US2052048A

US2052048A - Voltage regulator

Info

Publication number: US2052048A
Application number: US700813A
Authority: US
Inventors: Bennett M Leece
Original assignee: LEECE NEVILLE CO
Current assignee: LEECE NEVILLE CO
Priority date: 1933-12-04
Filing date: 1933-12-04
Publication date: 1936-08-25
Anticipated expiration: 1953-08-25

Description

Aug. 25, 1936.

B. M. LEECE VOLTAGEYREGULATOR Filed Dec. 4, 1933 illlll III Patented Aug. 25, 1936 UNITED STATES PATENT OFFICE VOLTAGE REGULATOR Bennett M. Leece, Cleveland, Ohio, assignor to The Leece-Neville Company, Cleveland, Ohio, at corporation of Ohio Application December 4,1933, Serial No. 790,813 14 Claims. (01. 171-229) This invention relates generally to voltage regulators and, more specifically, to an improved form of voltage regulating means which is suitable for use with a variable speed generator such as may be employed in a vehicle lighting and battery charging. system or in various. other types of generating systems. The invention relates further to a vibratory voltage regulator of the general type disposed in my prior Patent 1,540,698,

granted Jun: 2, 1925, but is an improvement over the device of this patent.

E-ieretoiore, in the construction of voltage regulating devices, it has been generally the custom to construct the regulator with its various parts, and particularly its regulating resistance, designed and proportioned in accordance with the characteristics and requirements of the particular generator with which the regulator is to be used. Regulators thus designed for use with particular generators have been more or less limited in application to motor vehicles in the truck and bus class, but a growing demand for voltage regulators in the passenger car class of vehicles has demonstrated the need for a regulator which, within a particular class of vehicles, will be'more or less generally applicable to diiierent, makes and types of generators.

It is, therefore, an object of the present inven- I tion to provide an improved form of regulating device, of the vibratory type, wherein a field regulating resistance is employed having a relatively high temperature coeflicient so that the device will be self-adjusting and, therefore, selfaccommodating to the varying characteristics of the different types of generators to which the device may be applied.

Another object of the invention is to provide an improved regulator of the type mentioned em-" voltage of the generator whereby the regulator is self-accommodating to various types of generators without alteration.

Still another object or this invention is to provide an improved form of voltageregulator of the vibratory type which is applicable, without alteration, to various difierent makes of generators within a given class and which is of very compact and economical construction and capable of operating very eificiently for effectively maintaining the terminal voltage of the generator with- 5 inrelatively close limits and to accomplish this function with a minimum amount of sparking at the contacts.

Other objects and advantages of this invention will be apparent from the following description, 10 when taken in conjunction with the accompanying sheet of drawing, wherein Fig. l is a diagram illustrating a generating system which embodies my novel regulating means. I

Fig. 2 is a diagram illustrating another generating system embodying my novel regulating means.

Fig. 3 15 a diagram illustrating the, same system as in Fig. 1 but with the generator shown as a 20 conventional two-brush shunt machine.

Detailed reference will now be made to the accompanying drawing wherein I have illustrated improved regulating means for use with variable speed generators and which, as mentioned above, 25 may be embodied in a generating system intended for vehicle lighting and battery charging purposes, or which may be embodied in various other generating systems.

Referring first to the arrangement illustrated in Fig. l of the drawing, it will beseen that I have shown a generator Ill to which my voltage regulating device II has been applied. The generator illustrated in this instance is a generator of the three-brush type having an armature l2 and a field winding l3, although the invention hereinafter to be described is also readily applicable to generators of the conventional two-brush type. The generator I0 is here shown as having main brushes l4 and I5, and anauxiliary or third brush it to which one end of the field I3 is connected by the conductor I1. Load conductors l8 and I9 may be connected, respectively, to the main brushes l4 and I! for supplying generated power for the operation of lamps 20, for the charging of the storage battery 2|, or for various other purposes. Suitable switch means such as a conventional reverse current cut-out or the prior art, or a simple form of switch 22 may be provided for controlling the external load circuit.

The regulator itself comprises an electromagnet 23, and a vibratory armature 24 which is actuated in response to changes in the energization or the electromagnet. The electromagnet 23 is closed. This spring 2 provided with a suitable magnetizable frame 28 on which the windings or coils 2B and 21 are arranged. The, armature may be suitably mounted on the frame 25 as by means of the flexible, electrically conducting, connection it.

