US2356629A - Electrical regulator - Google Patents

Description

Aug. 22, 1944. J STRATTON 2,356,629

ELECTRICAL REGULATOR Filed May a, 1941 Inventor J63? ry ,L VStF tLOn $F4J MAIN Bus by Patented Aug. 22, 1944 ELECTRICAL REGULATOR Jerry L. Stratton, Schenectady,

General Electric Company,

New York N. Y., assignor to a. corporation of Application May 8, 1941, Serial No. 392,416

3 Claims.

This invention relates to electrical regulators and more particularly to improvements in automatic variable-resistance-type electrical regulators.

Automatic variable-resistance-type regulators are commonly used to maintain constant automatically an electrical condition such as the volt age of a dynamo electric machine. In some classes of service the speed of the dynamo electric machine is constant, whereas in other classes of service, such as vehicles whose speed is variable, the speed of the dynamo electric machine varies so that the duty imposed on the regulator is more severe in, that it has to counteract the additional effect of changes in speedas well as the common effect of changes in load on the voltage of the machine. The trend is toward the use of larger and larger amounts of electrical energy on vehicles, thus requiring larger and larger size gen." erators to supply the load and in certain classes of service, such as in airplanes, weight is an important factor, b that in such service the ,duty on the regulator is increasing'while it is desirable that the weight of the regulator be kept as low as possible. i

In accordance with this invention there is provided a novel and simple resistance-type regulator which is relatively low in weight in comparison with the amount of current which it can control. It is characterized by the use of a plurality of spring contact fingers connected respectively to taps in fixed resistors, the contact fingers all making contact with a common conducting element for short circuiting the resistor and being moved out of contact with the common conducting element successively so as to increase the effective value of the resistance. In this manner each contact finger normally handles only a small portion of the total resistor current and the various contact resistances are in parallel rather than in series.

An object of the invention is to provide a new and improved electrical regulator.

Another object of the invention is to provide a low-weight high-capacity automatic resistance regulator. i

This invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing Fig. l is a front elevation of an embodiment of the regulator, Fig. 2 is a side elevation of the regulator shown in Fig. 1 when viewed from the right-hand end thereof, and Fig.

3 is a circuit diagram of the regulator connections 55 arms in which the essential elements of the regulator are shown in exaggerated perspective.

Referring now to the drawing, in which like elements will be designated by similar reference character throughout the several views, the regulator is shown mounted on a suitable base I which is shown as substantially rectangular in shape and which may be made of any suitable material, such as aluminum. Mounted at the top of this support by means of studs 2 are four resistance sticks 3, 4, 5 and 6, these sticks being insulated from the studs and from each other by insulating spacers or washers 1. These resistance sticks are of conventional construction consisting of a coil of resistance wire embedded in suitable insulation, such as porcelain, They are each provided with a plurality of taps designated generally by the reference numeral 8.

Mounted beneath the resistance sticks is a bracket 9 which is fastened to the support by suitable screws lll extending through the support. This bracket 9 carries or supports the rest of the regulator consisting of a, contact assembly and an operating magnet. The contact assembly consists of two vertically spaced tiers of parallel contact fingers, each tier of parallel contact fingers being arranged in a horizontal plane. The upper set of contact fingers is shown at l I and the lower set is shown at l2. The left-hand ends of the contact fingers II, a viewed in Fig. l, are embedded or clamped in an insulating block [3 and the left-hand ends of the contact fingers I2 are held in an insulating block I 4. The right-hand or free ends of the contact fingers engage or make contact with a conducting member I5. Below the insulating member M is an electromagnet assem bly I 6 having a' bracket I! at its left-hand end.

The bracket I1 is fastened to the bracket 9 by means of screws i8 whichextend through the insulating members i 3 and M and which serve to clamp them tightly. The common contact l5 for the sprin contact fingers is supported by the right-hand end of the magnet assemlny through extensions IS on the member l5 and by means of screws 20.

The magnet I6 is provided with an armature 2! which is effectively pivotally mounted on a novel frictionless suzport. This support con sists of a metal extension or plate 22 which is clamped between the insulating members i3 and M. This has a flat upper surface with a straight line edge. The armature is carried by a frame 23 to which is attached a pair of spacer members 24 carrying at their upper ends projecting 25 which have fiat end surfaces and straight edges. The projections 25 are in overlapp' i/ relation to the edge of the surface 22 and fiat blade springs 28 are mounted between the upper surface of 22 and the lower surfaces of 25 and have their ends fastened to these respective In this manner the frame 23 and conthe armature ii is restrained from moiy direction except one of rotation about re pivot al ng the axis created by the "Ulltalt oi the members 22 and 25. csrson of the location of this effective pivot "espect to the magnet and the armature, R if s by reason of the pivot being above no longituti rally between its ends, illle a. when atti c the1eft-hancl the magnet will h ve a dc w'l'lWZllCi of motion as well as an inward com- A Gill or" motion, these components being those the tangent of the circular path of the armac as the fiux produced by the magnet varies inversely with the distance from the center of its it w ll be seen that the inward motion of the armature toward the pole face and therer 'c toward a magnetic field of greater density be offset by the downward component of iron of the armature which is toward a density magnetic field. These two effects be made to neutralize each other so that the magnetic pull on the armature is substantially independent of its position.

