US2666860A - Automatic control means - Google Patents

Description

w. J. WEINFURT ET AL 60 AUTOMATIC CONTROL MEANS Filed Dec. 30,- 1950 INL ENTORS /eznfuri .1 4i Bale J filh fraA jfI/arney Patented Jan. 19, 1954 AUTOMATIC CONTROL MEANS William J. Weinfurt, Wauwatosa, and Alton G.

Bale, Jr., Milwaukee, Wis., assignors to Me- Graw Electric Company, Milwaukee, Wis., a

corporation of Delaware Application December 30, 1950, Serial No. 203,697

4 Claims.

This invention relates to automatic control means and is particularly directed to a means for controlling a plurality of switches, which latter may be adapted for throwing in or cutting out a bank of capacitors in a three phase distribution line.

Objects of this invention are to provide a contact making voltmeter for controlling the various elements or the system so as to cause the controlled switches to close or open in accordance with voltage variations, and to so arrange the device that there will be no chattering of the contact making voltmeter or of the relays controlled thereby, but in which the component parts of the control system are so arranged that upon a voltage drop they will immediately lower the voltage further to produce a seal-in or hclding effect and similarly when the voltage rises, they will increase the voltage impressed on the contact making voltmeter and thus provide a seal-in or holding eiiect for a rise in voltage.

In greater detail, objects of the invention are to provide a control means for the simultaneous control of a plurality of switches whose primary or initiating instrumentality is a contact making voltmeter which will close a first pair of con tacts when the voltage to be regulated reaches a predetermined upper limit and which will close another pair of contacts when the voltage to be regulated drops to a lower predetermined limit,

and to so arrange the apparatus that means are provided for immediately selectively shifting the upper or lower limit as required, so that a new upper limit or a new lower limit is instantly provided when the apparatus functions.

Further objects are to provide a control means [for controlling the operation of a plurality of switches which control means includes a time delay means so arranged that it is initially set in operation by a relay controlled from the contact making voltmeter and which establishes an auxiliary circuit for a holding relay for maintaining the control circuit to the motors of the motor control switches closed until they complete one cycle of operations, but which opens the circuit of the time delay means so that the time delay means will immediately reset itself, the time delay being adjustable so that any desired time interval may be obtained.

Further objects are to provide time delay r means so as to reduce the number of operations to a reasonable figure, so that the voltage control means does not function for every minute fluctuation in voltage, but which functions and sets the time delay means in operation with the control of the switches being thereafter removed from the control of the contact making voltmeter until the voltage varies in the other direction a predetermined amount.

An embodiment of the invention is shown in the accompanying drawings, in which the single figure shows diagrammatically the automatic control means.

Referring to the drawings, it will be seen that a contact making voltmeter has been indicated generally by the reference character I. This contact making voltmeter is energized from the secondary 2 of a step-down transformer 3. The primary 4 is connected to the power line whose voltage is to be controlled. The secondary circuit includes a grounded side 5 and a live side 6, and extends through the primary 1 or voltage coil of the contact making voltmeter. This voltage coil and a pair of current coils 8 are displaced and act upon the induction disk 9 of the contact making voltmeter. A damping magnet 5' is positioned as shown to retard the rotation of the induction disk 9 and preferably a magnetic shunt I0 is positioned between the current coils, the magnetic shunt being composed of a thermosensitive alloy such as is commonly employed in watt-hour meters. A customary material is an alloy of nickel, copper, and iron, although any suitable thermosensitive alloy could be employed. The purpose of the magnetic bridge or shunt is to compensate for change in flux due to change in resistance of the coils as the temperature changes, its mode of operation being identically the same as that in well known watthour meters.

The voltage coil 1 has wound thereover a secondary II which furnishes current to the current coils 8. It is to be noted that the flux from the voltage coil 1 and the flux from the current coils 8 have a different phase angle and consequently tend to rotate the disk 9.

