US2302889A - Voltage regulator - Google Patents

Description

INov. 24,1942. 1 G, REED 2,302,889

VOLTAGE REGULATOR Filed April 5, 1939 REVERS/SLE M0701@ INVENTOR. JSEP/-l GR/FF/THS REED ATTORNEY.

Patented Nov. 24, 1942 2,302,889 VOLTAGE REGULATOR Joseph Griiiiths Reed, Croydon, near Sydney, New

Southj Wales, Australia, asslgnor to Radio Corporation of America, a corporation of Delaware Application April 5, 1939, Serial No. 266,041 In Australia April 26, 1938 3, Claims. (Cl, 171-312) This invention relates to automatic voltage regulating devices, and more particularly to control apparatus therefor.

Automatic voltage regulators of the type to which this invention relates usually employ a two-day contact making relay (hereinafter referred to as the regulating relay) which is coupled to the circuit whose voltage is to be controlled, in such a manner that when the voltage of thesaid circuit is of the desired value a moving arm, or tongue, arranged to close the contacts of the regulating relay` is in the neutral position.

If. in the aforesaid type of regulators, thefcircuit voltage varies above or below the predetermined value, the tongue of the regulating relay will touch one or other'of its co-operating contacts, according as to whether the voltage in the said circuit rises or falls, and bring into service a switching relay controlling reversible means whereby an induction regulator or an equivalent power regulating device is operated to cause the voltage in the regulated circuit to be increased or decreased and thus restored to its normal or approximately normal value.

If the above mentioned regulating relay controlled the aforesaid reversible means directly, the latter would cut out immediately the contacts on the regulating relay separated. This would cause erratic operation due to chattering contacts on the regulating relay, not to mention contact deterioration due to inevitable sparking which would be caused by the slow break.

One of the objects of this invention is to overcome both of the above disadvantages, ensuring (a) an almost currentless circuit for breaking by the regulating relay, and (b) a time delay ensuring continued operation of the regulating means for a predetermined interval, sufficient to bring the tongue of-the regulating relay to the normal neutral position instead of keeping it just clear of one or other of its contacts and thus maintaining the voltage at the upper or lower limit of regulation.

Various methods have been suggested from time to time for achieving these objectives, but the nature of the majority of them renders the constructions involved very expensive and thus uneconomical for general use.

It is therefore a further object of this invention to provide an improved automatic voltage regulator control arrangement which is simple in design, efficient in operation and comparatively inexpensive to manufacture.

According to this invention automatic control apparatus is interposed between the regulating relay and the reversible means governing operation of the induction regulator or its equivalent. The said automatic control apparatus has an operating time constant such that the said reversible means is maintained operative until the tongue of the regulating relay .returns to the neutral position.'

In order to obtain a clearer understanding of the invention and the manner in which it operates, reference should now be made to the accompanying drawing which forms part of this specification. The said drawing illustrates one way of carrying out the invention.

In the said drawing 2 is an electron discharge tube, constituting a thermionic relay device having a twin arrangement of triode elements and comprising a single indirectly heated cathode 5, separate anodes 4, 4', and' separate control grids 3, 3. The elements 5, 3 and 4 together form one triode section, whilst the elements 5, 3' and 4' form the second triode section.

The triode sections function in a manner similar to separate discharge tubes and, whilst the arrangement shown is preferred for the sake of simplicity and cheapness in construction, it will be understood that separate triode discharge tubes may be used in place of a single valve such as 2 without departing from the nature of this invention.

The anodes 4, 4 are connected through the energising windings of switching relays 6 and I respectively to a common conductor 35 joined to the high potential side of the secondary winding I2 of a power transformer III connected to the alternating current supply mains 34.

The power transformer I0 has a primary winding II and separate secondary windings I2 and I4. The secondary winding I2, as already stated, provides the operating potentials for the anodes v4 and 4'; the secondary winding I4 provides the energising current for the heater of the indirectly heated cathode 5, whilst section I3 of the winding I2 is-connected to the rectier I5 which supplies biasing potentials for the grids 3 and 3 through time delay networks-31 and 36 respectively.

