action, whereupon further increase in generator voltage is prevented and the charging current to the battery 13 tapers oil due to the steady increasing back voltage of the battery approaching the value or standard of voltage maintained constant by the voltage-responsive coil 22.

Thus the battery 13 is safeguarded, by the current responsive coil 24, against an excessive charging rate and is safeguarded, by the voltage responsive coil 22, against over-charge. The action of the voltage coil 22 should be relatively precise. For example, should the voltage coil 22 come into action at a higher voltage, the stopping of the charge to the battery may never take place or may be delayed to such an extent that the battery has suffered injury due to overcharge. On the other hand, the voltage coil 22 should not come into action at too low a voltage for then the charge to the battery would be stopped too soon and the supply of stored energy, available during periods of inoperativeness of the generator 10, for serving the lamps 14, would be insufficient.

In order to prevent changes in ohmic resistance of the voltage coil 22, due to temperature changes, from affecting the standard of operation of the voltage coil 22, the voltage coil 22 has included in its circuit a resistance element, one of which is shown at 31, having preferably a zero temperature coefficient and being of such a high ohmic value that the changes in resistance of the coil 22 itself, due to changes in temperature thereof, are substantially counteracted or negatived; in the above-mentioned specific illustrative arrangement, the change in ohmic resistance of the coil 22 due to a temperature change, which change in ohmic resistance might be a substantial fraction of the ohmic resistance of the coil 22 itself, is made negligible or inappreciable in that this otherwise great change is thus made to become an insignificant fraction of the sum total of the ohmic resistances of the coil 22 and of the temperature-compensating resistance 31. Thus the intended precision of action or the desired standard of operation of the voltage regulating coil 22 may be dependably maintained as against temperature effects.

The resistance unit 31, which may be of any suitable construction and is preferably in the form of a non-inductive winding of wire of a suitable metal, may, however, in practice, undergo otherwise uncontrollable changes in the ohmic value of its resistance or it may even become defective so as to cause an interruption in the circuit of the regulating coil 22. In the former case, assuming that a change in the ohmic resistance of the temperature counteracting resistance 31 has taken place, a change in the standard of regulation of the voltage coil 22 is at once brought about. For example, should the ohmic resistance of the unit 31 increase, the voltage regulating coil 22 will come into action at a correspondingly higher voltage, resulting, as above pointed out, in over-charge of the battery. In the other case, assuming, that the resistance unit 31 open-circuits itself, the circuit of the voltage coil 22 itself becomes opened and the battery is left entirely without protection against overcharge. To prevent such detrimental results is one of the dominant aims of this invention.

I accordingly provide a number of resistance units, all having preferably the same characteristics, and in the drawing I have shown, by way of illustration, two temperature counteracting resistances, namely, the above-mentioned device 31 and a preferably identical resistance unit 32. These resistance devices are controlled so that the failure of one of them to function in the desired or intended manner results in the prompt replacement or substitution thereof by another. This rearrangement of the resistance devices I accomplish preferably by means of a switching arrangement generally indicated at 33 under the control of a suitable electromagnetic means generally indicated at 34.

The above-mentioned switching means, which, in so far as its mechanical features are concerned, may take any suitable form, preferably takes the form of the so-called key type of switch, including a downwardly biased spring contact or switch member 35, normally held in electrical contact with a relatively fixed contact 36 and adapted, upon movement in upward direction to break contact with the contact 36 and to make contact with a relatively fixed contact 37.

The switch member 35, normally biased in a downward direction, as above noted, is movable in an upward direction by a pivoted armature 38 acting thereon through the bar or rod 39 of insulating material and coacting with a core 40 of an electromagnet having two windings 41 and 42. As soon as there is effective suflicient magnetic flux to pull the armature 38 to the left, as viewed in the drawing, the switch member 35 is moved upwardly to break the circuit in which the contact 36 is included and to make and maintain the newly established circuit in which the contact 3'7 is now included.

As above pointed out, the voltage responsive coil 22 has in circuit therewith the high-ohmic resistance unit 31 and, with the parts of the switching mechanism 3334 in the position shown in the drawing, the circuit of the voltageregulating coil 22 will be seen to be as follows: From one side of the generator 10, as from the main line conductor 11, thence by way of conductor 43 through coil 22, conductor 44, conductor 45, coil 41, conductor 46, resistance unit 31 (sectionalized as and for the purpose more clearly described hereinafter), conductor 51, contact 36, 7

switch member 35, conductor 47, and thence by way of conductor 48 back to the other side of the generator 10.