The regulator ii is also provided with pairs of cooperating contacts which are rendered efiective by vibration of the armature ior controlling the excitation of the field it, in a manner to be presently explained. These contacts are here shown as comprising stationary contacts 29 and 3d, and movable contacts ti and 32 which are carried by the armature 2G for cooperation with the station= my contacts. A suitable spring, such as the tension spring 33, may be connected to the armature it for normally biasing the same in a direction to cause the contacts 253 and St to be is of such character, however, that'when the electromagnet 23 is suficient- 1y energized, the armature 2% will be moved in opposition to the spring 83 to separate the contacts 29 and 3! and, in some instances, to close the contacts 30 and 32'.

.For varying the field excitation, I provide, a field regulating resistance 35 which is adapted to be intermittently connected into and short-circuited from the circuit of the field i3 by the opening and closing oi the

contacts

29 and 36. This resistance is also adapted to be connected, alternately, into the circuit of the field i3 and an auxiliary load circuit across the main brushes of the generator, by the opening and closing oi? the

contacts

36 and 32. Although field regulating resistances have been used heretofore as a part of voltage regulating devices, the present invention contemplates the employment of a special form oi field regulating resistance which, as mentioned above, has a variable resistance value and the effective value of the resistance is dependent upon the terminal voltage of the generator. As will be seen from the circuit arrangements presently to be traced, the effective value of the field regulating resistance 35 is such as to automatically adapt the regulator, without alteration, to various makes of generators within a given class, and 1 thereby makes the regulating device one of more or less universal application.

In the accomplishment of the end sought, namely that of rendering the regulator universally applicable to various makes of generators, I employ as the resistance having a relatively high temperature coeficient. Although various substances or various elements having this characteristic may be employed as this resistance, I find that good results can be obtained by the use of a tungsten filament lamp as this resistance. Good results can also be obtained when the resistance 35 is constructed as an iron wire resistance device.

Reverting temporarily to the construction oi the regulator l LI wish to point out that the electromagnet 23 may be variously constructed, but in this instance I have shown the electrcmagnet as embodying the coils 2t and 2! which correspond respectively with the coils 2i and '22 or my above cited prior patent. The coil 26 is a voltage coil which at all times responds to the terminal voltage of the generator, and the coil 2? is a secondary or auxiliary coil. These coils are arranged on the core or frame 25 in additive re lation and their combined effect is to produce an extremely rapid vibration of the armature 2 3 to cause correspondingly rapid opening and closing of the cooperating contacts.

When the generator is first set in operation, the

storage battery M 35 an element or device contacts 29 and 3i are closed, by reason of the actionof the spring 33, and the armature 23 is then connected directly to the main brush it by the conductor 36 so that a full flow of field current travels through the conductor 36 and the armature 2A to the field l3, and then through the conductor H back to the third brush it. At the same time, the voltage coil 26 responds to the terminal voltage of the generator by reason of this coil being connected across the main brushes it and i5. As seen in the drawing, one end of this coil is connected to the brush Id through the conductors 31 and 38, and the other end of this coil is connected to the brush l5 through the

conductors

39 and 36. While the contacts tfi'and 3i remain closed the coil 27 is also energized directly from the main brushes of the generator by reason of the fact that one end of this coil is connected to the armature 2 3 by the conductor it and the other end of this coil is connected to the conductor Ell.

When the speed of the generator has increased to the point where the magnetization of the frame 25, by the

coils

26 and 21, attracts the armature 24S and overcomes the spring 33, the contacts it and iii are opened. The opening of these contacts does not alter the circuit for the coil 26, but does alter the circuit for the coil 21 the field I3. By the opening of the contacts 2% and 3! the resistance 35 is connected in series with the field i3 and is also connected in series with the coil 27. The field excitation is thereby decreased and, as a result of the field magnetiza tion being decreased, the terminal voltage of the generator is lowered. The lowering of the terminal voltage of the generator, and the increase in the resistance of the circuit of the coil 2? by reason of the resistance 36 being connected thereinto, decreases the magnetization of the frame 25 of the regulator to permit the contacts 29 and St to be closed by the spring 33. The resistance 3% is thereupon short-circuited out of the field circult and out of the circuit of the coil 2i, and the terminal voltage of the generator and the magnetization of the frame 25 again increase.

