US2957138A

US2957138A - Voltage regulator adjustor

Info

Publication number: US2957138A
Application number: US745228A
Authority: US
Inventors: Anthony J Greco; James E Luckman; Malcolm I Dickinson
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-06-27
Filing date: 1958-06-27
Publication date: 1960-10-18
Anticipated expiration: 1977-10-18

Description

Oct. 18, 1960 A. J. GRECO ETAL VOLTAGE REGULATOR ADJUSTOR Filed June 27, 1958 120 V. A.C.

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' INVENTORS 23 24 ANTHONY .1. GREco 'y' pdl JAMES E. LucKMAN l" BY MALCOLM 1. mcKmsoN 21 cf W 2a v. uc'.L

, A TTORNE YS Oct. 18, 1960 A. J. GRECO ETAL 2,957,138

VOLTAGE: REGULATOR ADJUsToR ANTHONY J. GnEco JAMES s, LucKMAN BY MALCOLM I. nlcKlNsoN ATTORNEYS Patented Oct. 1S, 1960 VOLTAGE REGULATOR ADJUSTR Anthony J. Greco and James E. Luckman, Philadelphia, and Malcolm I. Dickinson, Levittown, Pa., assignors to the United States of America as represented by the Secretary of the Navy Filed June 27, 1958, Ser. No. 745,228

11 Claims. (Cl. 324-158) (Granted under Title 3'5, U.S. Code (1952), sec. 266) The invention disclosed herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

'Ihe present invention relates to a voltage regulator adjustor and more particularly to a voltage regulator adjustor in which the dynamic operating characteristics of a generator are closely simulated to facilitate the bench adjustment or test of a generator voltage regulator.

The voltage regulator of the type herein contemplated for adjustment or test utilizes a regulating resistance such as a carbon pile or the like, and an actuating potential coil which is operable in response to changes in line voltage to elect proportionate changes in resistance of the regulating resistance. The regulating resistance is usually connected in series with the shunt eld winding of a D C. generator or in the exciter circuit of an A.C. generator. A direct method of adjusting a voltage regulator of the type indicated is to manually make the necessary adjustments while the device `is dynamically operating in a generating system. Although such a technique is feasible, danger exists in that uncontrolled line voltage may result, or that voltage excursions detrimental to equipment may be precipitated. A generating system including a dummy `dissipative load may be utilized, but

such arrangement is tantamount to duplicating the actual e system, being characterized by unnecessary bulk and waste of electrical power. A known synthetic device for eecting adjustment of a carbon pile voltage regulator utilizes a flux-shifting transformer, the voltage output of which is rectilied and supplied to a potential coil, which causes the carbon pile to alter its resistance. A proportionate current corresponding to the `change in resistance is then supplied to a Winding of the transformer, causing the ilux to be shifted in a manner to approximate the transient voltage output characteristics of a generator under load. 'Ihis type of synthetic device does not subject the voltage regulator to `a realistic test since it lacks the dynamic capability for fully simulating changes in generator speed as Well as the transient line voltage characteristics peculiar to the system, occurring upon application or removal of load. Thus, While the methods and devices of the prior art for performing adjustment or test of a voltage regulator may be used, each possesses inherent limitations which preclude its general -acceptance in the art.

Apropos of the limitations of the methods and devices of the prior art, the novel voltage regulator adjustor of the instant invention eifeets simulation of a wide variety of transient voltage characteristics, as well as simulation in variation of generator speed. In this manner, a dynamic operating environment comparable with that in the actual generating system is provided such that not only is a voltage regulator subjected to a fully realistic test, but also, bench adjustment of the voltage regualtor is greatly facilitated without attendant deleterious elects upon the system. In essence, the inventive voltage regulator adjustor comprises a variable impedance reactor which is series electrically interposed between an A.C. source and the input circuit of a rectifier. The output circuit of the rectier supplies a potential coil, which actuates in conventional manner the regulating resistance ofthe regulator. A multi-tapped control winding of the variable impedance reactor is in series with the regulating resistance and operably effects a change in circuit impedance, controlling the input A.C. voltage to the rectifier. A positive amount of controlled instability is introduced into the circuit of the voltage regulator adjustor by means of a feedback winding wound on the core of the variable impedance reactor, the transient line voltage characteristics being imparted to the inventive device in this manner. Selective energization of the multi-tapped control winding provides for the simulation of different degrees of shock electrical loading, while manipulation of the output excitation voltage of an auto-transformer approximates changes in generator speed. Thus, in the manner summarily set forth the voltage regulator adjustor of the instant invention provides for dynamic operating conditions comparable with those in a generating system, greatly facilitating the test and adjustment of a voltage regulator of the type herein denoted.

