US2207490A - Voltage regulating relay - Google Patents

Description

.My 9, W40 E. D. T. NORRIS ET AL VOLTAGE REGULATING RELAY Filed Feb. 4, 1938 2 Sheets-Sheet l 51). 1. NM S N. ew

9, 1940- E. D. T. mamas AL,

' VOLTAGE REGULATING RELAY Filed Feb. 1938 2 Sheets-Sheet 2 Mg u 5 0 i g I iii Patented July 9, 1940- I PATENT OFFICE VOLTAGE BEGULATIN G RELAY Eric Douglas Tobias Norris and Norman Newton, Holllnwood, England, assignors to Fer-rant! Electric Inc., New York, N. Y.

Application February 4, 1938, Serial No. 188,808 In Great Britain February 12, 1937 1 Claim.

This invention relates to voltage regulating relays as used especially though not exclusively in transmission and distribution circuits, and also in individual load circuits for the control of variation of the voltage applied either to a succeeding portion of the circuit or to the load.

In certain cases it is desirable to maintain the voltage on the output side of the voltage regulator within specified limits under all load conditions in spite of voltage variations on the input side; in other cases itis 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 relay 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 fluctuations falls far short of the ideal.

It is the purpose of the present invention to provide means for greatly decreasing the time occupied in voltage regulating so as to approach more nearly to the ideal instantaneous control.

The invention may be applied to those types of voltage regulators in which a contact-making voltmeter is associated with operating mechanism, 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 Patent 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 of operation to become so high that the operating mechanism corrects the voltage in a shorter time than that taken by the contact-making voltmeter to reset and there is then alikelihood 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- 5 making voltmeter will then operate again but in the reverse direction; the cycle will thus be repeated and the regulator will hunt continually.

In practice, however, it is found that when means are adopted to reset the contact-making to 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 desiriii able to associate means with the contact-making voltmeter either for preventing or for rendering innocuous such an over-run of the contactmalring voltmeter.

The object of the present invention is to pro- 20 vide an automatic voltage regulator with means for either preventing the contact-making voltmeter from over-running when resetting or for rendering innocuous the effect of suchover-run.

The present invention in brief consists in an 25 automatic voltage regulator for adjusting voltage to a desired value, comprising current operated mechanism having a pair of coils for actuating voltage adjusting means, a reversible motor, operative mechanical connections between said motor and said mechanism, a source of electrical energy for said motor, electrical connections between said source and said motor comprising only one energising circuit, an electromagnetic contact-making voltmeter capable of resetting at a 35 speed which is sufilciently high for it to be liable to overrun in consequence of the mechanical force exerted thereon during the resetting for controlling-said energising circuit for the actuation of said motor in a direction governed by 4,9 the required change of voltage and contact-making voltmeter-overrun enact-prevention means comprising a first and second contactor in series with said coils respectively.

Referring to the accompanying diagrammatic 45 drawings- Figure 1 illustrates one convenient arrangement embodying the present invention in one form. Em

Figure 2 illustrates a modified detail of Figure 1.

Figure 3 illustrates a modified form of device for preventing over-run and/or for quick resetting.

Figure 4 illustrates a form of device for renderw ing innocuous over-run oi the contact-making voltmeter of Figure 1. I

The invention will now be described as applied in one form by way oi example to a voltage regulator embodying an astatic contact-making voltmeter, comprising 'an enclosed type mercury switch a embodying a centre connection Joined to terminal b and two side contacts 0, d. The switch is carried on a bell-crank lever e pivoted at f and actuated by the pull on the plunger 9 by an electromagnet coil 0. The electromagnet is of known form such that the pull on the plunger by the electromagnet is-substantiallyindependent of the displacement of the plunger throughout its working range. tion motor h embodies two windings i and 1 so arranged in conjunction with a condenser-2 that When the other winding is energised the motor reverses and moves the short-circuited coil in the opposite direction.

Two additional coils k, m are provided, the

former coil being in series with switch contact c,

"coil 1 and a terminal n, and the latter coil being in series with the contact d. coil 1 and the terminal.

The coils k, m are disposed in juxtaposition" n. to the operating coil 0 on the relay electromagnet;

the direction of the windings of the coils 'k, m a

and currents through them being such that when those relay contacts which are adapted to lower the output voltage, viz., contacts d, p are closed,

the coil m decreases the pull on the plunger 9 .0: having a winding which is connected in parallel with the coil 7' of the motor h.

The terminals 12, b are connected to current source.

In operation, when the line voltage decreases,

an A. C.

a the magnetic force on the relay plunger 9 is reduced, causing the plunger to i-alL- This closes the switch contacts 0, p which by energising the motor coil 1' starts the motor is in such a direction asto raise the output voltage. When the contacts 0, p close, however, a current passes through the additional coil is in such a direction as to augment the pull of the operating coil 0 on the plunger; this increase in the pull may be arranged to have any desired value. The relay is thus caused to reset in a time which is made slightly shorter than that required for the correction of the voltage to the normal value. The over-run of the motor h after opening of the contacts 0, p will, however, due to the high speed of operation, accomplish the remainder of the voltage correction, or at least will bring the output voltage within a range equal to the sensitivity of the relay.