Fastened to the outer end of the frame 23 by means of arms 2? is a frame 28 of insulating material of the same general shape as the mem ber l5 except that its two uppermost surfaces, correspondinc respectively to the surfaces of the ith which the separate tiers of conmake contact, are inclined slightly to those surfaces. Furthermore, the ihcse tvco surfaces of the insulating i 'e slightly different from each other, the slope of the topmost surface shown by the line 29 in 2 being slightly reater he slope Of the lower surface 36. means of this construction the inward and are! motion of the armature 21 under the "e of th magnet r le of the magnet .6

the g 28 move upn rcby t e left-hand contact finger of tier will be moved upwardly and out er 'icni conductin frame i5. Inc continued uni-.ard movementthe frame will cause the leit-hand contact finger of r t'er to be moved out of contact with Next the second contact finger f the lower tier and then he sec nger from the left of the upper alternately between the tiers will be moved out of conla frame 55.

magnet 56 is counterbalanced I iose upper end is fastened to the frame 23 and whose lower ac usl'ecl. Undesirable vibration of the armature ssembly is damped out by means of a dashpot ice f =eteci in parallel with one windings 3'? and 3s and with a series winding 39 which may either be a compounding winding or commutating winding. Resistors 3 and 5 are connected in series with the shunt field winding 31 and resistors 4 and 6 are connected in series with the shunt field winding 38. The two lefthand contact fingers of the lower tier are connected to the first two taps of the resistance 6 and the next two contact fingers of the lower tier are connected to the first two taps of the resistor 4. In a like manner the first two left-hand contact fingers of the upper tier l I are connected to the first two taps of the resistor 5 and the next two contact fingers of the upper tier H are connected to the first two taps of the resistor 3. While only four contact fingers have been shown in each tier in Fig, 3. it will be understood that actua ly ther a great many more contact fingers. For example, in Fig. 2 each tier is shown as consisting of ten contact fingers but in practice it is Often desirable to employ more than this.

The main control coil or the regulator is shown as consisting of two serially connected windings 40 and 4| which are connected between the ungrounded terminal of the generator and ground so that they carry current proportional to the generator voltage. An auxiliary winding 42 is also provided on the magnet and this is connected to the ungrounded side of the series winding so as to have impressed upon it a voltage which is proportional to the current in the generator. The circuit of this winding is completed through a switch 13 for connection to an equalizer bus to which similar windings of other regulators are connected when it is desired to have the regulator control parallel-connected generators. Such a connection amounts to a differential voltage connection so that the machine carrying the higher current will have a higher series winding voltage and hence the current through the equalizer bus will be in such a direction as to cause the coil 42 on the high voltage generator to aid the main coils and cause the corresponding coil 42 on the low voltage generators to o po e their associated main coils so as to equalize the voltage and prevent circulating currents in parallel-connected machines.

The operation of the regulator system is such that the armature 21 is in g n of equilibrium or balance between the opposing forces of the magnetv l6 and the spring 3|. If the voltage increases the armature is attracted, thereby raising insulating frame 28 and successively lifting contact fingers for engagement with the conducting member l5 thereby removin short c rcuits from increments of the resistors and thereby increasing the field resistance of the gen crater whereby field current and consequently its voltage will decrease. Similarly. a decrease in generator voltage will cause the reverse action thereby short circuiting successive increments of the resistors and increasing the field strength.

The connections are such that substantially balanced or equal current is maintained in the two field windings and at the same time substantial balance or equal current is maintained in all of the four resistors although, of course. the resistor currents will be substantially one-half the field winding currents. As the maximum voltage tending to cause arcing at each contact finger is that produced by the voltage drop in a section of each resistor between adjacent taps and as the current in each resistor is but half the field current of its associated field winding and as this field current is only one-half the total field current required by the machine, it will be seen that relatively small and delicate contacts and contact fingers will safely control a relatively large size generator.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therefore, it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a dynamo-electric generator having a plurality of field windings, a plurality of multi-tapped resistors connected respectively in circuit relation with said field windings, electroresponsive circuit making and breaking regulating mechanism for progressively short circuiting the taps of said resistors, and means included in said mechanism for causing said short circuiting to occur alternately in a predetermined sequence with respect to said resistors such that after a given small fraction of the number or taps have been short circuited in one resistor the same small fraction of the number of taps are short circuited a. tap at a time in another resistor until the same number'of taps are short circuited in all the resistors before an additional tap is short circuited in said oneresistor.

2. In combination, a dynamo-electric generator having a field winding, a plurality of multl-tapped resistors connected in circuit with said field winding, electroresponsive circuit making and breaking regulating mechanism for progressively short circuiting the taps of said resistors, and means included in said mechanism for causing said shortcircuiting' to occur alternately in a predetermined sequence with respect to said resistors such that after a given number of taps have been short circuited in one resistor the same number of taps are short circuited a tap at a time in another resistor at a time until the same number of taps are short-circuited in all the resistors before an additional tap is short circuited in said one resistor.

3. In combination, a dynamo-electric generator having a field winding, a plurality of multi-tapped resistors connected in circuit with said field winding, a plurality of contacts, movable means for effecting sequential and cumulative interconnec tion of said contacts, said contacts being connected respectively to said taps in such a manner that said means makes connection to said re- 25 sistors through the respective contacts for their taps in a predetermined cyclic sequence.

JERRY L. S'I'RA'ITON.

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