An object of the present invention is the provision of the voltage regulator adjustor which simulates the voltage output characteristics of the generator under load for subjecting a voltage regulator to a fully realistic test.

Another object is to provide a voltage regulator adjustor which simulates Voltage output characteristics of a generator representative of changes in load in order to ascertain response of a voltage regulator which is being tested.

A further object of the invention is the provision of a voltage regulator adjustor which simulates changes in generator speed in order to ascertain response of a voltage regulator which is being tested.

Still another object is to provide a voltage regulator adjustor which simulates the transient voltage characteristics manifested on the line of a power system upon the application or the removal of load in order to determine the response of a voltage regulator being tested.

An additional object of the present invention is the provision of the voltage regulator adjustor which will accommodate the bench adjustment and test of a wide variety of types of voltage regulators under dynamic operating conditions comparable -With that in an actual generating system.

The exact nature of lthis invention as well as other objects and advantages thereof will be readily apparent from consideration of the following speciication to the annexed drawing in which:

Fig. l is an electrical schematic diagram of a preferred embodiment of the invention.

Fig. 2 is an electrical schematic diagram of alternative structure for jointly supplying by means of a common winding both bias and feedback to the variable impedance reactor `of the embodiment shown in Fig. 1.

Fig. 3 is an electrical schematic diagram of a modiiied form of Voltage regulator adjustor.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Fig. l an autotransformer 11, or the like, connected to a suitable A.C. source of conventional power frequency, which may be 400 cycles per second used in the instant invention. The adjustable output of auto-transformer 11 is connected to supply excitation to rectiiier 29 through the series connected windings 13 and `14 of the schematically shown variable impedance reactor 12 of a conventional type.

Vthel middle core leg of the reactor. 'Three windingsare Wound upon the middle leg of the. Variable-impedance reactor in the embodiment of Fig. l: A bias winding effective to control the operating point of the variable impedance reactor 12 is connected.throughY switch 2S,

resistors

26 and 27, .to a DC. source,.which mayibe preferably 2S volts used in the instant invention. A controlled winding. 16 is provided with a number of taps so that a discrete number of ampere-turns Ymaybe selectively applied through the shock loading switch 18 to the. core. of the variable. impedance. reactor 12.. The clockwise rotation of switch 18 causes the applied ampereturns to' be.reduced,'since increasing portions of control winding 16 areeffectively short circuited. A D.C. potential is supplied to. control winding 16 through. fixed resistor. 21, variable resistor. 22, and a carbon pile 32, or the like, of regulator 34 under test.. The current flowing in this winding is varied in conformancewith the changes in resistance of the carbonpile. A thirdwinding 17 functionsto supply reactor 12 a controlled amount of positive ampere-.turns in order. to simulate line voltage transients; This positive feedback winding is also wound on the middle leg of the core. of. variable impedance reactor 12. and is effective to modify the. saturable magnetic ux characteristics thereof. The A.C. component of voltagedevelopedacross resistor 21 is coupled through capacitor 2.3il and appears across resistor 24, the latter supplying this A.C. component to. the feedback winding 17. Switch 25. is provided for'selective application of this feedback voltage. Capacitor. 23 and resistor 24 are variable in. order to provide for dierent time response characteristics.

