US2777098A - Magnetically controlled electric counting apparatus - Google Patents

Description

,1957. P. DUFFING ETAL MAGNETICALLY CONTROLLED ELECTRIC COUNTING APPARATUS 2 Sheets-Sheet 1 Filed May 16, 1952 1957- P. DUFFING ETAL 2,777,098

MAGNETICALLY CONTROLLED ELECTRIC COUNTING APPARATUS Filed May 16, 1952 2 Sheets-Sheet 2 United States Patent O MAGNET-ICALLY CONTROLLED ELECTRIC COUNTING APPARATUS Paul Dutfing, Berlin-Siemensstadt, and Gerhard Conradi,

Berlin-Tegel, Germany, assignors to Siemens-Schuckertwerk Aktiengesellschaft, Berlin-Siemensstatlt, Germany, a corporation of Germany Application May 16, 1952, Serial No. 288,346

Claims priority, application Germany July 27, 1951 9 Claims. (Cl. 317-148) Our invention relates to magnetically controlled electric counting apparatus and is hereinafter described with reference to the drawings, in which:

Fig. l is a circuit diagram for a counting apparatus of the type here concerned, and Figs. 2, 3 and 4 are explanatory coordinate diagrams relating to the operation of such an apparatus;

Fig. 6 is a schematic circuit diagram of an example of apparatus according to our invention, While Figs.

and 7 are pertaining explanatory coordinate diagrams;

Fig. 8 is a schematic circuit diagram of a welding control apparatus according to the invention; v

Fig. 9 shows a detail of the apparatus according to Fig. 8; and

Fig. 10 is a schematic circuit diagram of a voltage regulator according to the invention.

Magnetic counting circuits as previously proposed, have an iron-cored choke coil (counting reactor) of an approximately rectangular magnetic characteristic whose winding is connected to the secondary 'of a saturable transformer also of an approximatelyrectangular magnetic characteristic. The primary of the transformer is traversed by alternating current supplied from an alternating-voltage source, for instance, through a resistor. As long as the transformer is saturated, the voltage across its primary is virtually zero. However, when the transformer is being reversely magnetized a voltage :ap-

pears across its primary winding due to the fact that the transformer reactance increases when the transformer core is desaturated. The time integral of the voltage required for the remagnetization is proportional to the product of'the number of windingturns times the saturating magnetic flux, this product being practically constant and independent of the rate of current change. The voltage integral also occurs in the secondary of the transformer and tends to reverse the magnetization of the counting reactor. When the voltage integral of the counting reactor is larger than the voltage integral supplied from the saturable transformer, a certain number of voltage integrals must accumulate before the counting reactor reaches saturation, and only the next following voltage integral can release a large current pulse in the electric circuit of the counting reactor. All preceding voltage integrals produce only small current pulses corresponding in magnitude to the magnetizing current of the counting reactor.

When referring in this specification to the magnetizing current, we understand this term to mean the magnetiz ing current obtaining when the reactor operates on its ascending or descending branch of its hysteresis loop. Consequently, with an ideal, accurately rectangular hysteresis loop, the magnetizing current is proportional to the coercive force of the reactor core material.

If the turn number of the reactance winding in the counter reactor is made variable, the number of the occurring voltage pulses which must accumulate before an appreciable current pulse is issued can be adjusted by selectively changing the number of winding turns.

schematically illustrated in Fig. 1.

'6 start acting upon the counting reactor.

Patented Jan. 8, 1957 re 1C6 2 The electric circuit of such a counting reactor is i The core 101? the counting reactor consists of a high-grade iron or thelike magnetizablev material which has an approximately rectangular magnetization characteristic. Disposed on the core is the reactance winding 2 of the reactor. This winding is connected through a rectifier 3 to the secondary winding 6 of a saturable transformer 4 whose primary 5 is energized from a source of alternating voltage, for instance, through an ohmic series resistor 7. Series connected with the reactor winding 2 is the make contact 10 of a push button switch 9 and also the winding 12 of a relay, circuit-breaker release or the like -'device Which responds to a given minimum magnitudeof The core of the counting reactor is also through a rectifier 14and a resistor 15 to thealternatingcurrent source under control by a break contact 11 of the push button switch 9.

