US2147456A - Regulating system - Google Patents

Description

Feb. 14, 1939.

H. C. NYCUM REGULATING SYSTEM Filed Feb. 28, 1935 WITNESSES: V.

62 /Z A' l1 /4 [NVENTOR Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE REGULATING SYSTEM Pennsylvania Application February 28, 1935, Serial No. 8,634

2 Claims.

matically comes into action if the basic or main control apparatus ceases to function.

Another object is to simplify the apparatus and circuits required to maintain forced vibration of the voltage-responsive control element.

A further object is to provide an improved method for compensating the regulator in accordance with changes in the loading of the regulated machine or circuit.

My invention itself, together with additional objects and advantages thereof, will best be understood from a description of a specific embodiment when taken in conjunction with the accompanying drawing in which the single figure is a diagrammatic view of apparatus and circuits illustrating the several improvements of my invention incorporated in a generator voltage regulating system.

Referring to the drawing, the regulating system there illustrated is adapted to maintain constant the voltage of an alternating-current generator in, the armature windings of which are directly connected to the conductors I! of a three-phase power circuit. The field windings of the generator derives energizing current from a directcurrent exciter IS, the field winding I8 of which is self-excited through a circuit which includes a pair of resistors or rheostats and 22.

Normally, resistor 22 is bridged by the contact member 24 of a contactor or relay 26, while resistor 20 is intermittently bridged by the contact member 28 of a second contactor or relay 3!) caused to rapidly open and close under the controlling action of a voltage sensitive element 32. This element is energized by, a measure of the voltage of circuit l2 through a pair of transformers 34 and 36 and a full wave rectifier 38.

I prefer to employ as the voltage-sensitive control element 32 a structure basically the same as that described in a patent to Walter Schaelchlin No. 1,820,712 granted August 25, 1931, and ascomprises a movable contact rnember 40, adapted to move between two stationary contact members R and L, which is carried by a bell crank lever 42 pivoted, at point 50, to a stationary or field member shown in the form of a tubular magnetizable portion 44 which is joined to one end of a core portion 46. The other end of this core extends, in the manner shown, back through the tubular portion 44'. The bell crank 42 carries an insulating tube 48 which is disposed within the tubular field portion 44 and around the corresponding portion of the core member 46 without touching either one. This bell crank is normally biased toward the right, tending to engage the contacts 40 and R by means of a spring 52.

In the field member 44-46 there is produced, by means of exciting coils 54 and 56, a flux which operates substantially uniformly across the gap between the tubular portion 44 and that part of the core 46 which lies therewithin. This magnetic field is effective in producing a uniform magnetic force which acts on the movable member with an intensity not varied by the position of the movable member.

The two exciting windings 54 and 56 are series connected with each other for energization by the output of the previously mentioned rectifier 38 which, in turn, is energized by a measure of the voltage of circuit l2. Winding 54 is wound on the insulating tube 48 attached to the bell crank 42 and lies within the aforementioned uniform magnetic field while winding 56 is wound on that portion of the core member 46 lying outside of the tubular frame portion 44 and thus produces the aforementioned field.

The electromagnetic reactions between the movable and stationary windings and this uniform air-gap field are such that magnetic pull produced on the bell crank 42 tends to open the contacts 40 and R and to close the contacts 40 and L against the pull of the biasing spring 52.

In the energizing circuit of the two exciting windings is connected a resistor 56 which, by virtue of a shunting connection established therearound by means of relay 30, serves to maintain the contacts 40 and R in a state of continuous vibration during normal operation of the regulat ing system.

During such normal operation when the voltage of circuit|2 is of the desired value the mag 'netic pull exerted by exciting windings 54 and 56 of the voltage sensitive element 32 is, when the resistor 58 is in the energizing circuit, insufiicient to overcome the tension of spring which accordingly biases movable contact member 4% into engagement with stationary member R. These contacts complete an actuating circuit for relay 36 which extends from the positive terminal of the exciter l6, through conductors 60, 6| and 62, the relay winding 64, conductor 65, contact members R and Bi) of device 32 and conductor 66 back to the negative terminal of exciter l6.