Rectifier 29 is a conventional bridge type. The input voltage is rectified and filtered by the condenser input pisection. filter 31. The output ofthe filter is applied tothe .potential coil. 33 which actuates the carbon pile. `32, asdenoted by the dottedY line notation. In order to accommodate the adjustment. of regulators in which the potential. coilshave different current requirements, resistorsl 3.5; and 36. are provided in shunt across coil 33. Thus, Variable resistor 35 may he. termed. a load balance adjust.

Referring next to Fig. 2, yit should. be understood that the. alternative. structure therein illustrated for jointly supplying bias. and feedback is electrically connected to terminals. 37., 38,39 and.41 in lieu of the corresponding structure shown in Fig.. 1. In this instance the steady state` D..C. bias voltage and A.C. components of feedback voltage is applied in common to winding 17 Variable .resistor 24 exercises ameasure of common control over both these voltages, while the magnitude of. feedback voltage. appliedV to winding 17, and.. therefore the effective NI operably coacting with the. variable impedance reactor 121, is an. inverse function of the capacitance of condenser 23. The arrangement depicted in Fig. 2 provides for the simulation of transient line voltageswhich have essentially dierent time response characteristics from that discussed in connection with Fig. l. Other illustrated circuit elements correspond with those. shown and discussed in connection with the preferred embodiment, of iFig.. l.

Fig. 3 illustrates an electrical schematic circuit of a modified form of voltage regulator adjustor. This specific embodiment does not embrace a controlled instability feature, but is capable of simulating line voltage variations due as a result of changes in either generator speed or load, includingr shock electrical loading. The variable impedance reactor 12 in this instance coacts with winding 16, which serves both-the bias and control function. Winding 16 is connected to a D C. voltage-supply through

resistors

21 and 23, and carbon pile 32 of regulator '34. The ampere-turns as seen by Winding 16 lvary in accordance with the manual adjustment of resistor 22 and the dynamic resistive changes of the carbon pile. As before, the load balance adjust resistor 35 accommodates voltage regulators in which potential coils thereof may have different current requirements.V Capacitor 42 having a value of 1000 microfarads or thereabouts, performs las a conventional filter element. While the simulation of changes in generator speed is similarly performed by means of auto-transformer 11 as in previous embodiments, line voltage variations resulting from changes in load is simulated in this instance by the selective application or removal of a resistive circuit connected across the output of the rectifier. This circuit may be comprised of an impedance consisting of an inductance and/or capacitance in additionV to resistance, thereby approximating the electrical character of the line load; but in the embodiment of Fig. 3, this circuit consists of resistor 43, switch 44` and variable resistor 45. The value of resistor 43 is chosen to simulate a full load condition when-variable resistor 45 is a minimum. Due to the internal voltage drop of both the. rectifier and the variable impedance reactor, the voltage presented the potential coil will vary with the selective application or removal ofthev resistive circuit. Thus, switch 44 functions as a shock electrical load switch.

The operation of the instant invention may be best set forth with respect to the preferred embodiment of Fig. 1. :In the steady state case in which a fixed A.C. voltage is applied to the circuit of the variable impedance reactor 12 and rectifier 29, the reactance drop across A.C. windings 13 and 14 assume a certain quiescent value, and the voltage applied to the input of rectifier 29 is the` vector difference of the auto-transformer output voltage and the reactive drop ofthe variable impedance reactor 12. The saturable flux characteristics of the reactor may be shifted to alter its output impedance by changing the operating point of the reactor as a function of the setting of bias control 26, which is adjusted to supply the desired amount of ampere-turns consistent with satisfactory operation of the voltage regulator adjustor.'V Assuming regulator 34 is to be adjusted, a rectified filtered voltage appears across the potential coil, and the load balance adjust resistor 35 is set to furnish the normal operating current for the coil. Resistor 22 may be set at any point in accordance with the degree of desired steady state loading. The setting of condenser 23 and resistor 24 is not critical, and may be established at a value which effects the desired transient voltage across potential coil '33 when the shock electrical load switch 18 is rotated.