The diagram of Fig. '2 serves to elucidate the relation of the induction B (abscissa) to the field strength H '(ordina'te) of such a counting reactor. When the break contact 11 is closed, a large negative current flows through the winding 13 of the counting reactor and places this reactor into saturated condition. Hence, before'the switch '9 is depressed the counting reactor is in a magnetic condition corresponding to the point a in Fig. 2. When switch 9 is actuated and closes its make contact 10 the periodic voltage pulses issuing from the secondary Assume, for instance, that the first 'pos'itive voltage pulse places the reactor into a magnetic condition corresponding to point b1.

After this pulse ceases the reactor condition reaches the .point a1. The next positive voltage pulse .magnetizes the counting reactor from-point a1 up'to point b2. After cessation of the pulse the reactor magnetization corresponds to point a2. The third voltage pulse raises the magnetization of the reactor into the range of saturation.

Hence the eifective reactance drops, and a large current pulse is released. The current pulses flowing through'the control winding 12 forms part.

If a larger number of voltage pulses are to be suppressed, the turns number of the winding 2 on the counting reactor must be correspondingly enlarged. This reduces the magnetizingcurrent so that the current pulses occur in the manner typified by the current-time diagram of Fig. 4. As exemplified the first five current pulses have a small amplitude corresponding to the magnesizing current of the counting reactor. sixth voltage pulse places the reactor into the saturated range and releases a correspondingly large current pulse in the circuit to be controlled.

The number of the reactor winding turns therefore may be so chosen that it determines the desired number I While the Y therefore, have not been suitable for accumulating, for instance, as many as 12 or more voltage pulses before a large pulse of control current is released.

It is an object of our invention to overcome these difficulties and to provide magnetic counting apparatus generally of the above-mentioned type that are capable of suppressing a larger number of voltage pulses than heretofore applicable.

To this end, and in accordance with a feature our invention, an ohmic resistor is parallel connected to the valve or rectifier in the circuit of the counting reactor. In the counting apparatus according to Fig. 1 such a resistor is to be shunt connected to the rectifier 3. Since the rectifier 3, as assumed above, permits the positive voltage pulses to become effective for the remagnetization of the reactor, the parallel connected resistor also permits the negative voltage integrals to again magnetize the reactor back toward the original condition. It may therefore seem that the provision of such a resistor is contradictory to the intended performance. However, the negative voltage integral does not act in its full magnitude but is diminished by the voltage integral fi-r'dt, in which i is the current flowing through the shunt resistor and r the resistance magnitude of that resistor. As long as the ratio of the voltage integral to the total resistance of the circuit is smaller than the magnetizing current of the reactor, nothing is changed as far as the operation of the reactor device is concerned.

- Only when, at a higher number of reactor Winding turns,

the magnetizing current becomes equal or smaller than 'the ratio of the voltage of the voltage integral to the total resistance of the circuit can a back-magnetization of the reactor occur. Since the voltage integrals are not exactly rectangular, an increased number of reactor winding turns is accompanied at first by a partial and then by a larger back-magnetization until a limit value for the back-magnetization is reached. For instance, with a high number of reactor winding turns, the backmagnetization' may take the course indicated in the diagram of Fig. 5. As shown, a positive voltage integral may produce a remagnetization of the reactor core from point an to point a2 of the magnetic characteristic. The immediately following negative voltage integral produces a reverse magnetization down to point as. The next positive voltage integrals finds the magnetization in the condition of point a It follows that the ohmic resistor permits increasing the number of the voltage integrals which can be suppressed, this being due to the fact that, from a certain turns number on, the backmagnetization occurs in a leap-frog progression, while at smaller turn numbers a back magnetization during the negative voltage interval can not yet occur.