An important feature of the contact making voltmeter itself is that the current flowing in the secondary II has substantially no effect on the phase angle between the current and voltage of the primary 1. In other words, the primary and secondary currents in the windings l and II are not approximately 180 apart, but instead the potential coil or the primary coil 1 acts 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 l and II and their magnetic core, not shown, constitute a transformer indicated genon a shaft indicated by the dotted line l2 and:

the shaft at its lower end carries a. movable contact I3 which is insulated from the shaft. This movable contact is providedawith a helical spring II which tends to hold it in neutralpositioneentrally between the stationary contacts and lss is deenergized. The motor has a reduction mechanism and drives a movable contact arm or member 28 into engagement with the stationary contact 28. It is returned by means of a spring 36 when the motor 26 is deenergized as the clutch immediately opens and allows the contact arm 28 to swing" back to the adjustable stop 3| without operatingthemotor. The adjustable stop 3| determines the time interval before the movable contact arm 28 engages the stationary contact 7 29 and thus determines the amount of time delay.

The movable contact is connected as indicated at H to the grounded side 5 of the; secondary circuit of the transformer 3.

It is to be noted that one side of the secondary circuit 5, 6, from the transformer 3 is provided with .a pair. of resistances I8 and [9 whose effect is. controlledrrespectively by thexlow voltage relay or contactor and theihigh voltage relay or contactor 2|. Normally the. resistor I8 is bridged by thelupper movablecontact 22 of the contactor to be noted also that a-manually adjustab1e-vari able resistor-24 is placed in series. with the primary-"l; so. thatt-he normal voltage. point may be predeterminedbythe setting of the adjustable resistor 24.

It is apparenathat-whenthevoltage falls, that the movable; contact I 3 of the contact making. voltmeter will engage the stationary contact It and will ,thus close the. energizing circuit of the low voltage contactor or relay 20. This will cause, such'icontactor to close and thereby place the; resistor l8 in series with the voltage coil 1 of thecontact making voltmeter and thereby produce a further drop in voltage providing thereby a seal-in voltage for holding the contact-.makingvoltmeter movable contact I 3 in firm engagement with the stationary contact 16.

On the other hand, if the: voltage rose, the contactlmaking voltmeter movable contact US would engage the stationary contact l5 and would thus energize the high voltage relay or-contactor 2|, thus causing it to close. The closing of the relay 2| shorts. the resistor 89. and causes a. highervoltage to be impressed on the voltage coil 7- of the. contact making voltmeter thus providing a seal-in voltage.

The contact making voltmeter as thus far de.-. scribed, maybe of the same general typeasthat previously described in the .copending application of Blaine Schultz, for Voltage Regulat--v ingLMans, Serial No. 109,17 4, filed August 8, 194 .9, and assignedto the sanieassignee asthepresent invention.

A time..delayunitindicated :generallyby the reference character25 .is provided-and is controlled. fromthe contactor 2G or ZI -depending upon which is energized. Thistime delay means 25 "consists of a self-starting, synchronous motorv 26 which has a normally open magnetically'clos'ed clutch 21"Which is closedwhen the motor 261s energized and .which is released. when the motor Assume that the contactor 23 has operated. Thecontact 32 ofsuch contactor closes the circuit through' the conductors 33 and 34 and the movable contact 35 of a holding or by-pass relay 36 to themotor 25 and the motor, therefore, starts tooperate. After the desired interval of time has elapsed, the movable arm 28 of the time delay device engages the stationary contact 29 and closes the circuit through the energizing coil of the holding'relaytfi causing the holdinglr'elay to moveto the upper position as viewed inithe drawings. Whentheholding re1ay36 is enerl-x gized, it establishes a holding circuit'independ ently ofthe time delay device 25 and also deene ergizes the motor 26 of the timedelaycdevice allowing the movable arm 28 to immediately move away from the stationary contact 29 into engagement with the stop 31. At the same time the holding relay also establishes a holding 1511":- cuit for itself, as its movable contact 35 now connects the upper end of the coilrstwwith the conductor 3 and through the. contact :32 of the low voltage relay 23 with the grounded side :5101 the secondary circuit. The lower side ofitheenergizing coil of the holdingirelay 36 is connected to the live side 5 of the secondary circuit: Thus the timedelay motorZfi is not energizedand instead the holding relay remains energized until the contactor20 drops open. The .contactorior low voltage relay 20 also causes its lower contact alto connect the stationary contactsta of the selector switch 39 of each of the; motorzdriven switches indicated generally by the reference character 40 through themovable contact 35 of the holding. relay 36, while in its upper position, and the contact 32 of the low voltage; contactor or relay 20 to the grounded side Eof the secondary circuit. The motors 4| are each connected tothe corresponding-selector switch Hand to the live side 6 of the secondary circuit.