Should the operating condition of the generator become abnormal, such as when the generator is driven at a relatively high speed or when the approaches a condition of full charge, the regulator it then operates to exercise a greater regulating action on the generator.

During such abnormal condition the terminal voltage of the generator is relatively high and the magnetization produced by the windings 26 and 2! is sufiicient to cause the armature 26 to opcrate intermittently on the'contacts 25 and 3B or to operate altogether on the contact 30.

When the terminal voltage of the generator has increased sumciently to cause the contact 232 to engage the contact 30, the resistance 35 is connected into an auxiliary load circuit across the main brushes of the generator. This auxiliary load circuit may be traced from the brush it through the resistance 35 to the armature 2d, and then through contacts 32 and 3B and through conductor 38 to main brush It.

It will be observed from the novel circuit arrangement illustrated, that when contacts 38 and 32 are closed the conductor load circuit just traced substantially short circuits the field winding i3 and also the magnet coil 21. Since the windings i3 and 21 are of a relatively high resistance as compared to the conductor 38, it will be seen that when the contacts 3t and 82 are closed most of the current will flow The collapse of the main field of the generator causes a desired sudden drop in the terminal voltage of the machine, and the collapse of the magnetic field of the winding 21 causes a sudden decrease in the magnetization of the regulator. The drop in the terminal voltage of the generator, due to the collapse of the field flux, also causes the magnetization of the voltage coil 26 to be correspondingly reduced. This reduced magnetization of the regulator allows the spring 33 to open the

contacts

30 and 32 thereby opening the short circuit and reestablishing the field circuit through the resistor 35. Because of the sudden and substantially complete deenergization of the windings l3 and 21 which occurs upon the closing of

contacts

30 and 32, I find that the armature 24 is vibrated at a very high rate and that very effective voltage regulation is obtained with only a small amount of sparking at the contacts.

It will also be observed that in the case of the third brush machine illustrated in Fig. 1, the establishment of the auxiliary load circuit by the closing of the

contacts

30 and 32 causes the field winding to be connected betweenthe main brush l4 and the third brush I 5. Since the latter brush is positive with respect to brush l4 there will be a tendency for a reversal of current fiow through the field Winding which would further accelerate the deenergization of this winding and the collapse of the field fiux and thus increase the effectiveness'ofvthe regulation. Whether or not actual reversal of current. takes place in the field winding will depend upon the resistance values employed, speed and load conditions and possibly other factors. I

As stated above, the resistance 35 has a relatively high temperature coefiicient and the effect of this on the operation of the regulator is to increase the resistance value of this element when the terminal voltage of the generator increases. Thus, when the

contacts

29 and 30 are being rapidly opened and closed and the resistance 35 is 7 thereby being intermittently connected into and short-circuited from the field circuit, and the' terminal voltage of the generator tends to increase in spite of the regulation thereby produced, there will be an increased fiow of current through the resistance element 35v and, because of its high temperature coefiicient, its resistance value will be correspondingly increased. Such increase in the resistance value of this element amounts to inserting additional resistance into the field cir cuit and into the circuit of the coil 21 which affords additional regulation of the generator.

When the

contacts

30 and 32 are being opened and closed, as upon the occurrence of an operating condition which requires additional voltage regulation, an auxiliary'circuit is intermittently established across the main brushes, as explained above, with a portion of such circuit substantially short-circuiting the regulator winding 21 and the field winding l3. Whenever the

contacts

39 and 32 close, the resistance 35 is included in the auxiliary generator circuit just mentioned and whenever they open, this resistance is inserted in the field circuit. During such time as the regulator armature is operating on the contact 29 and conditions are such that the terminal voltage of the generator is increasing, the resistance contact 5 i.

35 will be in the field circuit for an increased pe-' riod of time andits resistance value will increase because of its positive temperature coefiicient.