The additional coils k, m being connected in series with the switch contacts, only operate when the motor h is excited. As soon, therefore, as the relay has reset sufliciently to open the motor circuit, the additional coil which has been in operation is no longer energised, the resetting i'orce disappears, and the relay is ready to nper- A. reversible e1ectric-induc-- ate again under its normal condition.

When the relay is in the neutral position shown in Figure 1, the catch plate r rests on a support 1 clear of the relay arm q and therefore it has no effect upon the operation of the relay. As soonas the relay has operated to cause bridging otthe' contacts :1. 01, thus starting the motor, the auxiliary et a: becomes energised and consequently raises the armature 12 together with the catch plate r. The subsequently operative resetting force on the relay causes the switch a to move towards the neutral position, but in doing so the relay arm engages the notch s in the catch plate r and the switch is prevented from running past the neutral position by the engagement of the relay arm 11 with the tongueu of the catch plate. .The armature and catch plate are associated with a damping device 2 in order that they may be retainedin the raised position for a short interval of time ai'ter' the switch has moved approximately into the neutral position. when the auxiliary electromagnet :r releases the armature v and catch plate 1', the relay is ready for iurther operation, the commencement of which is unaffected by the presence of the auxiliary electromagnet :r anditsco-bp'erating parts.

-- I Whenth e' rel y operates to bridge contacts c,

p, the elebtromagnet z la'again energised since condenser 2. The action is simil'arduring resetting or the relay to that described above, the

arm q now, however, entering the notch t.

On accountof the condenser 2 the electromagnet at is energised when either the contacts 0 and p or d and p are closed but the direction of rotation of the rotor of the motor It depends upon whether one or other of these pairs of contacts are closed.

Ina modified arrangement of Figure 1, the winding of the electromagnet :c is connected in series with the two actuating coils i, j of the motor h as shown in Figure 2, the operation being similar to that already described.

' In an alternative arrangement illustrated in Figure 3 for preventing the relay from over-running the neutral position when resetting, a tongue 9 of magnetic material is attached rigidly to the bell-crank lever e of the relay mechanism. An auxiliary electromagnet I0 is disposed with one of its pole-pieces on one side of the tongue and its other pole-piece on the other side oi. the tongue. The axial disposition of the parts is such that when therelay is in the neutral position the tongue lies between the poles of the auxiliary electromagnet and when the relay operates, the tongue moves from between the poles. The winding of. the electromagnet I0 is connected in parallel with an actuating coil of the motor h.

It will be seen therefore that the electromagnet i0 is normally unenergised so that operation of the relay from the neutral position is unail'ected. when one set of contacts oi the relay has closed, however, the auxiliary electromagnet III is energised and by its attractive force on the tongue of magnetic material, prevents the relay from over-running the neutral position.

The winding of the electromagnet l0 0! Figure 3 may if desired be connected in series with actuating coils oi the motor.

The tongue 9 of Figure 3 may be of suflicient width to enable the auxiliary electromagnet Iii to provide the resetting force for the relay by exerting a pull on the tongue when the relay 75 movement is in either of its contact making positions.

In a further modification illustrated in Figure 4, the relay is restored rapidly to its neutral 5 position, and no attempt is made to prevent overrunning of the neutral position, but a device is incorporated to prevent hunting due to the overrun. In this embodiment two contactors are used, the winding l6 oi the first contactor being connected in series with the winding 1' of the motor which latter winding causes rotation to occur in the "raise direction, while the winding ll of the second contactor is connected in series with the winding 7 oI-the motor which latter winding causes rotation to occur in the lower direction. A switch i8 operated by the first contactor is connected in series with the contacts 0, p of the relay switch mechanism and with winding l1, and a switch l9 operated by the second contactor is connected in series with the contacts p, d of the relay switch mechanism and with winding IS. A time lag device (not shown) is fitted to each contactor to delay the resetting of the contactors.

25 when the relay operates for example in the raise direction, by bridging contacts c, p the contactor winding I1 is energised, thus opening the switch is and it is thus impossible for the motor to be energised in the "lower direction 80 even though the relay over-runs the neutral position sufliciently to close the lower contacts p, d when resetting. Although the contactors op- .erate extremely quickly when energised, there is a delay inresetting alter the de-energisation of the contactors due to the time lag devices. The time lag on the contactors is such that the relay switch mechanism e is allowed to return to the neutral position before the contactor that has been opened resets.

Although a number of arrangements have been described herein, it will be evident that many other arrangements are possible without exceedng the scope of the invention.

We claim as our invention: 7

An automatic voltage regulator for adjusting voltage to a. desired value, comprising current operated mechanism having a pair of coils for actuating voltage adjusting means, a reversible motor, operative mechanical connections between said motor and said mechanism, a source of electrical energy for said motor, electrical connections between said source and said motor comprising only one energising circuit, an electromagnetic contact-making voltmeter capable of resetting at a speed which is sufliciently high for it to be liable to overrun in consequence of the mechanical force exerted thereon during the resetting for controlling said energising circuit for the actuation of saidmotor in a direction governed by the required change of voltage and contact-making voltmeter-overrun efl'ect-prevention means comprising a first and second contactor in series with said coils respectively.

ERIC nouems roams NORRIS. NORMAN NEWTON.

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