US2033013A - Electrical regulator - Google Patents

Description

March 3, 1936. 1.. w. THOMPSON ELECTRICAL REGULATOR Filed May 2, 1934 77 07715 LOADS.

InvenL r: Louis W. Thompson.

His Attorneg- Patented Mar. 3, 1936 UNITED STATES ELECTRICAL REGULATOR Louis W. Thompson, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application May 2, 1934, Serial No. 723,541

13 Claims.

My invention relates to electrical regulators and more particularly to improvements in vibratory contact type electrical regulators and regulating systems.

Automatic vibratory contact regulators are known which maintain an electrical condition of electrical apparatus, such for example, as the voltage of dynamo-electric machines, constant over a predetermined range of variation of another electrical condition of said apparatus and which act automatically to limit the maximum value of the other condition.

In accordance with my invention, I provide a novel regulator which has a pair of contacts, one of which is controlled and vibrated' in response to one condition of the regulated apparatus, and the other of which is controlled and vibrated in accordance with the other condition. Although my invention may be applied in a wide variety of ways, the application thereof in which I am at present particularly interested is to the electric generator which is provided on automobiles for charging the storage battery and for supplying current to the lights and ignition circuit. As thus applied, I control one of the contacts of my regulator in accordance with the voltage of the generator and the other of the contacts in accordance with the current of the generator, and the arrangement acts during normal current conditions to vibrate the voltage controlled contact with respect to the current controlled contact, which latter remains stationary, so as to hold substantially constant voltage, and during abnormal, or excessive current,

producing conditions, to vibrate the current controlled contact with respect to the voltage controlled contact, which then remains stationary, in such a. manner as to limit relatively abruptly the maximum value of current.

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

Another object of my invention is to provide a new and improved vibratory contact type regulator in which two relatively vibratory contacts are vibrated respectively in accordance with different operating conditions of the regulated apparatus. l

A further object of my invention is to provide a new and improved electrical regulating system.

My 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. 1 is a perspective view of an automatic vibratory contact regulator constructed in accordance with my invention, and Fig. 2 is a diagrammatic view of my-regulator, and its associated circuits, when it is applied to regulating the voltage and limiting the current of a direct current dynamo-electric generator o the type used for charging storage batteries on automobiles.

Referring now to the drawing, it will be seen that my regulator comprises a base member I, on which is mounted, in any suitable manner, a magnetic core member 2 which is so shaped as to provide separate magnetic circuits for two magnet windings 3 and 4, which will be referred to, respectively, as the voltage, or voltage responsive, winding and the current, or current limit, winding. By means of a suitable bracket 5, a contact member, comprising a biasing means in the form of a fiat blade spring 8 carrying an armature l and a contact 8 is supported in such a manner that the flux produced by the voltage winding 3 in its magnetic circuit will traverse the armature 1 and attract it against the resilience or bias of the spring 8. A stop member 9 is also mounted on the bracket 5 for limiting the motion of the armature l and the contact 8 away from the core 2, but this stop is not absolutely essential, as with the form of springfi shown the outward movement of the contact 8 is inherently limited. That is to say, with a fiat blade spring like 6, the design can easily be such that with but very 30 slight outward or upward movement of the contact 8 the spring 8 will be in its normal, free or midposition and will be substantially wholly unstressed. Mounted on a suitable bracket I0 is another contact member which is shown as a pivotally mounted element ll carrying a contact l2 for cooperation with the contact 8 and being biased by any suitable means, such as by a flat blade spring lit in such a direction as to urge contact [2 toward contact 8. However, the motion of contact I! toward contact 8 is limited by a stop member l3, which is supported by the bracket l0 and which bears directly against-the element II. The element I I is so mounted that it acts as an armature for the magnet winding 4 5 and the arrangement is such that the pull of this magnet when it exceeds the counterforce of the biasing spring l3 causes the contact I! to move away from the contact 8. The biasing force of the spring i3 is stronger than the biasing force of the spring 8 so that the contact member H carrying the contact I! is normally against its stop l3.