Thus energized relay 30 moves its contact member 28 upwardly thereby establishing a shunt connection around excitation adjusting resistor 20 by virtue of which connection the current supplied to the exciter field winding I8 is raised. As a result the exciter voltage and hence the energizing'current supplied to the field winding M of the regulated machine 10 starts to increase,

whichin turn causes the machine voltage to tend to rise.

In moving to the named actuated position, contact member 28 of relay 30 also completes a shunting circuit around the resistor 58, thereby increasing the current supplied to the windings 54 and 56 of device 32, which increase effects a separation of contact members 40 and R. This shunting circuit may be traced from the upper end of resistor 58 through conductor 61, relay contact member 26, conductor 6i, a protective fuse 12 and conductor 63 back to the lower end of resistor 58.

The named separation of contact members 40 and R deenergizes relay 30 allowing contact member 28 to move downwardly to the unactuated position shown. Such downward movement interrupts the shunt connection from around excitation-control resistor 20 and thereby reduces the current supplied to exciter field winding l8. By similarly interrupting the shunt connection from around resistor 58 the opening of contact member 28 also decreases the current supplied to the exciting windings of device 32. The resulting tendency for the voltage of regulated machine ID to decrease is thus accompanied by a re-engagement of contact members 40 and R and the cycle just described is caused to repeat itself at a frequency of several times per second.

Regulation of the voltage of machine I0 is, as in other vibratory regulating systems, thus effected by varying the time-closed to time-opened periods of the control device contacts 40 and R, the value of this ratio increasing when the machine voltage tends to fall below the desired value and decreasing when the opposite tendency is present.

One feature of my invention resides in the above-described scheme of shunting the vibration-forcing resistor 58 by thesame contact member 28 of relay 30 as functions in the main excitation control circuit. The simplicity of this arrangement constitutes a distinct advantage and is made possible by interposing the rectifier 38 between the alternating current regulated circuit l2 and the voltage sensitive control element 32. Such direct-current energization has the further advantage of allowing the magnetic field which acts in the device 32 to be unidirectional, thereby improving contact operation and reduc ing chattering tendencies.

Adjustment in the value of voltage which the regulating system will maintain may be effected by changing the setting of a voltage-adjusting rheostat 68 which may be placed at any convenient point in the energizing circuit of de-. vice 32.

Considering now the disclosed stand-by regulating arrangement of my invention, the need for this arises when, for any reason, excitation-controlling relay 30 fails to function in the manner desired as for example, to reopen'the contact member 28 thereof. In such case, the tendency is for the regulated voltage to rise, since resistor 20 is then continuously shunted from the excitation-supply circuit. To counteract this tendency, I provide the voltage-sensitive device 32 with a second stationary contact member L which when the voltage of circuit l2 hasrisen very slightly above the desired value is engaged by the movable member 40.

Such engagement completes an actuating circuit for the supplemental relay 26 which extends from the positive terminal of exciter I6 through conductors 60, 6| and 62, the relay winding 10, conductor II, the contacts L and 40 of device 32 and conductor 66 back to' the negative terminal of the exciter I6. Thus energized the relay 26 moves its contact member 24 upwardly thereby interrupting the normally maintained shunt circuit around resistor 22. The resulting insertion of this resistor in the excitation supply circuit reduces the voltage of exciter l6 and hence checks the voltage rise of the regulated machine I0.

As a result of the decreased excitation the machine voltage may tend to fall below the desired value in which case device 32 will separate contact member 40 from member L and thereby cause a re-establishment through contact member 24 of relay 26 of the shunt connection around resistor 22. This again causes the machinevoltage to start to rise and the cycle of operation just described continues to repeat itself rapidly.