Such a device would always count accurately if the shape of the voltage interval supplied from the saturable transformer were invariable. Fluctuations of the line voltage however causes a change in the shape of the time integral. Since the magnitude of this integral is constant, a reduction in line voltage has necessarily the effect of increasing the duration; and since the current flowing during the back-magnetization interval is limited in amplitude by the magnetizing current of the counting reactor, the integral fi-r-a't increases with a decreasing voltage. That is, the back-magnetization is smaller at smaller voltages and larger at high voltages. This has the consequence, that for instance, with a declining voltage the number of pulses that are being suppressed becomes smaller. This of course is often undesired. According to another feature of the invention, however, this deficiency is eliminated by giving the counting reactor another winding and energizing this winding in dependence upon the voltage driving the current through the primary Winding of the saturable transformer.

The above mentioned features of the invention are embodied in the counting apparatus shown in Fig. 6.

Since this apparatus is partly similar to that of Fig. 1, the same reference characters are applied to similar respective elements. In contrast to the apparatus according to Fig. 1, an ohmic resistor 20 is connected across the rectifier 3.. Besides, the counting reactor 1 is equipped with an additional winding 21 which is energized through a smoothing reactor 27 from a rectifier device 22 connected to the line-voltage supply terminals through an ohmic resistor 23.

The magnetic characteristic and operation of such an apparatus are apparent from Fig. 7. The current through winding 21 of reactor 1 produces a premagnetization represented in Fig. 7 by the distance of the vertical broken line p from the ordinate axis. The remagnetization due to a positive voltage integral may now occur from a starting point a1 to a point a2, while the next following negative voltage integral produces a backmagnetization from point as back to point as. In comparison with the back-magnetization according to Fig. 5, the magnetizing current has become larger due to the effect of the premagnetizing reactor winding 21.

If now the line voltage becomes smaller, for instance, the broken-line vertical p shifts accordingly to the left. This has practically no eifect upon the remagnetization caused by the positive voltage integrals. However, during back-magnetization by negative voltage integrals the current in the resistor is now smaller than previously. Hence, by a suitable dimensioning of the current through winding 21, it can now be made certain that the current becomes'smaller in proportion to the increase in pulse duration, thus maintaining the back-magnetization always at the same value. If premagnetization occurring at normal line voltage is chosen somewhat differently, only a partial compensation is obtained.

In some cases it may also be desirable to have the number of suppressed voltage pulses become smaller with an increase in voltage. Then the premagnetization is so chosen that the vertical p lies at the left of the ordinate axis and toward the right with a decreasing voltage.

In the illustration of the welding controller shown in Fig. 8, the elements corresponding to those of Figs. 1 and 6 are denoted by the same respective reference numerals. The welding controller has an electromagnetic switch 24 with a make control coil 25 and a break control coil 26. The movable contact of the switch is closed when the make control coil 25 receives a current pulse of a given minimum magnitude. The switch remains magnetically closed after the cessation of the pulse and is thereafter opened only when a current pulse of a given magnitude is passed through the break control coil 26. Then the switch remains open even after termination of the opening pulse. The break control coil 26 is series connected with the main winding 2 of the counting reactor 1. The make control coil 25 is connected through the make contact 10 of push button switch 9 across a capacitor 30 which is charged from the line voltage through a high-ohmic resistor 31 and a rectifier 32. The welding electrodes are indicated at 34.