Consider the dynamic operation involved when an increase in line Voltage yas a function of increased generator operating speed is simulated by manually increasing the voltage output of auto transformer 11. The impedance of windings 13 and 14 is reduced, resulting in a larger voltage being presented the rectifier. An increase in potential coil current results in the actuation ofthe carbon pile in a direction totincrease its resistance. The current of control winding 16 is reduced, causing the impedance of thel reactor to increase to thereby reduce the rectifier input voltage and the voltage across the potential coil. A fall in line voltage is instrumental in causing a similar set of events to occur. Hence, the denoted action simulates the behaviour of a generator in that a decrease in field current (carbon pile current) produces a decrease in loutput line voltage, and vice versa. Thus, in the instant invention an increase -in the applied A.C. input voltage simulatesk an increased 'operating speed of the generator and an attendant decrease in field current to give regulated output, while a decrease in applied A.C. voltage simulates a decrease of generator operating speed andan increase infield current necessary for a regulatedoutput.

The vstability of an adjusted regulator may be checked under shock loading by the switching arrangement provided in the preferred embodiment, whereby a selected number of turns can be added or shorted out. This action suddenly changes the eective NI of the control winding 16 and causes the regulator to seek a new 0perating point to restore regulated output. Thus, the abrupt application or removal of a load presented on a power line of a generating system is stimulated through the action of shock electrical load switch 18. In the embodiment of Fig. 3, shock electrical loading or unloading is simulated by actuating switch 44.

The character of the transient voltage `occurring during the shock loading may be made comparable with that appearing in an actual generating system. In this regard, the time response characteristics of the generatorregulator system is iniiuenced by the setting of condenser 23 and resistor 24, which are adjusted to impart the desired transient voltage across the potential coil when the shock load switch 18 is rotated. This specific objective is achieved by sensing for current variations in the carbon pile circuit. The current variations produce comparable voltage variations across resistor 21. The D.C. component of these variations is blocked by capacitor 22 in Fig. 1, and the effective ampere-turns as seen by the feedback winding 17 is derived across resistor 24. Hence, in this manner the character of the transient voltage occurring during shock loading may be varied over a considerable latitude.

Thus, in the manner described, the voltage regulator adjuster of the instant invention greatly facilitates the bench adjustment of a voltage regulator by providing dynamic operating conditions comparable in respects with those of an actual generating system. Not only may be simulated the transient line voltages of selectively variable time response characteristics, but in addition, different degrees of shock electrical loading are also provided so that a voltage regulator under adjustment may be subjected to a fully realistic test.

Obviously many modiiications and variations of the present invention are possible in the ylight of the above teachings. It is therefore to be understood that Within the scope of the appended claims, the invention may be practiced otherwise than Ias specifically described.

What is claimed is:

l. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a Varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformer means having an input circuit connected to an alternating current voltage source and an adjustable output circuit, variable impedance reactor means including a control Winding connected in series to a direct current voltage source through the variable resistance means and operable to control the output impedance of said reactor means, the input circuit of said rectiiier means being connected for excitation to the adjustable output circuit of the transformer means through said variableimpedance reactor means, the output circuit of the rectier means being connected in shunt with the varying potential responsive means of said voltage regulator, and selectively operable means connected in shunt with the output circuit of said rectiiier means for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

2. The apparatus of claim l in which the selectively operable means comprises a substantially resistive circuit including a switch for connecting said resistive circuit to the output circuit of the rectiiier means.

3. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means for controlling the variable resistance means, comprising: rectiiier means having an input circuit and an output circuit, trans'- former means having'an input circuit connected to an alternating `current voltage source and an adjustable output circuit, Variable impedance reactor means including a multi-tapped control winding connected in series to a direct current voltage source through the variable resistance means and operable to control the output impedance of said reactor means, the input circuit of said rectiier means being Yconnected for excitation to the adjustable output circuit of the transformer means through said variable impedance reactor means, the output circuits of the rectifier means being connected in shunt with the varying potential responsive means of said voltage regulator, and switch means connected to said multi-tapped control winding `and adapted to selectively short circuit predetermined portions thereof for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

4. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformer means having an input circuit connected to an alternating current source and an adjustable output circuit, variable impedance reactor means having a primary winding connected in series with a secondary Winding and including a control Winding connected in series to a -direct current voltage source through the variable resistance means, said control winding being operable to control the output impedance of the series connected primary and secondary windings, the input circuit of the rectiiier means being connected for excitation to the adjustable output circuit of the transformer means through the series connected primary and secondary windings of said reactor means, the output circuit of the rectifier means being connected in shunt with the varying potential responsive means of said regulator, adjustable resistive means connected in shunt with the output circuit of the rectifier means to adjust for normal operating current traversing the varying potential responsive means, and selectively operable means connected to said control winding and adapted to select portions thereof for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

5. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformer means having an input circuit connected to an alternating current voltage source and an adjustable output circuit, variable impedance reactor means having a primary Winding connected in series with a secondary winding and including a multi-tapped control winding connected in series to a direct current voltage source through the variable resistance means, said multi-tapped control winding being operable to control the output impedance of the series connected primary and secondary windings, the input circuit of the rectifier means being connected for excitation to the adjustable output circuit of the transformer means through the series connected primary and secondary windings of said reactor means, the output circuit of they reciier means being connected in shunt to the varying potential responsive means of said regulator, adjustable resistive means connected in shunt with the output circuit of the rectifier means to adjust yfor normal operating current traversing the varying potential responsive means, and switch means connected to said multi-tapped control winding and adapted to selectively short circuit predetermined por- 7 Y tions thereof for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the; dynamic operation of a generator under various conditions of load and speed issimulated to facilitate test of the voltage regulator.

6. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled tol a varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformer means having an input` circuit connected to an alternating current voltage', source and an adjustable output circuit, animpedance network means responsive to resistance changes in the variable resistance means to develop a feedback voltage of preselected time response characteristics, variable impedance reactor means having a plurality of windings including a primary winding connected in series with a secondary winding, a control Winding connected to a direct current source in series with said network means andl the variable resistance means, anda feedback-bias winding connected in series to the direct current'voltage source through said impedance network means to opeably modify the saturable ux operating characteristics of'the reactor means, the input circuit of the rectifier means being' connected for excitation to the Vadjustable output circuit of the transformer means through the series connected primary and secondary windings of said reactor means, the output circuit of said rectifier Vmeans being connectedv in'shunt to the varying potential responsive means .of said` regulator, and selectively operable means connected to said control winding andV adapted to select predetermined portions thereof for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

7. An apparatus for testing a voltage regulator of the type having variable resistancel means operably coupled to a varying potential responsive meansv for controllingy the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformerV means having an input circuit connected to an alternating current voltage source and an adjustable output circuit, impedance network means responsive to changes in the variable resistance means to develop a feedback voltage of preselected time response characteristics, variable impedance reactor meanshaving a plurality of windings including a primary winding connected in series with a secondary winding, a multi-tapped control winding connected in series to a direct current voltage source and the variable resistance means, said multi-tapped control winding being operable to. control the output impedance of the series connected primary and secondary windings, and a feedback-bias winding connected to adirect current voltage source in series through said impedance network means to operably modify the saturable linx operating characteristics of the reactor means, the input circuit of the rectifier means being connected for excitation to the adjustable output circuit `ofthe transformer means through the series connected primary andv secondary windings of said reactor means, the output circuit of the rectifier being connected in shunt, tothe varying potential responsive means of said regulator, and switch means connected to said multi-tapped control winding and adapted to selectively short circuit av predetermined portion of said multi-tapped control winding for simultaing diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditionsY of yload and speed is simulated to facilitate test of-thervoltage regulator.

8. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having aninputcircuitand anoutput circuit, transformer means having an input circuit connected to an alternating current voltage source and an adjustable outputY circuit, resistive-capacitive network means responsive to changes in the variable resistance means to rdevelop a feedback voltage of preselected time response characteristics, variable impedance reactor means having a plurality of windings including a primary winding connected in series with a secondary winding, a multi-tapped control'winding connected to a direct current source in series'with the resistive-capacitive network means and the variable resistance means, and a feedback-bias winding connected in series with the direct current source through the resistive-capacitive network means to operably modify the saturable flux operating characteristics of the Vreactor means, the input circuit of the rectifier means being connected for excitation to the adjustable output circuit of the transformer means` through the series connected primary and secondary windings of said reactor means, the

' output circuit of the rectifier being connected in shunt to the varying potential responsive means of said regulator, adjustable resistive means connected in shunt with the output circuit ofthe rectifier to adjust for normal operating current traversing the varying potential responsive means, and switch means connected to said multi-tapped control winding and adapted to selectively short circuit a predetermined portion thereof for simulating diverse magnitudes of shock electrical loading and unloading of KVa generator, whereby the dynamic operation of a. generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

9. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means forl controlling the variable resistance means, comprising: rectifier means having an input circle and an output circuit, transformer means having an input circuit connected to an alternating current voltage source and an adjustable output circuit, impedance network means responsive to changes in the variable resistance means to develop a feedback voltage of preselected time response characteristics, variable impedance reactor means having a plurality Vof windings including a primary Awinding connected inseries with a secondary winding, a bias winding connected to a direct current source through a bias control resistance to control the quiescent operating point of the reactor means, a control winding connected in series to a direct current voltage source with said impedance network means and the variable resistance means, said control winding being operable to control the output impedance of the series connectedY primary and secondary windings, and a feedback winding connectedto the impedance network to operably modify the saturable ux operating characteristics of the reactor means, the input circuit of the rectier means'being connected for excitation to the adjustable output circuit of the transformer means through the series connected primary and secondary windings of said reactor means, the output circuit ofthe rectifier beingconnected in shunt to the varying potential responsive means of said regulator, and switch means connected to said control Winding and adapted to select a predetermined portion of said control winding for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

l0. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformer means having an input circuit connected to an alternating currentvoltage source and anfadjustable output. circuit, impedance network means responsive to changesin the variable resist'ancemeans to develop a feedback voltage of` preselectedY timev response characteristics, variable impedance reactor means having a plurality of windings including a primary winding connected in series with a secondary winding, a bias winding connected to a direct current source through a bias control resistance to control the quiescent operating point of the reactor means, a multi-tapped control winding connected to the direct current source in series with the impedance network means and the variable resistance means, and a feedback Winding connected to the impedance network means to operably modify the saturable ilux operating characteristics of the reactor means, the input circuit of the rectifier means being connected for excitation to the adjustable output circuit of the transformer means through the series connected primary and secondary windings of said reactor means, the output circuit of the rectifier being connected in shunt to the varying potential responsive means of said regulator, and switch means connected to said multitapped control winding and adapted to selectively short circuit portions thereof for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the Voltage regulator.

ll. An apparatus for testing a voltage regulator of the type having variable resistance means operably coupled to a varying potential responsive means for controlling the variable resistance means, comprising: rectifier means having an input circuit and an output circuit, transformer means having an input circuit connected to an alternating current voltage source and an adjustable output circuit, resistive-capacitive network means responsive to changes in the variable resistance means to develop a feedback voltage of preselected time response characteristics, variable impedance reactor means having a plurality of windings including a primary winding connected in series with a secondary winding, a bias winding connected to a direct current voltage source through a bias control resistance to control the quiescent operating point of the reactor means, a multi-tapped control winding connected to the direct current voltage source in series with the resistivecapacitive network means and the variable resistance means, and a feedback winding connected to the resistivecapacitive network means to operably modify the saturable ux operating characteristics of the reactor means, the input circuit of the rectifier means being connected for excitation to the adjustable output circuit of the transformer means through the series connected primary and secondary windings of said reactor means, the output circuit of the rectifier being connected in shunt to the varying potential responsive means of said regulator, adjustable resistive means connected in shunt with the output circuit of the rectier to adjust for normal operating current traversing the varying potential responsive means, and switch means connected to said multi-tapped control winding and adapted for selectively short circuiting predetermined portions thereof for simulating diverse magnitudes of shock electrical loading and unloading of a generator, whereby the dynamic operation of a generator under various conditions of load and speed is simulated to facilitate test of the voltage regulator.

References Cited in the le of this patent UNITED STATES PATENTS