From the above construction, it will be seen that whenever the pull or excitation of voltage magnet 3 exceeds a predetermined value, which value is determined by the strength of spring member 6, the contact 8 will leave the contact I2, and due to the fact that the contact member carrying the contact I2 is riormally against the stop I3, there will be no follow-up motion of contact I2, so that with respect to contact 3, contact I2 is, in effect, a stationary contact. Whenever, the pull of current limit magnet 4 exceeds the counter'forceof biasing spring I8 the contact I2 will move away from the contact 8, and due either to the stop 9 or to the inherent characteristic of the spring 6, there is but a very limited follow-up motion possible for the contact 3.

During the operation of my regulator, contact I2 is normally stationary and contact '8 vibrates, butwhen the current in the winding t exceeds a predetermined value the contact I2 vibrates and the contact 8 becomes stationary. Consequently, it is convenient to refer to contact 8 as the normally vibratory contact andto contact I2 as'the normally stationary contact.

As shown in Fig. 2, my regulator is applied in an automatic regulating system for a direct current generator I5 for charging a storage battery I6. For convenience, ground returns are shown for the circuits of Fig. 2. Thus, by, way of example, the negative terminal of the generator I5 is grounded and the positive terminal thereof is connected to the positive terminal of the battery I6 through the current winding 4%, a current winding I1 and a set of main contacts E8, of a reverse current relay or cutout I9. The negative terminal of the battery is, of course, grounded. The function of the reverse current relay I3, which is used on substantially all circuits of this character, is to prevent the battery from discharging through the generator when the latter is idle, or when its voltage is below the voltage of the battery. This relayis also provided with a shunt or voltage winding 20 connected between the positive terminal of the generator I5 and ground. The movable one of the contacts I8 of the cutout I 9 is connected to the voltage winding 3 of the regulator and a set of back contacts 2i, on the reverse current relay, are arranged to short circuit the winding 3 when the cutout is open, that is to say, when the relay I9 is deactuated. The stationary one of the contacts 2i is connected to a resistor 22 which, when the contacts 2i are open, is in series with the voltage winding 3.

The principal function of the resistor 22 is to calibrate the voltage regulator, or voltage winding 3 so that at the particular normal value of voltage which it is desired to hold constant, the current in the winding ,3 will just be insufiicient to cause contact 8 to leave contact I2. Consequently, any higher voltage will cause contact 8 to leave contact I2.

The function of the back contacts 2i is to insure positive actuation of the relay I9. Thus, the contacts 2I serve to control the calibration of the voltage regulating elements of the regulator in that when they are closed the regulator holds a much higher voltage than when they are open, in fact, when the contacts 2i are closed the regulator does not operate as a voltage regulator at all due to the fact that voltage winding 3 is short circuited. Therefore, as the generator voltage builds up,.it can attain a. momentary value which ismuch higher than the normal value and this serves to give the shunt winding 20 of the relay is a strong energization so that the relay is very positively actuated thereby to close its main contacts I8. The fundamental reason why this is desirable is that in battery charging circuits, due to their relatively low resistance, the proper generator voltage should be very little greater than the counter-voltage of the battery, for proper charging current. Consequently, the regulator should normally hold a voltage which is very close to the normal battery voltage. However, the reverse current relay I9 should be designed to be actuated at a voltage which is substantially the same as the regulated voltage so as to make this relay sensitive enough to drop out on very small values of reverse current, which of course, is its primary function. It'thus follows that the normal voltage available for actuating the relay I9 is usually very little, if any, greater than the voltage at which the relay should drop out, and as a practical matter, it is diflicult to design a relay which will pull in and drop out at substantially the same values of energization.