The operation of the control apparatus is as follows. When the break contact 11 of push button switch 9 is closed, the winding 13 of the counting reactor 1 is excited from the line terminals and premagnetizes the reactor so strongly that it is saturated in the negative range of its magnetic characteristic. When the push button switch 9 is depressed, the magnetic condition of the reactor corresponds to point a in Fig. 7. The closing of contact 10 causes the capacitor 30 to discharge through the make control winding 25. The discharging current pulse in winding 25 causes switch 24 to close its contact. After the discharge through winding 25 is terminated, the continuing residual current in this winding is so small that it does not interfere with the switch 24 being opened when coil 26 is subsequently excited by a current pulse of the necessary magnitude. The closing of switch 24 places the primary 5 of the saturable transformer 4 on the line voltage, and the counting reactor 1 commences to count pulses. After a given number of voltage integrals, depending upon the ettective turn number of the reactor winding 2, the reactor is remagnetized up to saturation and a current pulse of sufliciently high magnitude passes through the break control coil 26 thus opening the svn'tch 24. This terminates the welding operation, the push button switch may be released and its next actuation causes a repetition of the above described performance.

An example of a design for the above-mentioned electromagnetic switch 24 is shown in Fig. 9. The switch has an armature 40 in the field of two holding magnets 41 and 42. Each holding magnet has a permanent magnet portion 43 or 44 which may be substituted by a winding energized by direct current. Connected with the magnet portion are pole structures which carry the respective control coils 25 and 26. In addition, a magnetic shunt path 45 or 46 is provided for each permanent magnet. The armature is resiliently supported, for instance, by elastic wires 47. The make control coil 25 is connected with such a polarity that the current pulse from the capacitor (30 in Fig. 8) induces a flux in a direction opposed to the fiux direction of the permanent magnet 43. The break control coil 26 is so connected that the current flowing through the rectifier 3 produces a flux opposed to that of the permanent magnet 44. If, for instance, the armature 40 is in engagement with the holding magnet 41 and if the coil 25 is excited as described in the foregoing, the holding flux through the armature is diverted to pass through the shunt 45, and the resilient support of the armature is permitted to swing it toward the right into the field of the holding magnet 42. The holding magnet then retains the armature until the break control coil 26 is excited whereupon the armature swings back to the holding magnet 41 and is retained thereby. The movable contact member of switch 24 (not shown in Fig. 9) is connected with the armature 40 or is part thereof.

It has been assumed in the foregoing that the premagnetization produced by the reactor winding 21 is caused by a direct voltage. However, there is no objection to using an alternating voltage for this purpose. The circuit connection is then such that the desired polarity of premagnetization obtains within the interval in which the negative voltage integrals are effective.

Fig. shows another embodiment of apparatus according to the invention in which a counting reactor operates for regulating purposes. The same reference numerals as in the preceding figures are used for denoting respectively similar elements. In this apparatus the switch 24 is closed a given interval of time and thereafter is open another given interval of time. The apparatus is intended to operate in such a manner that an increase in supply voltage results in a decrease in the ratio of closing interval to opening interval. To this end, the apparatus has two counting reactors 1 and 1. Each reactor has a main winding 2 or 2 series connected with a rectifier 3 or 3' to the secondary 6 or 6' of a saturable transformer 4 or 4' whose primary 5 or 5' is connected through a series resistor 7 and a main switch 54 across terminals 55, 56 to be impressed by the voltage to be regulated. A shunt resistor or 20' is connected across the rectifier 3 or 3. The two counting reactors have respective premagnetizing windings 21 and 21 connected in series with each other to the voltage supply through a rectifier 22 and a resistor 23. Each counting reactor has an additional winding 13 or 13 connected through a resistor 14 to a source of substantially constant direct current voltage. An electromagnetic switch 24, designed as described above, has two auxiliary contacts 50 and 51 so connected with the windings 13 and 13 that in one position of the switch the winding 13 is energized by the rectified alternating voltage, while in the other position of the switch the winding 13' is thus energized. The make control coil of switch 24 is excited by the pulses .6 released by the reactor winding 2, and the break control coil 26 is excited by the pulses from reactor winding 2..

The apparatus is placed in operating condition by the closing of its main switch 54. The resistors 20 and 20' are so dimensioned that the counting reactors operate in accordance withthe above-described leap-frog principle. After a given number of voltage pulses, the make control coil 25 is supplied with a current pulse of the magnitude required for closing the switch 24. This switch is thereafter opened only when, counting from the closing .xoment, a given number of voltage integrals have sufiiciently magnetized the reactor 1'.