Winding or coil 42 of the electromagnetic control mechanism 34 is connected in series with the voltage responsive coil 22 and is thus shunted about the resistance 31 and coil 41; more specifically, conductor 49 connects one terminal of the coil 42 to conductor 44 and leads to one side of the coil 22, while conductor 50 connects the other terminal of coil 42 to conductor 47 which in turn, through conductor 48, leads to the other side of the generator 10.

The windings 41 and 42 are wound upon the core 40 so that, under the above-assumed relation of the parts, they produce fluxes, in the magnetic circuit of the device 34, which are opposite, and the coils 41 and 42 are moreover so proportioned with respect to each other that these fluxes are equal to each other so long as the ohmic resistance of the resistance device 31 (or of any section thereof) remains fixed. The armature 38 thus remains unactuated and the circuit of the regulating coil 22 and of the re-' sistance 31 remains closed at the switch contacts 35-36.

As soon, however, as the ohmic resistance of the device 31 changes, the flux of one coil exceeds that of the other, armature 38 is moved to the left, switch member 35 is raised to open the circuit of the coil 22 and resistance 31 at the contact 36 and to close a new circuit at contact 3'7, temperature-compensating resistance 32 being included in this new circuit.

The new circuit thus established cuts out coil 41 and is held closed by coil 42 and may be traced from one side of the generator 10, conductor 43, coil 22, conductor 44, conductor 56, temperature-compensating resistance 32, conductor 52, contact 37, switch member 35, conductor 4'7, and thence by way of conductor 48 back to the other side of the generator. Thus the defective resistance unit 31 is removed from the circuit of the regulating coil 22 and a new resistance unit 32 put in its place. A suitable signaling device, preferably taking the form of a high resistance lamp 53, is bridged across the resistance device 32 and becomes illuminated when the latter is put into circuit, thus to indicate which resistance device is in operation and to indicate that the device 31 is defective and should be removed from the apparatus and a new one put in its place.

Should the ohmic resistance of the device 31 increase for any reason, so as to cause the voltage regulating coil 22 to regulate at a higher standard of voltage than the standard of voltage at which the fluxes of coils 41 and 42 are equal and opposite, the flux of coil 42 preponderates over that of coil 41 and thus causes the operation of the switch member 35 in the manner and with the results above described. Similarly, should the resistance 31 become open-circuited within itself for any reason, the flux due to coil 41 becomes zero and the coil 42 is promptly effective to cause an actuation of the switch mechanism 33. 0f the device 31 diminish so as to cause the coil 22 to regulate at a lower standard of voltage, such a relative change in the currents flowing through the opposing coils 41 and 42 takes place that the flux of one coil preponderates over the flux of the other, resulting in the prompt actuation of the switch 33.

Thus the intended standard of regulation of. the voltage regulating coil 22 is positively maintained in spite of the fact that otherwise uncontrollable changes take place in the temperature-compensating resistance associated therewith.

The switch means 33 is held in actuated position by armature 38 which in turn is held in its actuated or left-hand position by the coil 42 which alone remains effective, once the switch means 33 has been moved upwardly. This because the circuit of coil 41 which, as above noted. is in series with the resistance 31, is interrupted at the switch contact 36. Thus coil 42, now unopposed by coil 41, dependably maintains closed the new circuit in which the new resistance unit 32 is included.

Should the resistance unit 31 be subsequently replaced by a new unit, the subsequent starting up of the apparatus, assuming the new unit to be in proper condition, will cause the energization of both coils 41 and 42 at fluxes equal and opposite so that the movable parts of the ap paratus 33-34 will assume the position shown in the drawing until such time as the intended operating characteristics of the new resistance unit 31 change.

As above noted the resistance device 31 is preferably sectionalized and illustratively I have shown the device as divided into two sections 31 and 31', by means of a tap 54 provided at an intermediate point therein. The other resistance device or devices 32 is similarly sec- 50 Similarly, should the ohmic resistance tionalized and illustratively is shown as made of two similar sections 32 and 32 the sectionalizing being achieved by means of a tap made at an intermediate point in the resistance 32. The purpose of thus sectionalizing the resistance is to make it possible to effect a change in the standard of regulation achieved by the regulating apparatus. For example, the number of cells of the battery 13 may be changed and hence the constancy of voltage to be maintained to stop the charge of the battery should be correspondingly changed. Or, by way of further example, if the battery is of the lead type a lower standard of voltage constancy must be maintained to stop the charge of the battery than is the case if the battery were changed to the Edison type for which the stop-charge or floating voltage is higher. By determining the number of sections of the temperature-compensating resistance that are to be included in the circuit of the voltage regulating coil 22, I may determine at will the standard of voltage constancy to be maintained.