The generator I5 is provided witha shunt field winding 23 in series with which is a regulating resistor 25. The resistor 24 is arranged to be short circuited by the contacts 8 and I 2, when they are in engagement, by means of a conductor 25 connected between the ungrounded end of the resistor 24 and the contact 8, the contact I2 being grounded as shown. In this manner vibratory engagement of contacts 8 and I2 controls a the effective value of resistor 26. In series with the contacts, that is to say, in the conductor 25,

' hunting winding, for whenever the contacts 8 and I2 are engaged, the field current flows through the winding 26 and this winding adding its pull to the voltage winding 3, serves to snap the contact 8 away from the contact I2, thereby speeding up the regulator action and minimizing hunting.

The operation of the system shown in Fig. 2 is as follows: As shown therein, the various parts are in the positions they assume when the entire system is deenergized so that in commencing the description of the operation let it be assumed that generator I5 has just been started and is being brought up to speed by any suitable driving means therefor, such as an automobile engine. As the generator I5 comes up to speed its voltage increases in proportion with the increase in speed, and due to the fact that contacts 8 and I2 are short circuiting the regulating resistor 2d, maximum field current, for any voltage, can flow in the winding 23. When the generator voltage exceeds the value at which winding 20 is designed to actuate relay I9 this relay closes its contacts I8 thereby completing the circuit between the generator and the battery through the windings 3 and ill. Winding I? is cumulatively wound with respect to winding 20 so that normal charging current increases the pull of the relay magnet causing the contacts I8 to remain in engagement. Actuation of the relay i9 opens the contacts 2i thereof thereby causing the voltage winding 3 to be energized through the calibrating resistor 22. If now the voltage of the charging circuit is above the normal value which it is desired to hold constant, the pull of the winding 3 causes the contact 8 to leave the contact I2 thereby inserting the resistor 25 in series with the winding 23, whereby the current in the field winding 23 is reduced, thereby reducing the voltage of generator I5. However, the opening of the contacts 8-I2 breaks the circuit for the anti-hunting winding 26 whereby the combined pull of windings 3 and 26 is decreased so that the contacts 8-I 2 snap closed again, but as soon as they close the pull of winding 26 increases so that if the combined pull of windings 3 and 26 exceeds a predetermined value which is determined by the calibrating resistor 22, the contacts 8 and I2 again separate. This results in a rapid vibratory action of the contact 8 with respect to the contact I2 with the result that an average current is held in winding 23 corresponding to the normal value of voltage which it is desired to hold constant.

With the principal exception of the voltage regulator calibration control by the cut-out I9, the above described operation is substantially that of a conventional vibratory contact regulator. However, the novel current limit feature of my invention will now be described.

If the current through the generator I5, and therefore through the current limit winding 4, exceeds a maximum allowable value, such for example as full load or rated current for the generator I 5, the pull of magnet 4 exceeds the counter pull of bias spring I4 whereby contact I2 is moved away from contact 8 thereby inserting the resistor 24 in series with the field winding 23 and reducing the generator voltage. This reduction in generator voltage, of course, reduces the current, so that contact I2 again engages contact 8,

but as soon as the current again tries to exceed the predetermined maximum allowable value the contact I2 will again be pulled away from the contact 8. Consequently, whenever load condi-- tions on the generator are such as to tend to cause it to be overloaded the current limit elements come into play and cause a vibratory action of the contact I2 with respect to the contact 8, which will then remain substantially stationary due to the fact that the voltage will then be below the normal voltage.

It will thus be seen that my regulator operates to regulate the voltage and to hold it constant over a predetermined current range and that when the current tends to exceed a predetermined allowable value my regulator acts as a current regulator to limit the current to a constant value over a predetermined voltage range from a maximum corresponding to the constant or normal value to a minimum value determined by the value of resistor 24 when it is permanently in series with the field winding 23, that is to say, when the contacts 8 and I2 are continuously separated. It will also be seen that normally vibratory contact 8 is controlled solely in accordance with voltage and the normally stationary contact I 2 is controlled solely in accordance with current and is vibrated during excess current conditions.