If conditions are such that the terminal voltage continues to increase, the armature of the regulator will ultimately operate on the contact 30, but as seen from the foregoing explanation of operation, when the contact 32 first engages the contact 30 the resistance value of the element 35 will be relatively high. If the terminal voltage of the generator continues to increase after closing of

contacts

30 and 32 the resistance of the element 35 will increase further because of its positive temperature coefflcient. It is desirable that the element 35 have a relatively high resistance value when the

contacts

30 and 32 are closed, so as to prevent a heavy flow of current through the auxiliary circuit of the generator which would otherwise cause burning of the contacts. It will be noted however that when the resistance element 35 is placed in the auxiliary circuit by the closing of

contacts

30 and 32, its location in the circuit is such that it does not prevent another part of the auxiliary circuit from'substantially short circuiting the regulator coil 2'5 and the field winding l3 as explained above.

It will thus be seen that the regulating resistance. is self-adjusting as to its resistance value, and because of this feature the regulator can be applied to different makes of generators and the self-adjustment afforded by the resistance element will enable the regulator to adapt itself to eflicient cooperation with the generator to which it is applied.

In Fig. 2 of the drawing I have illustrated regulating means which is generally similar to that illustrated in Fig. 1, but wherein slightly different circuit connections are employed. In the arrangement ,of-- Fig. 2 the generator 49 is a three-brush generator similar to the generator I8; of Fig. l, and is provided with a field 4i. One end of the field windingis connected to the third brush 42 and the other end is connected to the coil 43 of the regulator

M. Load conductors

45 and 46 are connected to the main brushes 4'! and 48 for supplying generated current to the lamps 49, to the battery 59, or for other uses.

The regulator 44 is also provided with a voltage coil 5i which is connected across the main brushes 4! and 48, one end 01' the coil being connected to the brush 41 through the conductor 52, the stationary contact 53 and the conductor 55, while the other end of the coil is connected to the brush 48 through the conductors 55 and 56. The coils 43 and 5| of the regulator 44 correspond generally as to construction and function to the coils 2'! and 26 of the arrangement shown in Fig. l. A vibratory armature 58 is arranged to respond to magnetization produced by the coils 43 and 5i so that

contacts

59 and 60 carried by the armature will cooperate, respectively, with stationary contacts 53 and 6E.

Fig. 1, is arranged with the ends thereof connected respectivelyto the armature 58 and the During low speed operation of the generator the contacts 60 and 6! are intermittently opened and closed to thereby connect the resistance 62' mittently opened and closed to thereby intermittently establish an auxiliary load circuit across the main brushes of the generator and in which A resistance element 62, similar to the resistance element 35 of I through conductor circuit is included the resistance element 62. The circuit which energizes the field 41 while the contacts 60 and BI are open, may be traced from the main brush 48 through conductors 56 and 83, and then through resistance element $2, armature 58 and flexible connection til to the magnet frame 66. Since one end of the winding 43 is connected to the magnet frame 55 the circuit may be traced further through the winding 43 and through the field windingdl back to the third brush 42. Likewise, the auxiliary load circuit which is connected across the main brushes while the

contacts

58 and 59 are closed, may be traced from main brush 48 through conductors 55 and 63, and then through resistance element 52, armature 58, and through

contacts

59 and 53 and 54 back to the main brush M.

The resistance element 62 is similar to the resistance element of Fig. l in that this element has a high temperature coemcient and, during the operation of the regulator, the resistance or this element varies to provide the correct amount of resistance necessary for efiicient cooperation between the regulator and the particular generator to which the regulator has been applied. Thus, during the operation of the regulating meansof Fig. 2, an increase in the terminal voltage of the generator will tend to maintain the contacts Eli and Bi separated during a longer period of time but, during that period, current flows through the resistance 62 since it is then in series with the field circuit, and the greater the flow of current through the resistance element the greater will be the increase in the resistance value of this element. Similarly, when the speed of the generator is relatively high and there is a tendency to

maintainthe contacts

53 and 59 in closed relation during a longer period of time, the correspondingly higher voltage of the generator will cause an increased current fiow through the resistance element 62, which is then connected into the auxiliary load circuit across the main brushes, and will result in an increase in; the resistance of this element. In both cases the increase in the resistance of the element 82 enlarges the capacity or regulating ability of the regulator to such an extent that the terminal voltage of any type of generator to which the device is applied is maintained substantially constant for all operating conditions. i

In Fig. 3 of the drawing I have shown a 'system which is identical with that of Fig. l with the exception that the generator. i0 is a conventional shunt machinev instead of a third brush machine and has the field winding 13' thereof connected to the main brush l4. I'he function ing 01 the system of Fig. 3 is identical with that of the system of Fig. 1 except that there is no tendency for a reversal of current in the field winding, I