If the windings 21 and 21 were not provided, the period of time during which the switch is closed would increase with an increase in supply voltage, and the period of time during which the switch is open would likewise increase since, as explained, the integral f i-r-dt decreases with an increasing voltage. However, if the ratio of opening period to closing period is to become smaller with an increasing voltage and to become larger with decreasing voltage, the following means may be applied.

The reactor 1 may be given a Winding 21 which produces such an additional premagnetization that, for instance during voltage fluctuations, the closing period remains constant. Instead, the Winding 21 may be chosen so that the closing period becomes smaller with an increasing voltage. The reactor 1 may also be given a winding 21' which is so chosen that the closing period during an increase in voltage becomes even larger than without this winding. That is, in this case the premagnetization according to Fig; 7 would be so chosen that it is negative. When the closing period during voltage fluctuations is constant and the opening period is increased with an increase in voltage, or when the closing period is reduced with an increasing voltage while the opening period either remains constant or increases, then the ratio of closing period to opening period becomes smaller during increases in voltage and becomes larger during decreases in voltage. Consequently, if the switch 24 is connected in an electric circuit energized by constant voltage, the average value of the current in this circuit decreases with an increasing voltage. Such an apparatus may be advantageously used in the excitation circuit of an alternating-current synchronous machine whose alternating voltage energizes the saturable transformer. The apparatus then operates as a regulator which maintains the alternating voltage at a constant value, the operation being similar to that of a Tirrill regulator.

It is also possible to secure a regulating performance by connecting into the circuit controlled by switch 24 the coil of a regulator which is energized by the current through the switch and produces the desired regulating operation in dependence upon the chosen ratio of closing period to opening period.

It will be understood from the foregoing that after each counting operation the counting reactor 1 or 1" is reset to the range of negative saturation of its magnetic characteristic due to the saturating flux of winding 13 or 13. Consequently, at the beginning of the counting operation the counting reactor is always at point a of the characteristic. During the period within which the counting reactor is magnetized on the negative saturated branch of its characteristic, the negative voltage pulses are effective through the resistor 20 or 20' thus producing large current pulses. These current pulses, however, have no efiect upon the control operation because the switch, as shown in Fig. 9, is polarized so that these pulses merely augment the holding flux but do not initiate a change in switch position.

It will be obvious to those skilled in the art upon a study of this disclosure that magnetic counting apparatus according to our invention may be modified in various respects and may be embodied in apparatus other than specifically illustrated and described, without departing from the essence of our invention and within the scope of the claims annexed hereto.

We claim:

1. Apparatus for counting electric impulses, comprising alternating-voltage supply means, a circuit including a current-responsive device to be controlled, a saturablecore transformer primarily connected with said supply means and secondarily connected in said circuit, a saturable counting reactor of high coercivity having a main winding and a premagnetizing winding, an electric valve series connected with said main winding in said circuit, a resistor parallel connected with said valve, and a rectifier connecting said premagnetizing winding to said supplymeans.

2. Apparatus for counting electric impulses, comprising alternating-voltage supply means, a circuit including a current-responsive device to be controlled, a saturablecore transformer primarily connecting with said supply means and secondarily connected in said circuit, a saturable counting reactor of high coercivity having a main winding and a premagnetizing winding, an electric valve series connected with said main winding in said circuit, a resistor parallel connected with said valve, a rectifier connected with said supply means to provide a direct current variable in dependence upon voltage fluctuations of said supply means, and a premagnetizing circuit connected to said rectifier and including said premagnetizing winding, said premagnetizing circuit being rated and poled for compensating the effect of said fluctuations in the operation of said reactor.