As soon as the motors start to operate, they move their holding switchesM'to the contacts 43 which establish an additional connection from each of the motors to the. grounded side 5. of the secondary circuit so that the motors continueto operate irrespective of any. action of the; relays. This holding circuit is broken by motion of the holding switches 42 when the motors complete their cycle of operations and move their selector switches 39 to the-0th er contact 44. At this time the motors stop functioning since the holding switch 42 moves to open position when the mo-f tors have completed their cycle of operations. This cycle of operations of the motors closes their driven switches 45 which in turn control capacitors or any other means, not shown.

When the selector switches 39 are in engage.- ment with the stationary contacts 44, it will be seen that the motors cannot be energized until the high voltage contactor or relay 2! closes; The "operation of the' high voltage relay or con.- tactor is exactly. thelsame as. that previously deescribed for the low voltage relay or contactor '20 except forthe fact. that instead of placing; a re-.

sister in series with the contact making voltmeter, it shorts out its resistor l9 and thus produces the hold-in voltage of a higher value than that for which the contact making voltmeter responded.

In the cycle of operations of the motors 4! for opening the switches 45 their holding switches 42 close when the motors start to operate and stay closed until the motors have approximately completed their cycle of operations for opening the driven switches 45. When the motors have completed the opening of the switches 45, the selector switches 39 are moved to their first position as shown in the drawings.

It will be seen that a novel form of automatic control means has been provided in which any desired time delay may be obtained by suitably adjusting the time delay means. After the time delay means has served its purpose, it is deenergized and is taken out of circuit, the holding relay then having established its circuit independently of the time delay means.

It will be seen further that the contact making voltmeter does not carry the current for energizing the driving motors of the control switches but that these motors are controlled from the contactors or relays.

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.

We claim:

1. Automatic control means comprising a plurality of independent driven switches, a driving motor for each of said driven switches, a, first and a second contactor for simultaneously controlling said motors for respectively closing and opening said switches, a power line, a contact making voltmeter controlling said contactors and responsive to voltage variations in said power line, said contact making voltmeter controlling the selective energization of said contactors, a single time delay means for delaying the operation of all of said motors, and a holding relay controlling the operation of said motors and causing deenergization of said time delay means after said time delay means has functioned.

2. Automatic control means comprising a plurality of independent driven switches, a driving motor for each of said driven switches, a first and a second contactor for simultaneously controlling said motors for respectively closing and opening said switches, a power line, a contact making voltmeter controlling said contactors and responsive to voltage variations in said power line, said contact making voltmeter controlling the selec-' tive energization of said contactors, a single time delay means for delaying the operation of all of said motors, and a holding relay controlling the operation of said motors and causing deenergization of said time delay means after said time delay means has functioned, said holding relay being controlled from said time delay means and arranged to form a holding circuit independently of said time delay means after said time delay means has functioned.

3. Automatic control means comprising a driven switch, a driving motor for operating said switch, a first a second contactor for controlling said motor for respectively closing and opening said switch, a contact making voltmeter controlling said contactors, a power line, means operatively connecting said voltmeter to said power line whereby said contact making volt meter will cause the selective energization of one or the other of said contactors in response to voltage drop or voltage rises in said power line, and means controlled by said first and second contactors for increasing the variation of the voltage impressed on said contact making voltmeter in the same sense as the variation in line voltage which caused operation of said contact making voltmeter.

4. Automatic control means comprising a driven switch, a driving motor for operating said switch, a first and a second contactor for controlling said motor for respectively closing and opening said switch, a contact making voltmeter controlling said contactors, a power line, means operatively connecting said voltmeter to said power line whereby said contact making voltmeter will cause the selective energization of one or the other of said contactors in response to voltage drop or voltage rises in said power line, a first resistor arranged to be placed in series with said contact making voltmeter by said first contactor upon dro in line voltage, and a second resistor normally in series with said contact making voltmeter and arranged to be shorted by said second contactor upon rise in line voltage.

WILLIAM J. WEINFURT. ALTON G. BALE, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 16,383 Moss et al July 13, 1926 1,798,704 Ross et al Mar. 31, 1931 2,280,766 Bronaugh Apr. 21, 1942 2,506,282 -Sillers May 2, 1950 2,534,902 Cuttino Dec. 19, 1950

Images