As will be clear from the foregoing detailed description, both sections 31 and 31 of the resistance unit 31 were assumed to be operative and for these two sections, the two sections 32 and 32 of the other resistance device 32 were substituted upon the former becoming defective.

Assuming now, however, that it is desired to lower the standard of regulation, I out out one of the sections of the initially operative resistance unit 31 so as to lower the voltage that will be maintained constant by the regulating apparatus. This cutting out of a section of the resistance unit 31 I prefer to achieve by means of a switch-like member 57 pivoted to a binding post 58 and adapted to be swung into electrical contact with a binding post 59, the latter being provided with suitable clamping means to clamp the switch member 57 in position. The switch member 57 short-circuits or by-passes a section, such as the section 31 of the resistance 31 and, in accordance with certain features of my invention, the device 57 is also made effective to cut out a similar section, such as section 32 of the resistance unit 32, when the latter is substituted for the resistance unit 31. Thus, even though a number of resistance units are employed, any one of which may be made effective in the circuit of the regulating coil, only one standard-determining means (device 57) need be employed.

In order to make clear this latter feature of my invention, it may first be noted that the switching device 33 is provided with another switch member 60 connected, like the switch member 35, to the insulating rod 39 so that it is actuated at the same time that the switch member 35 is actuated. Coacting with the switch member 60 is a switch contact 61 with which the member 60 is normally in contact, and also a switch contact 62 into electrical connection with which the switch member 60 is moved when the switch device 3 is operated by the armature 38.

A conductor 63 connects the switch contact 61 to the tap 54 of the resistance 31 while a conductor 64 connects the upper switch contact 62 to the tap 55 of the resistance unit 32. A conductor 65 connects the switch member 60 to the binding post 59 with which the switch member 57 is adapted to coact.

Assuming now that section 31 of the resistance 31 is to be cut out so as to lower the standard of voltage regulation, switch member 57 is moved into a position to connect binding posts 58 and 59; the section 31* of the resistance 31 will then be short-circuited or by-passed by way of a circuit which may be traced as follows: From tap 54, conductor 63, switch contact 61, switch member 60, conductor 65, switch member 57 (in closed position), conductor 47, switch member 35, contact 36, conductor 51, and thus back to the left-hand terminal of section 31 The circuit of the voltage regulating coil 22 will thus have included in it only section 31 of the resistance. 31 and the corresponding circuit may be traced as follows: From one side of the generator 10, as from the main line conductor 11, conductor 43, coil 22, conductor 44, conductor 45, winding 41, conductor 46, section 31 of the resistance 31, tap 54, conductor 63, contact 61, switch member 60, conductor 65,

switch 57 (in closed position), conductor 48, and

thus back to the other side of the generator 10.

Should the ohmic resistance of the section 31 change for any reason or become open-circuited, the balanced flux condition achieved by windings 41 and 42 under this new standard of voltage regulation becomes disturbed so that armature 33 is moved to the left to actuate the switch means 33, moving the switch members 35 and 60 out of contact with their respective lower contacts 36 and 61, and moving and holding them in contact with their respective upper contacts 3? and 62.

This actuation of the switch means 33 is made to bring about a substitution of the section 32 of the resistance unit 32 for the defective section 31 of the resistance unit 31, and the new circuit of regulating coil 22 will be found to be as follows:-

From one side of generator 10, conductor 43, coil 22, conductor 44, conductor 56, section 32 of resistance 32, tap 55, conductor 64, switch contact 62, switch member 60, conductor 65, switch 57 (in closed position) and by way of conductor 48, back to the other side of generator 10. The

section 32 of the substituted resistance unit 32 is held by-passed or short-circuited by way of the following circuitz-From the tap 55, condoctor 64, contact 62, switch member 60, conductor 65, switch 57 (in closed position), con ductor 47, switch member 35, contact 37, conductor 52, to the left-hand side or terminal of the section 32.

Thus it will be noted that the same standarddetermining means 57 is made to function to cut out a similar section in the resistance units, irrespective of which resistance is placed in circuit by the automatic devices 3334, and the danger of having one resist-ance unit function to set one standard of regulation and another resistance unit set another standard of regulation is dependably avoided.

