US2680832A - Voltage regulating means - Google Patents

Description

.June 8, 1954 B. H. SCHULTZ VOLTAGE REGULATING MEANS Filed Aug. 8, 1949 A fllk IN V EN TOR.

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Patented June 8, 1954 UNITED STATE-S PATENT OFFICE 2,680,832 VOLTAGE REGUI JATING MEANS Blaine H. Schultz, South Milwaukee, Wis., assignor to *McGraw ElectricCompany, acorporationof Delaware Application August 8, 1949,"Serial No.109;1'74

2 Claims. (Cl. 32343.5)

,lThis invention relates to "an automatic regulator control means and is particularly directed to-a means-forcontrolling the voltageof a power line.

In voltage regulating systemspit is the practice to-use a contact making voltmeter to convtrol a-regulating means such as a .tap changing regulator or other device to thereby control the voltage. The voltage responsive :means, 'lnamely the-contact making voltmeter, frequently gives troubleclue to chattering. and burning of thecorn tacts and alsoxdue to-chattering'and burning of the :contacts of any contactor controlled *from the voltmeter.

Thisinvention is designed to overcome the labove'noted defects and objects of this invention are to provide an automatic regulator .control means :in which-a'contact making voltmeter :isemployed and'so associatedwith other portions of the system and apparatus that a seal-in :or holding efiect is produced-to prevent chattering of any of the contacts, either of :the contact making voltmeter-r of any apparatus: controlled thereby, and to provide such a holding effect as hereinabove described'by electrical :means.

Ingreaterdetail, obiectsof this inventionare to 1 provide control means for an automatic regulator whose primary or initiating instrumentalityiis a-lcontact makingvoltmeter which will close azfirst vpair of "contaots'when the voltage lto ibe regulated reaches a predetermined upper limit andwhich will close other contacts when :the voltage to be regulated drops 'to'ailower predeitermined limit and to so arrange :the apparatus that. means are provided for immediately selectively shifting the upper or the lower-limit :as

required so that a newupper limit or a-newlower limit is instantly provided when theiapparatus functions.

Further objects are to providezaunoveltform of contact makingvoltmet-er in. which :thelpo- 'tential coil unit acts in the dual capacity of :a transformer with primary and secondary windings furnishing currentfor current coils and'in which the potential coil unit also actssas 2.2130- tential coil, the flux from both a the I potential and current coils acting on an. induction'disla, in

which the-current in the primary windingsiis mainly the magnetizing current and inwl'ii'ch the current flowing in thesecondary win'dingvhas only azsmall effect on the phase'angle-of thelpri- :mary current with reference'toithe voltage impressed on :the primary-coil.

.An embodiment 0f; the invention is shown in the-accompanying drawings; in which:

consequently tend to rotate the disk 2.

voltage of the, primary primary: and secondary currents in the windings i3 and t rare-not approximately apart, but instead, the-xpotential coil :or :primary :3 :acts

Figure 1 .is adiagrammatic view showing the -aut.omatic-regulatorcontrolmeans.

Figure 2 is a chart showing the relations-between thenormalvoltage and the upper andlower limits and the new upper and lower limits-which latterareestablished by the operation of the device.

'Rcferringto Figure 1 it will-be-seen that the device has been shown as a control means ;for

controlling a tap changing regulator, although it is to be understood that it'could' be used to control any other voltage regulating. means; The

contact making voltmeter is indicated generally by the reference-character I and it will be .seen that it consists of aninduction disk2, a voltage coil '3, and a pairof current coils 4. A damping of nickel; copper and iron, although any suitable thermosensitive alloy could be employed.

The'operation of this magnetic bridge or shunt isto compensate for change influx due to'change in resistance of the "coils as the temperature changes. lltsimode of operationis identically the sameas that in well known watt-hour meters.

It is to'be noted that the voltage coil '3 has wound thereover asecondary .t'which furnishes current to the current coils '4. It will be seen that the flux from the voltage coil 3 and thecurrent coils '4 have a different phase angle and In =.the illustrationchosenythe tendencyof the disk is tozrotat'e in a counterclockwise direction but this is resisted by means of a spring l whichtends to rotate the disk. in a clockwise direction. The spring isvattach'edto the shaft i of the-disk 2 vwhich shaft earries the lmovable contact 9 which is adapted toselectivelyxengage contact Hlwhich may be termed-the upper voltage or upper limit conta ct. or-a contact ii, which-may be'termed -the lower voltageor lower limit contact.