It will thus be seen by means of this simple stand-by regulator equipment the voltage of the regulated machine is never permitted to appreciably rise above the desired value as it would were the stand-by equipment not to be provided. Inoperation the contact member 40 of device 32 merely moves across the small gap between the two stationary members R and L. Thus this previously unused but simple combination of ad ditional main contacts and a spare relay permits the use of a vibrating regulator with all its inherent advantages and with its chief disadvantage reduced to a minimum. As a further precaution, any conventional form ofalarm system may be combined to indicate when the stand-by equipment has been brought into continuous op-' eration.

A further feature of my invention resides in the novel method of compensating the regulator for changes in machine loading. To effect this compensation I provide upon the core 46 of the voltage sensitive device 32 an auxiliary winding 74 which, through a circuit which includes a potentiometer or voltage-dividing resistor 16, is energized by a measure of the voltage appearing across the exciter field winding 18. The disclosed parallel connection of thisresistor with the winding 74 tends to equalize the fluctuations in the voltage supplied to winding l8 and cause its average value to influence the compensating winding 14. Furthermore, the inductive characteristics of this winding serve to additionally smooth out the voltage fluctuations permitting in effect only the average to modify the action of.

the control element 32.

The nature of this modification is such that as the energizing voltage supplied to exciter winding l8 rises, as is the case when the output of the regulated machine i0 is increased, the device 32 will respond only to a higher value of machine voltage thereby producing the desired rising voltage-with-machine-load characteristic. By adjusting the position along resistor 16 of a tap connection 18, the degree of this rising characteristic may be modified to suit operating conditions. By reversing the connections of winding H a lowering-voltage-with-load characteristic may similarly be produced.

If desired, the described excitation-responsive compensating means may be supplemented by one which is directly responsive to the machine loading. Such is illustrated as comprising a resistor 80 connected in the energizing circuit of voltage sensitive element 32 and adapted to have circulated therethrough, by means of a current transformer 82, a current which is proportional to the output of the regulated machine l0. When the machine output increases the voltage drop across the resistor 80 similarly rises and produces the desired form of compensation. Reversal of connections changes it to a 'lowering-with-load variety.

While I have shown and described certain specific embodimentsof my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claims.

I claim as my invention:

1. In a regulator system, in combination, an electric generator, means for regulating an electric quantity responsive to the excitation of said generator comprising a field winding circuit including a pair of regulating resistors connected in series, a primary relay of the continuously vibrating type responsive to the regulatedquantity and having a movable contact member and a pair of fixed contact members, said relay be-' ing operative to cause intermittent engagement and separation of said movable contact member with one only of said fixed contact members to effect the intermittent shunting of one of said control resistors as the sole regulating resistor throughout the complete range of control of said field winding for controlling the regulated quantity within given limits and to cause intermittent engagement and separation of said movable contact member with the other of said fixed contact members to efiect the intermittent shunting of the other of said control resistors as the sole regulating resistor throughout the complete range of control of said field winding for controlling the regulated quantity within different limits.

2. In a regulator system, in combination, an electric generator, means for regulating an electric quantity that is responsive to the excitation of said generator comprising a field winding circuit including a pair of regulating resistors connected in series, a secondary relay adapted to close a circuit in shunt relation to one of said resistors and normally biased to a circuit interrupting position, a secondary relay adapted to close a circuit in shunt relation to the other of said resistors and normally biased to a circuit closing position, a primary relay of the continuously vibrating type responsive to the regulated quantity for controlling the operation of said secondary relays, said primary relay being operative to effect the intermittent closing and opening of said first-named secondary relay as the sole regulating element to vary the effective value of its associated resistor throughout the complete range of control of the field winding when the second named secondary relay is in a circuit closing position, said primary relay being operative to effect the intermittent closing and opening of said second-named secondary relay as the sole control element throughout the complete range of control of the field-winding when the first named secondary relay is in a circuit closing position.

HOMER C. NYCUM.

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