3. A magnetic counting apparatus, comprising alternating-voltage supply means, electromagnetic means to be controlled having a control coil, a saturable transformer primarily connected with said supply means for having a secondary circuit including said control coil, a saturable counting reactor having a main winding and a premagnetizing bias winding and an auxiliary saturating winding, an electric valve having a shunt resistor and being series connected with said main winding in said secondary circuit, rectifier means connecting said bias Winding with said supply means, a reset circuit connecting said saturating winding with said supply means for resetting when energized said reactor after a counting operation to a given initial state of saturation, and a control switch having a make contact and a break contact, said make contact being series connected in said secondary circuit to start when closing the reactor operation, and said break contact being series connected in said reset circuit.

4. A magnetic counting apparatus, comprising an electromagnetic switch to be controlled having a normally open contact and having a make control coil and a break control coil, alternating-voltage supply means, a saturable transformer primarily connected with said supply means through said switch contact and having a secondary circuit including said break control coil, a saturable counting reactor having a main winding and a saturating Winding, an electric valve and a resistor parallel-connected with each other and series connected with said main winding in said secondary circuit, a reset circuit connecting said saturating Winding with said supply means, said make control coil having an energizing circuit, a control switch having a make contact and a break contact, said make contact being connected in said energizing circuit, so that actuation of said control switch causes said make control coil to close said secondary circuit for starting said counting reactor to operate, and said break contact being connected in said reset circuit so that release of said control switch causes said break control coil to open said secondary circuit and causes said saturating winding to magnetically reset said counting reactor.

5. Apparatus for counting electric impulses, comprising alternating voltage supply means, an electromagnetic switch to be controlled having a make control coil and a break control coil, said two coils having respective coil circuits, each of said coil circuits comprising in combination a saturable-core transformer connected with said supply means to impress voltage pulses upon said circuit, a saturable counting reactor of high coercivity having a main winding and a premagnetizing winding, an electric valve series connected with said main winding in said coil circut, a resistor parallel connected with said valve, and a rectifier connecting said premagnetizing Winding with said supply means, whereby the closing and opening periods of said switch are controlled by said coil circuits in dependence upon the voltage of said supply means.

6. Apparatus for counting electric impulses, comprising an alternating-current supply circuit, a saturable-core transformer having a primary side connected in said supply circuit and having a secondary circuit, a circuit device to be controlled, said device being connected in said secondary circuit and responsive to occurrence of a current pulse of a given minimum amplitude, a saturable counting reactor of high coercivity and an electric valve series connected with each other in said secondary circuit, and a resistor parallel connected to said valve.

7. Apparatus for counting electric impulses, comprising alternating-voltage supply means, a saturable-core transformer connected to said supply means and having a secondary circuit, a saturable counting reactor of high coercivity having a main winding and a premagnetizing winding, a current-responsive device to be controlled, an electric valve connected in said secondary circuit in series with said main Winding and in series with said device, a resistor parallel connected with said valve, and circuit means connecting said premagnetizing winding with said supply means to provide the reactor with premagnetization variable in dependence upon the supply voltage.

8. A magnetic counting apparatus, comprising alternating-voltage supply means, a saturable transformer primarily connected to said supply means and having a secondary circuit, a current-responsive device to be controlled, a saturable counting reactor having a main Winding and an auxiliary saturating Winding, an electric valve series connected in said secondary circuit in series with said main winding and in series with said device, a resistor connected across said valve, and a controllable reset circuit connected with said auxiliary Winding for resetting said reactor after its counting operation to a given initial state of saturation.

9. Apparatus according to claim 8, comprising a control switch having a make contact and a break contact, said make contact being series connected in said secondary circuit to start when closing the reactor operation, and said break contact being series connected in said reset circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,914,220 Sorensen June 13, 1933 1,981,921 Logan Nov. 27, 1934 1,997,179 Logan Apr. 9, 1935 2,216,595 McCarty Oct. 1, 1940 2,259,647 Logan Oct. 21, 1941 2,430,457 Dimond Nov. ll, 1947 2,518,865 Cartotto Aug. 15, 1950

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