A particularly important feature of thecontact making :i oltrueter itself is that the current flowing in the secondary hassubstantiallyno efiectvon the phase angle hetweenthe current and in other words; the

mainly as an inductive load and the current in such coil is primarily the magnetizing current of the inductive load.

It will be seen that the primary and secondary windings 3 and 6 and their magnetic core, not shown, constitute a transformer, T, forming a unitary part of the contact making voltmeter and having a high value of primary leakage flux. This transformer T, therefore, performs a dual function and not only acts as a transformer having the characteristics enumerated, but also acts,

in effect, as the potential coil unit of the contact making voltmeter.

The potential coil 3 is fed from the secondary of a potential transformer l2 which is connected across the line 13 whose voltage is to be regulated. The line 53 goes to the load and is supplied from the mains 14 through a tap changing regulator indicated generally at 5. The tap changing regulator is provided with a plurality of taps E6 on its primary side, any one of which may be engaged by the movable contact H, such latter contacts being driven from a reversing motor iii in any suitable manner through reduction gears, not shown, if desired.

It is to be understood that the movable contact I7 is insulated from the driving mechanism and the movable contact 9 is insulated from the shaft 8.

It is to be noted that the secondary of transformer it supplies the lines l 9 and 20 and that the reversing motor has one terminal, for instance the terminal 2 l, permanently connected to the line I9. One of the other terminals 22 is connected to the contact 23 of a contactor indicated generally at 24 which may be called the upper voltage contactor. The corresponding contactor of the contactor 24 is connected to the other line 26 supplied from the transformer 52. Normally this circuit is open and the motor is idle. Another terminal 26 of the reversing motor i8 is connected to a contact 2'5 of the contactor indicated generally at 28 which may be called the lower voltage contactor. The corresponding contact 29 is connected to the line 29 supplied from x the transformer 52. The arrangement of the motor S8 is such that when the circuit is closed by the movable contact 3?; of the upper voltage contactor 24, that the motor runs in such a direction to lower the output voltage from the tap changing regulator and when the circuit is closed by means of the movable contact 3! of the lower voltage contactor, the motor runs in such a direction as to raise the output voltage of the tap changing regulator l5.

It is to be noted from an examination of Figure 1, that three resistors 32, 33, and 34 are connected in series with the potential coil 3 of the contact making voltmeter l The resistor 34 is a potentiometer type resistor and may be adjusted so that the contact making voltmeter can regulate or control. at different voltage levels. Obviously the resistors 32 and 33 may also be of the potentiometer type if so desired or they may be fixed resistors as shown. It will be seen, as the description proceeds, that the cutting out and cutting in of the resistors 32 and 33 produces a holding or lock-in effect and also determines a new upper and a new lower voltage limit.

It is to be noted that normally the resistor 33 is shorted out by means of the movable contact 35 of the lower voltage contactor 23 and that the resistor 32 is normally in series with the potential coil 3 of the contact making voltmeter and is shorted out only when the contactor 24 op the crates. This shorting out of the resistor 32 is accomplished by means of the movable contact 35 of the upper voltage contactor 24.

It is to be noted that the contactors 2i and 28 are provided with magnetic plungers 3? and 38, respectively, which are adapted to be drawn downwardly, in the form illustrated, into their energizing coils 39 and 40 when the circuits of these coils are selectively closed by the contact making voltmeter. Each contactor is biased so as to remain normally in the position shown in Figure l and is moved from this position to its lowermost position when it is energized.

It is to be noted that the energization of the coil 39 of the upper voltage or upper limit contactor 24 occurs when the movable contact 9 of the contact making voltmeter l engages the stationary contact iii and that energization of the coil 49 of the lower voltage or lower limit contactor 28 occurs when the movable contact 9 of the contact making voltmeter engages the stationary contact II.