The current limit operation of my regulator is not necessarily always exactly as described above although that operation, in which the cur.- rent contact vibrates during overload conditions, gives a desirably sharp current limit in that the current cannot appreciably exceed the value at which the current limit feature first acts. The type of current limit operation depends upon the relative rates of change of pull of current magnet 4, and force of spring I4, on the armature II as -it changes its position. With a weak spring the magnet pull increases faster than the counterforce of the spring as the armature moves toward the magnet core. This results in the above described vibratory action of the current limit contact I2 for as soon as the current increases to the current limit point at which the magnet pull exceeds the counter-force of the spring an unstable condition exists because as the armature starts to move the force tending to move it increases at a greater rate than the spring force opposing the motion. With a stiff spring the counter-force of the spring increases at a greater rate than the pull of the magnet as the armature moves toward the core. Theoretically this should result in a stable non-vibratory motion of the current limit contact and with a sufficiently stiiT spring and sufilcient frictional damping that would be the case. The current contact I2 would move outward during any particular overload condition thus reducing the voltage held, which in turn would reduce the current, until stability was attained at a current slightly higher than that at which the current limit started to operate. The voltage regulator would then hold the lower voltage until the overload was removed. In certain other cases of springs just on the stiif side and with slight damping the current limit contact will vibrate due to mechanical shocks and jars and vibration of the whole mechanism.

It is emphasized, however, that the stiffness or weakness of the spring is purely relative to the rate of change of magnet pull with changes in armature position. This magnet pull build-up depends upon the constants and characteristics of the regulated circuit. For example, with a resistance load on the regulated generator the rate of change of load current with generator voltage is much less than with a battery load, which has a fairly constant counter voltage. Consequently, as the current limit armature starts to move the rate of change of pull on it will vary with the way the current changes as a result of this motion. The result is that any one regulator may have a weak spring or a stiff spring depending upon the kind of circuit regulated.

The current limit operation, as well as the voltage regulator operation, is also affected by the relative stiffness of voltage contact spring 6. With a relatively stiff spring the current limit contact I2 should be moved outwardly to secure the current limit action while with a relatively weak spring 6 the current limit contact I2 should be moved inwardly to secure the current limit action. This is because with a stiff spring 6 the voltage contact will separate from the current limit contact I2 at lower voltages as the contact I2 moves outward because then the counter force of the spring decreases faster than does the pull of the voltage magnet. With a weak spring the action is reversed and the pull of the magnet increases faster than does the counter pull of the spring as the contacts move inward.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made in my invention, and I aim, therefore, in the appended claims. to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. In combination, electrical apparatus, means for holding an electrical condition of said apparatus constant over a given range of variation of another electrical condition of said apparatus and for limiting the maximum value of said other condition, said means including a pair of contacts, means responsive to the first mentioned condition for vibrating one of said contacts into and out of engagement with the other contact which is substantially stationary over said given range of variation of the other condition, and means responsive to said maximum value of the other condition for vibrating said other contact into and out of engagement with the first contact which then remains substantially stationary.

2. In combination, an electric generator, a regulating resistance therefor, a pair of vibratory contacts connected to control the efiective' value of said resistance, means including a generator voltage responsive winding for normally controlling the vibratory engagement of said contacts, and means including a generator current responsive winding for assuming sole control of the vibratory engagement of said contacts when the generator current exceeds a predetermined value.

3. In combination, a dynamo-electric machine having a field winding, an automatic vibratory contact regulator for controlling the current in said winding, said regulator having a pair of cooperating relatively vibratory contacts, a generator voltage responsive magnet winding for vibrating one contact with respect to the other, and a generator over current responsive winding for vibrating said other contact with respect to the first which remains stationary during generator overcurrent conditions.

4. In combination, a pair of movable contacts, unequal biasing means urging each contact to ward the other, a stop for the contact with the stronger bias, and a separate electromagnet associated with each contact for moving its associated contact away from the other contact.

5. A regulator comprising, in combination, a normally stationary movably mounted contact member, a stop, relatively strong biasing means for movably holding said element against said stop, a normally vibratory contact member relatively weakly biased against said normally stationary contact member in a direction to oppose the biasing means of the latter, means for stopping the follow-up motion of said normally vibratory contact member with respect to said normally stationary contact member if the latter is moved away from its stop, a voltage magnet for controlling the motion of said normally vibratory contact member, and a current limit magnet for vibrating said normally stationary contact member into and out of engagement with said normally vibratory contact member.