From the accompanying drawing and foregoing description it should now be readily understood, that I have provided an improved form 0! voltage regulator wherein the regulating resistance element is a resistance having a high temperature .coeflicient, and that this characteristic of the re'-' sistance element causes a variation inthe eflfctive value of the resistance as changes occur in the operating condition of the generator. This 'f the resistance value of the self-adjustment the regulator to automaticallyelement enables accommodate itself particular generator to which the regulator is applied and, by reason of this automatic seliadjustment, my improved voltage regulator is unihaving a coil responsive of the generator and to the characteristics of the aosaoee tend to be limited to the precise arrangements of parts and circuit connections illustrated and described. but regard my invention as including such changes and modifications as do not involve a departure from the the scope of the appended claims.

Having thus described my invention, I claim:

1. In combination, a generator having a shunt field winding, a regulator comprising a magnet to the terminal voltage a second coil in series with the field winding, a vibratory member adapted to be actuated by the magnet, a pair of contacts in the field circuit and adapted to be intermittently closed and opened-by vibration of said member, a resistance element having its respective ends electrically connected with the contacts of said pair whereby opening of the contacts connects the resistance element in series with the field and with said second coil and closing of the conacts short-circuits the resistance, a third contact with which one contact of said pair has vibratory cooperation, and circuit connections whereby engagement of said one contact and said third contact connects said resistance element in a circuit across the terminals of the generator with a portion of the latter circuit in parallel with the field winding.

2. In combination, a generator having a shunt tive ends electrically connected with the'contacts v of said pair whereby opening of the contacts connects the resistance element in series with the field spirit of the invention and and with said second coil and closing or the con-;

tacts short-circuits the resistance, a third contact with which one contact of said pair has 'vibratory cooperation, and circuit connections whereby engagement of said one contact and said third contact connectasaid resistance element in a circuit across the-terminals of the generator, said resistance element having a high positive temperature coefiicient whereby its resistance value increases with an increase in the terminal voltage of thegenerator.

3. In combination, a generator having a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a circuit for the field winding including a resistor, a pair of contacts adapted to be operated by the vibratory member for intermittently short circuiting said resistor out of the field circuit during one'condition oi-operation'oi the generator, said magnet coils including a voltage coil and acoil additive to the voltage coil, a second pair of contacts adapted to be operated by the vibratorymember during another operating condition of the generator, and circuit-connections controlled by the second pair. of contacts for substantially short circuiting} said field winding and said additive coil.

In combination, a generator having a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a circuit for the field winding including a resistor, a pair of contacts adapted to be operated by the vibratory member for intermittently short-eircuiting said resistor out of the field circuit during one condition of operation of the generator, said magnet coils including a voltage coil and a coil additive to the voltage coil, a second pair of contacts adapted to be operated by the vibratory member during 'another operating condition of the generator, and circuit connections controlled by the second pair of contacts for connecting said resistor intoan auxiliary load circuit across the generator with a part of said auxiliary load circuit substantially short circuiting said field winding and said additive coil.

5. In combination, a generator having a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a circuit for the field winding including a resistor, a pair of contacts adapted to be operated by the vibratory member for intermittently short-eircuiting said resistor out of the field circuit during one condition of operation'of the generator, said magnet coils including a voltage coil and a coil additive to the voltage coil, a second pair of contacts adapted to be operated by the vibratory member during another operating condition ofthe generator, and circuit connections controlled by the second pair of contacts for substantially short circuiting said field winding and said additive coil, said resistor having a relatively high positive temperature coeificient characteristic. I

6. In combination, a generator having afield winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a circuit for the field winding including a resistor, a pair of contacts adapted to be operated by the vibratory member for intermittently short-circuiting said resistor out of the field circuit during one condition of operation of the generator, said magnet coils including a voltage coil and a coil additive to the voltage coil, a second pair of contacts adapted to be operated by the vibratory member during another operating condition of the generator, and circuit connections controlled by the second pair of contacts for connecting said resistor into an auxiliary load circuit across the generator with a part of said auxiliary load circuit substantially short circuiting said field winding and said additive coil, said resistor having a relatively high positive temperature coeiiicient characteristic.