When the armature 38 is actuated as above de scribed, it is held in actuated position by coil 42 alone, the circuit of coil 41 having been interrupted at switch contact 61. Thus coil 42 dependably holds in circuit the section 32 of the resistance 32, at contact 62, switch member 60 being now at its uppermost position.

The signaling device 53 will be seen to be bridged across the section 32 of the resistance 32 and the lamp 53 becomes illuminated as soon as the automatic devices have substituted the resistance 32 or a section thereof in the circuit of the regulating coil 22.

It will thus be seen that there has been provided in this inventiona resistance and apparatus in which the various objects hereinabove noted, together with many thoroughly practical advantages, aresuccessfully achieved. It will be seen that the apparatus is of a thoroughly practical nature, is of dependable action, and well adapted to meet the conditions of hard practical use.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawing, is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a system of the character described, in combination, a variable speed generator, a storage battery to be charged thereby, means including a voltage responsive coil for preventing overcharge of said battery, a resistance device associated with said coil for counteracting temperature changes in the latter, a second resistance device, and means responsive to departurefrom normal temperature-counteracting condition of said first-mentioned resistance device even though the circuit of the latter remains intact for associating said second-mentioned resistance device with said coil in place of said first-mentioned resistance device.

2. In a system of the character described, in combination, a variable speed generator, a storage battery to be charged thereby, means including a voltage responsive coil for preventing overcharge of said battery, a resistance device associated with said coil for counteracting temperature changes in the latter, a second resistance device, switch means adapted upon operation to remove said first-mentioned resistance device from the circuit of said coil and to associate said secondmentioned resistance with said coil, and a pair of coils having opposing effects upon said switch means for actuating the latter, one of said coils being in series with said first-mentioned resistance device and the other of said coils being connected in shunt to said first-mentioned resistance device.

3. In a system of the character described, in combination, a variable speed generator, a storage battery to be charged thereby, means including a voltage responsive coil for preventing overcharge of said battery, a resistance device associated with said coil for counteracting temperature changes in the latter, a second resistance device, means responsive to change in the intended action of said first-mentioned resistance device for associating said second-mentioned resist. ance device with said coil in place of said firstmentioned resistance device, signaling means, and means responsive to said change-responsive means for controlling said signaling means to cause the latter to indicate which of said resistance devices is associated with said coil.

4. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, means adaptedwhen placed in circuit with said coil for counteracting the efiect of changes in temperature of the latter, a second temperature-eifect-counteracting means, switching means adapted in one position to associate one of said means with the circuit of said coil and in another position to associate the other of said means with the circuit of said coil, and electromagnetic means responsive to change in either direction in a function of the current supplied to said work circuit as caused by change in the condition of one of said counteracting means for moving said switching means from one position to the other.

5. Ina system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means inciuding a coil for controlling a function of the current supplied to said Work circuit, means adapted when placed in circuit with said coil for counteracting the effect of changes in temperature of the latter, a second temperature-effect-counteracting means, switching meansadapted in one position to associate one of said means with the circuit of said coil and in another position to associate the other of said means with the circuit of said coil, and means for actuating said switching means comprising a plurality of differential coils having equal effects, one of said coils being connected to respond to changes in a function of the current supplied to said Work circuit as caused by change in the operative condition of one of said counteracting means.

- 6. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, means for actuating said switching means, said actuating means including a coil connected in series with said connected resistance, and a coil shunted about said serially connected resistance and said second-mentioned coil.

7. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil,'and means for actuating said switching means, said means including a normally energized coil tending to actuate said switching means and a coil opposing said lastmentioned coil and connected to be responsive to a change in current in decreasing direction through said connected resistance.

8. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, and means responsive to changes in the standard of regulation achieved by said coil as a result of change in resistance of said connected resistance for actuating said switch.

9. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, means for actuating said switch and for holding it in its actuated position, and means for changing the effective ohmic value of said resistances to change the standard of regulation of said regulating means.

10. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current sups plied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, means for actuating said switch and for holding it in its actuated position, and a single means adapted in either position of said switch to change the ohmic value of the connected resistance for changing the standard of regulation of said regulating means.

11. In a system of the character described, in combination, a source of current, a. work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, means for shortcircuiting a portion of said connected resistance, thereby to change the standard of regulation of said regulating means when said switching means is in normal position, and means responsive to the actuation of said switching means for shortcircuiting a portion of the other resistance.

12. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, taps on said resistances for sectionalizing the latter, means operable at will for determining the number of sections that are to be operative in said connected resistance, and means responsive to the actuation of said switching means for causing a like number of sections of said second-mentioned resistance to be operative.

13. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, regulating means including a coil for controlling a function of the current supplied to said work circuit, a resistance for compensating for changes in temperature of said coil, a second compensating resistance, switching means normally connecting one of said resistances in circuit with said coil and adapted upon actuation to connect the other of said resistances in circuit with said coil, taps on said resistances for sectionalizing the latter, means operable at will for determining the number of sections that are to be operative in said connected resistance, and auxiliary contacts on said switching means connected between said determining means and the sections of said second resistance and adapted upon actuation of said switching means to make operative the same number of sections of said second resistance as were operative in said first resistance.

14. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, means for changing the standard of regulation of said regulating means, a second means for changing the standard of regulation of said regulating means, and means responsive to an abnormal change in either direction in standard of regulation caused by one of said standard-changing means for substituting therefor the other standard-changing means.

15. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, means for changing the standard of regulation of said regulating means, a second means for changing the standard of regulation of said regulating means, means for making either of said standard-changing means effective, a signaling device, means controlled by said last-mentioned means for causing said signaling device to indicate which of said means is effective.

16. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, means for counteracting the effect of changes in temperature of said regulating means, a second means adapted to counteract changes in temperature of said regulating means, means for making either of said counteracting means effective, signaling means, and means responsive to effective condition of the circuit of one of said counteracting means for making said signaling means effective.

17. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, means for counteracting the effect of changes in temperature of said regulating means, a second means adapted to counteract changes in temperature of said regulating means, means responsive to abnormal operation of one of said counteracting means for making the other counteracting means effective, signaling means, and means controlled by said responsive means for controlling said signaling means.

18. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, a resistance for affecting said regulating means, a second resistance adapted to affect said regulating means, switching means adapted upon operation to substitute one resistance for the other, and means for controlling said switching means including two differentially-acting windings, one of which is in series with said first-mentioned resistance and the other of which is in shunt relation to said first-mentioned resistance.

19. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, said regulating means including a winding, a resistance in circuit with said winding for affecting the standard of operation of the latter, a second resistance, switching means adapted upon operation to remove said first resistance from the circuit of said winding and to insert in said circuit said second resistance, and means for controlling said switching means including two coacting coils, one of which is in series with said first resistance and the other of which is in shunt relation to the latter.

20. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit,

said regulating means including a winding, a resistance in circuit with said winding for affecting the standard of operation of the latter, a second resistance, switching means adapted upon operation to remove said first resistance from the circuit of said winding and to insert in said circuit said second resistance, and means for controlling said switching means including two coacting coils, one of which is in series with said first resistance and the other of which is shunted about said serially connected coil and first resistance.

21. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, said regulating means including a winding responsive to said function of the current supplied to the work circuit, means for affecting the standard of operation of said winding, a second means adapted when made effective to affect the standard of operation of said winding, and means including a coil responsive to an unintended or abnormal value of the function of the current supplied to said work circuit for making said second standard-affecting means effective.

22. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, a resistance for affecting said regulating means, a second resistance adapted when made effective to affect said regulating means, electro-responsive signaling means related to said second resistance, and means responsive to departure from intended action of said first-mentioned resistance for making said second resistance and said electro-responsive signaling means effective.

23. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, a resistance for affecting said regulating means, a second resistance adapted when made effective to affect said regulating means, electro-responsive signaling means, switching means adapted in one position to cause said signaling means to give one indication and in another position to make said second resistance effective and to cause said signaling means to give another indication, and means responsive to departure from intended functioning of said first resistance for actuating said switching means from said one position to said other position.

24. In a system of the character described, in combination, a source of current, a Work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, a resistance for aifecting said regulating means, a second resistance adapted when made effective to affect said regulating means, electro-responsive signaling means in shunt relation to one of said resistances, thereby to be energized if said resistance is energized, and means responsive to departure from the intended functioning of said firstmentioned resistance for substituting said second resistance therefor.

25. In a system of the character described, in combination, a source of current, a work circuit supplied thereby, means for regulating a function of the current supplied to said work circuit, a resistance for affecting said regulating means, a second resistance adapted when made effective to affect said regulating means, electro-responsive signaling means in shunt relation to one of said resistances, thereby to be energized if said resistance is energized, switching means adapted in one position to make one resistance effective and in another position to make the other resistance effective, and means for controlling said switching means including a coil in series with the resistance that is initially effective and a coil in shunt relation to the said initially effective resistance.

HERBERT K. WILLIAMS.

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