US2198736A - Voltage regulating relay - Google Patents

Description

April 1940- E. D. T. NORRIS ET AL 2,198,736

' V LTAGE REGULATING RELAY Original Filed Feb. 4, 1938 N- Ne wkan,

Inuenlr 'S Patented Apr. 30, 1940 UNITED STATES PA EN OFFICE 2,198,788 vouraor: anopmmof Eric Douglas, Tobias Norris and Norman Newton,

Hoilln wood, England, assignors to Ferranti Electric Inc., New York, NtY.

Original application February 4, 1933, Serial No. 188,808. Divided and this application Novemher 4, 1938, Serial No. Britain February 12, 1937 (Cl. 171-119) p corrects the voltage in a shorter time than that 2 Claims.

tions in spite of voltage variations on the inputv side; in'other cases it is desirable that the voltage regulator should not only correct for the supply voltage variations but it should also cause the output voltage to rise in a'predetermined manner with increase of load.

Various types of voltage regulators for the above purposes are known, e. g., induction regulators, on-load tap-changing boosters and moving coil regulators.

When the voltage correcting function is being performed, it is desirable that the operation should be carried out as quickly as possible, and a regulator which operates instantaneously would be ideal for the purpose.

Automatic operation is at the present time obtained according to one system by means of a voltage sensitive contact-making voltmeter which controls a contactor and auxiliary relays, which in turn start a motor operating the voltage regulator. In another known system, the voltage regulator is controlled by means of a servo-motor operated by a balanced oil-pressure system. In neither system is very high speed operation attainable, so that the response to voltage flactuations falls far short of the ideal.

, nism, i. e., mechanism serving to effect a change in voltage on the output side of the voltage regulator.

The invention is particularly suitable for use in conjunction with the moving coil regulator described in United States specification No. 1,901,768, in which case the current to the motor driving the moving coil is directly controlled by the regulator. By suitable choice of gearing and of the power of the driving motor any desired high speed of operation may be obtained. It is possible, however, for the speed ofoperation to become so high that the operating mechanism 238,884. In Great taken by the relay to reset and there is then a likelihood that the operating mechanism will over-run and change the output voltage beyond the desired limit before the contact-making voltmeter is able to reset and stop the motor. Under these conditions .the contact-making voltmeter -will then operate again but in the reverse direction; the cycle will thus be repeated and the regulator will hunt continually.

The object of the present invention is to provide improved or simplified means for resetting the contact-making voltmeter in a time which is comparable withthat occupied by the operating mechanism in adjusting the output voltage to a desired value.

In practice, it is found that when means are adopted to reset the contact-making voltmeter quickly, the mechanical force exerted on the contact-making voltmeter armature by these means is liable to cause the contact-making voltmeter armature to over-run and make contact in the reverse direction. Hence it is desirable to associate means with the contact-making voltmeter either for preventing or for rendering innocuous such an over-run of the contact-making voltmeter. Such means ,form the subject oi.

U. S. A. application No. 188,808 from which the present application is divided.

The present invention consists briefly in the provision, in an automatic voltage regulator comprising mechanism for adjusting voltage to a deconnections between the secondaries of said transformers and an electromagnetic winding of said contact-making voltmeter and an impedance in parallel with each secondary.

The accompanying diagrammatic drawing illustrates one convenient arrangement embodying the present invention in one form.

The invention will now be described as applied in one form by way of example to a voltage regulator embodying an astatic voltage contactmaking voltmeter hereinafter referred to as a relay comprising an enclosed type mercury switch a embodying a centre connection joined to terminal b and two side contacts c d. The switch is carried on a bell-crank lever e pivoted at I and actuated by the pull on the plunger 0 by an electromagnet coil vo. The electromagnet is of known form such that the pull on the plunger by the electromasnet is substantially independent of the displacement of the plunger throughout its working range. A reversible electric-inducticn motor h embodies two windings i and i so arranged in conjunction with a condenser 2 that when one is energised the motor turns in one direction and eflects movement of a short-circuited coil in a voltage adjusting device It for voltage regulation.

When the other winding is energised the motor reverses and moves the short-circuited coil of the device It in the opposite direction.

Two resistances 3, I, are connectedin series with the operating coil 0 of the relay. These resistances are respectively connected also across the secondary windings 5, I of two current transformers of which the primary windings I, I are connected in series respectively with the actuating coils j, i of the motor h.

In operation when the voltage falls below the predetermined limit, the relay closes the contacts 0, p in the increase" direction. Simultaneously, current flows through the primary winding 8 and motor actuating coil i, the direction of the wind ings t and I and of the currents through them being such that the potential generated by the secondary winding Q assists that applied from the line to the operatingcoil o of the relay. 'Ihe relay is thus caused to reset very quickly. Similarly, when the relay is operated by the line voltage exceeding the predetermined upper limit,

the second current transformer coils l, 1 and -nism and. an electromagnetic contact-making voltmeter for actuating said mechanism, means for resetting said contact-making voltmeter in a time comparable with that occupied by said operating mechanism in performing said adjustment of voltage comprising two transformers the primaries of which are in series with said motor, a two-way switching device operated by said contact-making voltmeter for controlling energisa- I tions between the secondariesof said transformers and the electromagnetic winding of said contion of said primaries, series electrical connectact-making voltmeter and an impedance in parallel with each secondary.

2. Means for resetting a contact-making voltmeter voltage regulator as claimed in claim 1, wherein said impedances comprise ohmic resistances.

mucnooams 'ronms NORRIS. NORMAN mrw'ron.

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