The operation of the apparatus is as follows:

Assume that normal voltage exists between the mains l3. This is represented in Figure 2 by means of the full line N. Under these conditions, the torque exerted on the induction disk 2 of the contact making voltmeter just balances the force of the spring 'i to hold the movable contact 9 in its neutral or approximately middle position. If it is assumed that there is a voltage rise, for example to the upper limit indicated in Figure 2 by the full line U, the contact making voltmeter operates to close its upper limit upper voltage contacts, that is to say to move the movable contact 9 into engagement with the stationary contact ill, the torque on the induction disk 2 overcoming the force of the spring 7. As soon as the contact 5 engages the contact Hi, the upper limit contactor shorts out the resistor 32, placing a higher voltage on the voltage coil 3 of the contact making voltmeter and materially increasing the torque exerted on the disk 2 and thereby sealing in or holding in the upper limit contacts of the contact making voltmeter or, in other words, holding the movable contact 9 more firmly against the stationary contact Hi. This prevents any possible chattering and burning of either the contacts 9 and ID of the contact making voltmeter and any chattering and burning of the contacts of the upper limit contactor 2%, It will now be found that the device has established a new and lower upper limit or upper voltage level indicated in Figure 2 by the dotted line U1. The motor it; operates to lower the voltage controlled by the tap changing regulator l5, but this voltage must now be lowered below the new upper limit U1, see Figure 2. When this occurs, the contact making voltmeter operates to open its upper limit con tacts and immediately the upper limit contactor 24 opens and reinserts the resistor 32 in series with the potential coil 3 of the contact making voltmeter I and thus re-establishes the old or initial upper limit U, see Figure 2. It is apparent, therefore, that there can be no chattering and burning of the contacts of the contact making voltmeter and those of the upper limit contactor 24.

If the voltage drops to the lower limit indicated at L in Figure 2, the contact making voltmeter operates to close its lower limit contacts or lower voltage contacts by causing the movable contact a to engage the stationary contact Ii. The lower limit contactor 28 immediately oper- S ates and inserts the resistor 33 in series with the potential coil 3 of the contact making voltmeter and thus establishes a new and higher lower limit L1, see Figure 2. The motor I8 in this instance operates in such a direction as to raise the voltage impressed on the line [3. The insertion of the resistor 33 in series with the potential coil 3 of the contact making voltmeter I seals in or holds in the lower limit contacts of the contact making voltmeter and consequently prevents chattering and burning of these contacts and those of the lower limit contactor 28.

It will be seen that a novel form of automatic regulator control means has been provided in which there can be no chattering or burning of the contacts of either the contact making voltmeter or of the contactors controlled thereby. It is to be noted further that an automatic seal-in or holding effect is produced by electrical means by the insertion or removal of the resistors in series with the contact making voltmeter, thereby establishing a new upper or a new lower limit as required.

It will also be seen that a time delay effect is provided by the drag magnet of the contact making voltmeter and that the device will not respond to transient fluctuations but will respond to a change in voltage which persists a predetermined length of time.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. Means for regulating the voltage of an electric line comprising adjustable voltage varying means for varying the voltage of said line, motor means for adjusting said voltage varying means, a contact making voltmeter having means including a coil supplied from said line and contact means having a first and a second position corresponding to an increase or decrease in line voltage, respectively, and arranged to connect said motor means with a source of power to thereby operate said voltage varying means to respectively lower or raise the voltage impressed on said line, and means controlled by said contact making voltmeter for respectively raising or lowering the voltage impressed on said coil when said contact making voltmeter occupies said first or said second position independently of the action of said voltage varying means and independently of said motor means.

2. Means for regulating the voltage of an electric line comprising adjustable voltage varying means for varying the voltage of said line, motor means for adjusting said voltage varying means, a contact making voltmeter having means including a coil supplied from said line and contact means having a first and a second position corresponding to an increase or decrease in line voltage, respectively, and arranged to connect said motor means with a source of power to thereby operate said voltage varying means to respectively lower or raise the voltage impressed on said line, a first resistor normally connected in series with said coil, a second normally ineffective resistor, and contactor means controlled by said contact making voltmeter for respectively shorting out said first resistor or placing said second resistor in series with said coil when said contact making voltmeter occupies said first or said second position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,250,806 Craighead Dec. 18, 1917 1,516,313 Searing Nov. 18, 1924 1,743,096 Bergvall Jan. 14, 1930 2,022,537 Champlin Nov. 26, 1935 2,079,492 Courtin May 4, 1937 2,200,128 West May 7, 1940 2,296,031 Hall Sept. 15, 1942

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