The diode rectifier I5 is connected in series with the load resistor I 6 across the section I3 of the secondary winding I2. The load resistorIt has a filter condenser I'I connected inv parallel with it to smooth out the pulsations inthefrectined current potentials developed across the load resistor I5. u

The grid 3 of the valve 2 is tolthel point 3s of the 10aa resistor Is, throughs time delay network comprising series resistors 23, 24 and parallel connected capacitors 25, 28, whilst the grid 3' is connected to the point 38 of the load resistor i6 through a time delay network comprising series connected resistors I9, Il and parallel connected capacitors 2|, 2l.

The grid 3' has an additional connection through resistor 22 to one contact 32 of a regulating relay 28, and the grid 3 is connected to an oppositely disposed contact 3l of the relay 28 through a resistor 21. Interposed between contacts 3| and 32 of the relay is the moving arm or tongue 30, which is connected to the cathode lead 39, which may be earthed.

The switching relays 6 and 1 connected in series with the anodes l and l respectively may be of any well known type and serve to control switches 8 and S respectively of a reversible driving means 52 governing operation of an operable voltage varying device which may be an induction regulator or its equivalent.

It may be assumed, for the purpose of explaining this invention, that the operable voltage regulator 5i or the like is operated by the reversible motor 52 and that when contacts 8 of switching relay 6 are closed, the said motor will rotate in one direction, whilst when the contacts 9 of the switching relay 1 are closed the direction of rotation of the motor 52 will be reversed.

The regulating relay 28 is arranged to be energized by the circuit to be regulated, that is to say, it is on the regulated side of the voltage regulator. It is assumed that device 52 is interposed between the voltage source and the voltage utilizing device 50.

With the tongue 30 of the relay 28 inthe neutral position, the grids l, 3' of the valve 2 are supplied with a negative potential from the load resistor I6 of the bias rectifier l5. The value of the negative potential applied to the grids is such as to block the current flowing in the anode circults.

A movement of the tongue 30 to one contact will earth the grid of the particular side of the valve 2, causing anode current to ilow in the corresponding anode circuit. This current closes the relevant switching relay, thus operating the reversible motor coupled to the induction regulator. 'I'his causes the said regulator to raise or lower the voltage of the regulated circuit, according to the direction in which the said motor is driven.

Variation oi the controlled voltage as a. result of the operation oi the induction regulator or its equivalent will almost immediately cause the tongue 30 of the relay 28 to leave the contact previously engaged. If this relay 28 controlled directly the switching of the reversible motor coupled to the regulator, the motor would stop so soon as the tongue 30 of relay 28 breaks contact.

The present invention guards against the latter possibility by providing resistance capacity' time delay circuits 36 and 31 for the respective grid circuits of the valve 2. This means that normal bias is not restored on either grid until a short interval has elapsed depending on the time constant of the resistance capacity network in each grid circuit. This time constant can be made such as to maintain anode current and consequent closure of motor control relays i or 1 until the regulated voltage rises or falls to a value corresponding to the neutral position of the tongue 30 of relay 2l. From the foregoing it will be seen that when the line voltage rises or falls beyond the predetermined limits. the regulator will operate until the voltage is restored to the normal condition. Consequently, the voltage will not iiuctuate erratically in the vicinity of the upper and lower limits of regulation as would be the case without the time delay feature of this invention.

` Although the invention has been described in connection with a circuit arrangement which derives 'its operating potentials from alternating current supply mains, it is to be clearly understood that the arrangement is equally applicable to sources of direct current potential. The moditications necessary to adapt the apparatus for direct current operation will be readily appreciated by those skilled in the art. and further explanation in this connection is considered unnecessary.

What is claimed is:

1. In a voltage regulating system, a voltage controlling means, a pair of operable relays one thereof acting upon operation to cause said means to increase the regulated voltage and the other thereof acting upon operation to cause said means to decrease the regulated voltage. a pair of space discharge devices each thereof having an anode, a cathode, and a grid electrode, means for energizing said cathodes, an anode circuit and a grid circuit for one of said space discharge devices, said anode circuit including one of said relays and a source of space current, said relay being adapted to be operated by the space current of said space discharge device, said grid circuit including a time delay circuit and means for normally biasing said space discharge device to cut oi! through said time delay circuit, an operable switching means acting upon operation to remove the cut oi! bias from said space discharge device whereby the relay in its anode circuit is caused to operate, an anode circuit and a grid circuit for the other of said space discharge devices, said last named anode circuit including the other of said relays and a source of space current, said last named relay being adapted to be operated by the space current of said last named space discharge device, said last named grid circuit including a time delay circuit and means for normally biasing said last named space discharge device to cut of! through the last named time delay circuit, a second operable switching `means acting upon operation to remove the eut oif bias from the last named space discharge device whereby said last named relay is caused to operate, means responsive to fluctuations of the regulated voltage, said last named means acting to cause the operation of one of said switching means when the regulated voltage is above the correct value and the other of said switching means when the regulated voltage is below the v V correct value.

2. In a voltage regulating system, a voltage controlling means, a first operable relay device acting upon operation to cause said means to increase the regulated voltage, a second operable relay device acting upon operation to cause said means to decrease the regulated voltage, a first space discharge device having an anode, a cathode, and a grid electrode, means for energizing said cathode, an anode circuit and a grid circuit for said space discharge device, said anode circuit including said first relay and a source of space current, said iirst relay being adapted to be operated by the space current of said space discharge device, said grid circuit including s time delay circuit and means for normally biasing said first space discharge device to cut oi! through said time delay circuit, s, rst operable switching means acting upon operation to remove the cut off bias from said rst space discharge device whereby said first relay is caused to operate, a second space discharge device having an anode, a cathode, and a grid electrode, means for energizing said last named cathode, an

anode circuit and a grid circuit for said second space discharge device said last named anode circuit including the second relay and a source oi' space current, said second relay being adapted to be operated by the spacev current oi.' they second space discharge device, said last named grid circuit including a time delay circuit and means for normally biasing said second space discharge device to cut on' through said second time delay circuit. a second operable switching means acting upon operation to remove the cut oir bias from said second space discharge device whereby said second rel-ay is caused to operate, means responsive to fluctuations of the regulated voltage, said last named means acting to cause the operation of the ilrst switching means when the regulated voltage is below the correct value and the operation of the second switching means when the regulated voltage is above the correct value.

3. In voltage regulating` system, an operable voltage controlling means, a pair oi.' operable relays one thereof acting upon voperation to eiect the operation of said controlling means so as to cause a change in the regulated voltage in one direction, the other acting upon operation to effeet the operation of said tlrst named means so as to cause a change in the regulated voltage in the opposite direction, a pair of space discharge devices each thereof having an anode, a cathode, and a grid electrode, means for energizing said cathodes, an anode circuit and a grid circuit for one of said space discharge devices, said anode circuit including one of said operable relays and a source of space current, said grid circuit including a time delay circuit and means for biasing said space discharge device through said time delay circuit, an anode circuit and a grid circuit for the other of said space discharge device said last named anode circuit including the other of said relays and a source of space current. said last named grid circuit including a time delay circuit and means for biasing said space discharge device through said time delay circuit. means responsive to voltage fluctuations of the regulated voltage comprising a three-position device arranged so that when the regulated voltage is at the proper value, the relay assumes a neutral position, whereas when the regulated voltage is above the proper value the relay assumes a second position and when below the proper value, the relay assumes a third' position, means including said voltage responsive means for controlling the operation of said space discharge devices, said two space discharge devices being initially biased so that said operable relays have no effect upon said voltage controlling means when said voltage responsive means is in its neutral position, said voltage responsive means acting when in its second position to change the bias applied to one of said space discharge devices and thereby cause the operation of one of said operable relays whereby said tlrst named means causes a change in the regulated voltage in a direction to re-establish the correct voltage, said voltage responsive means acting when in its third position to change the bias applied to the other oi' said space discharge devices and thereby cause the operation of the other of said operable relays whereby the first named means causes a change in the regulated voltage in a direction to reestablish the correct voltage, said initial biasing o! the space discharge devices being re-established when the desired voltage is re-established, each of said time delay circuits having sumcient time delaying characteristics to maintain its operable relay in operation for a period of time suflicient to assure the return of said vvoltage responsive means to its neutral position before said first named means is rendered inoperative by the re-establishment oi' the desired voltage.

JOSEPH GRIFFI'IHS REED.

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