'7. In combination, a generator having a field winding, said generator also having a pair of main brushes and a third brush to which the inner end of the field winding is connected, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, said energizing coils including a voltage coil and a coil additive'to the voltage coil, means connecting the outer end oi said field winding with one of said main brushes including a resistor, a pair of contacts adapted to be operated by the vibratory member for intermittently short eircuiting said resistor out of the field circuit during one condition of operation of the generator, a second pair of contacts adapted to be operated by said vibratory member during another operating condition of the generator, and circuit connections controlled by the second pair of contacts for intermittently connecting said resistor into an auxiliary load circuit across the main brushes with a portion of such load circuit short circuiting said additive coil and connecting the outer end of the field winding with the other of said main brushes.

8. In combination, a generator having a field.

winding, said generator also having a pair of main brushes and a third brush to which the inner end of the field winding is connected, a

regulator comprising a magnet having energizing another operating condition of the generator,

and circuit connections controlled by the second pair of contacts for intermittently connecting said resistor into an auxiliary load circuit across the main brushes with a portion .of such load circuit short circuit-ing said additive coil and corn necting the outer end of the field winding with the other of said main brushes, said resistor having a relatively high positive temperature coefiicient characteristic.

9. In combination, a generator having a field winding, said generator also having a pair of main,brushes and a third brush to which the inner end of the field winding is connected, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, said energizing coils including a voltage coil and a coil additive to the voltage coil, a pair of contacts between which said vibratory member is operable, a spring biasing said vibratory member toward one contact of said pair, said one contact being connected with one of said main brushes, said field winding having the outer end thereof electrically connected with said vibratory member, a resistor electrically connected with said one main brush and with said vibratory member, one end of said voltage coil being electrically connected with said one 'brush and one end of said additive coil being electrically connected with said vibratory member, and means electrically connecting the other contact of said pair and the other ends of said' magnet coils with the other of said main brushes. 10. In combination, a generator having a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted 11. In combination, a generator having a field,

winding, a. regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a circuit for the field winding including a resistor, a pair of contacts adapted to be closed by the vibratory member for intermittently short-eircuiting said resistor out of the field circuit, said magnet coils including a voltage coil and an auxiliary coil, a

second pair of contacts adapted to be operated,

byv the vibratory member, and circuit connections controlled by the second pair of contacts for connecting said resistor into an auxiliary load circuit across the generator with a part of said auxiliary load circuit substantially short-circuiting. said field winding and said auxiliary coil.

12. In combination, a generator having a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a pair of contacts adapted to be opened and closed by operation oi the vibratory member, a circuit for the field winding including said pair of contacts, said magnet coils including a voltage coil and an auxiliary coil,

a second pair of contacts-adapted to be opened and closed by operationof said vibratory member, and circuit connections controlled by said second pair of contacts whereby closing of the latter causes the field winding to be substantially deenergized and one of said magnet coils to be short-circuited.

13. In combination, a generator having brushes and a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a pair of contacts adapted to be opened and closed by operation of the vibratory memberfla circuit .for the field winding including said pair of contacts, said magnet coils including a voltage coil and an auxiliary coil, a second pair of contacts adapted to be opened and closed by operation of said vibratory member, and circuit connections controlled by said second pair of contacts where- 5,

by-closing oi the latter establishesan external circuit across brushes of the generator with a portion of such external circuit substantially short-circuiting said field winding and said auxiliary coil. l0 14. In combination, a generator having a field winding, a regulator comprising a magnet having energizing coils and a vibratory member adapted to be actuated by the magnet, a circuit for the field winding including a resistor, a pair 15 of contacts adapted to beclosed by the vibratory member for intermittently short-circuiting said resistor out of the field circuit, said magnet coils including a voltage coil and an auxiliary coil, 8.

second pair of contacts adapted to be operated 20 by the. vibratory member, and circuit connections controlled by the second pair of contacts for connecting said resistor into an auxiliary circuit across the generator with a portion of such auxiliary circuit in shunt relation to the field wind- 25 ing circuit, said resistor having a relatively high positive temperature co-efflcient such that its resistance value is self-adjusting and is relatively high when connected into the auxiliary circuit by said second pair of contacts.

'BE'I'I MZLEECE.