6. In combination, an electric generator, 8. field winding therefor, a pair, of contacts connected to control the energization of said field winding, one of said contacts being biased into normal engagement with a stop, the other of said contacts being biased toward the 'first contact, a winding connected to be responsive to the voltage of said generator for moving said last mentioned contact away from the first mentioned contact when the voltage of said generator exceeds a predetermined value, and a winding connected to be responsive to the current of said generator for moving the first mentioned contact away from its stop when the current in said generator exceeds a predetermined safe maximum value.

7. In combination, a dynamo-electric generator I having a field winding, a pair of engageable movable contact members for controlling the current insaid field winding, a separate stop associated with each contact member for limiting its motion toward the other one, unequal biasing means for in said circuit.

urging each contact member in the direction of the other one whereby the contact member with the stronger bias will be against its stop, a magnet connected to be responsive to the voltage of said generator for vibrating the contact member having the weaker bias out of and into engagement with the other contact member so as to hold constant generator voltage, and a current limit magnet connected so as to respond to the current in said generator for vibrating the contactmember with the. stronger bias out of and into engagement with the other contact member at a predetermined maximum allowable generator current.

8. In combination, a direct current generator, a regulator therefor having a voltage responsive winding, and a reverse current relay connected in circuit with said generator and having a set of back contacts for short circuiting said voltage responsive winding.

9. In combination, a direct current generator, a storage battery to be charged thereby, a reverse-current cutout having a pair of contacts for connecting said generator to said battery when the generator voltage exceeds the battery voltage, a voltage regulator for said generator having a generator voltage responsive coil connected across said generator but not through said cutout contacts, and means controlled by said cutout for modifying the connections of said winding so as to cause said generator to produce a higher voltage when the contacts are open than when they are closed.

10. A vibratory contact voltage regulator having a normally vibratory voltage controlled conact for engaging a normally stationary contact, and a current limit for said regulator comprising current controlled means which has substantially.

no efl'ect on the position of said normally stationary contact over a normal current range but which moves said normally stationary contact relatively to the normally vibratory contact in response to current values in excess of said normal range.

11. In combination, an electric translating circuit whose voltage is to be regulated to a substantially constant value and whose current is to be limited to a safe maximum value, a regulator for said circuit comprising a normally stationary contact and a normally vibratory contact for engaging said normally stationary contact, means controlled by the intermittent engagement of said contacts for controlling the voltage of said circuit, a magnet responsive to the voltage of said circuit for controlling the motion of said normally vibratory contact, and a magnet responsive to the current in said circuit for acting upon said normally stationary contact in such a manner that over a predetermined normal range of current the position of said normally stationary contact does not appreciably change while for currents in excess of said normal range said normally stationary contact is moved relatively to said normally vibratory contact in such a direction as to reduce the current 12. A current limited vibratory contact voltage regulator comprising a pair of individually movable cooperating contacts, a voltage magnet for moving one of said contacts away from the other, a current magnet for moving the other contact away from the first, a relatively stifi spring for urging the voltage controlled contact toward the current controlled contact, a stronger spring for urging the current controlled contact toward the voltage controlled contact, and a stop for limiting the motion of the current controlled contact toward the voltage controlled contact.

13. A vibratory contact current limited voltage regulator comprising, in combination a pair of individually movable engaging current and voltage controlled contacts individually biased toward each other, a stop for limiting the motion of the current controlled contact toward the volt- 10 age controlled contact, a current magnet which has no efiect on the current contact unless it is energized by a current in excess of a predetermined normal current range for moving the current contact away from said stop if said range is exceeded and a voltage magnet for moving the voltage controlled contact away from the current controlled contact if said voltage magnet is energized by a voltage above a predetermined value.

LOUIS W. THOMPSON.

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