US3363354A - Method of and means for operating dc impulse transformers - Google Patents

Description

Jan. 16, 1968 D. E. RIEMER 3,363,354

METHOD OF AND MEANS FOR OPERATING DC IMPULSE TRANSFORMERS Filed Nov. 23, 1964 .J-IGZB' TIME INVENTOR.

DIETRICH E. RIE MER ATTORNEY United States a Patent 3,363,354 METHOD OF AND MEANS FOR OPERATING DC IMPULSE TRANSFORMERS Dietrich E. Riemer, Sarasota, Fla., assignor to Smith Research and Development Company, Inc., Lewes, Del., a corporation of Delaware Continuation-impart of application Ser. No. 110,080, May 15, 1961. This application Nov. 23, 1964, Ser. No. 413,266

2 Claims. (CI. 43-45) ABSTRACT OF THE DISCLOSURE An improved electro-fishing apparatus wherein the primary of an electro-fishing pulse transformer is serially connected into the charging and discharging circuits of an electro-fishing impulse condenser so that the charging and discharging currents of the condenser pass in opposite directions through the transformer.

CROSS REFERENCE TO A RELATED APPLICATION This is a continuation-in-part of my application S.N. 110,080 filed May 15, 1961, and now abandoned.

BACKGROUND OF INVENTION Field of the invention The present invention relates to a method of and means for improving the operating capacity of D.C. (direct current) impulse transformers of the type designed for electro-influencing purposes, such as electro-fishing.

Description of the prior art Direct current impulse transformers designed for electro-influencing purposes, such as electro-fishing, are quite similar to impulse transformers used in radar equipment. In such impulse transformers, the distortionless transformation of a D.C. pulse requires the L/R (inductance-over-resistance) time constant opposing the rapid buildup of a disturbing magnetic field in the transformer iron core to be large and the corresponding L/R time constant opposing the rapid rise of secondary current to be small. The main inductivity should be so large that the magnetizing current is less than li the primary current while the leakage inductivity should be so small that the secondary pulse has the same shape as the primary pulse. (See Fischers 1958 Leipzig edition of Radartechnik; also Reuben Lees Electronic Transformers and Circuits published by John Wiley & Sons in 1947.) In this connection, it may be noted that radar impulse transformers are smaller than my impulse transformers be cause radar transformers are designed for micro-second impulses whereas my transformers are designed for millisecond impulses.

In a suitably constructed D.C. electro-fishing impulse transformer, each electro-fishing impulse fed to the primary winding, induces, in the iron core of the impulse transformer, a disturbing magnetic flux having a density which first rises to a maximum value and then falls to a residual value. The rapid rise of this disturbing magnetic flux density is prevented when the main inductivity is large enough to produce a large L/R time constant. When the density (of the disturbing magnetic field) rises slowly, the fast electrical impulse responsible for'it is gone before the disturbing field has had the time it requires to grow to substantial proportions and the energy it requires to support such growth.

When the disturbing magnetic field and the leakage inductivity are both small, the primary and secondary pulses will be substantially identical in shape. In other words, when an appropriate D.C. pulse is fed to the primary winding of the transformer, a secondary D.C. pulse of substantially the same shape will be created in the secondary winding. If the primary pulse has a peak voltage of 3,000 volts and a peak current of 1,000 amps and if the transformer has a step-down ratio of 4 to 1, then the secondary pulse will have a peak voltage of 750 volts and a peak current of 4,000 amps.

The shape of each impulse, to be fed to a D.C. impulse transformer for fishing purposes, normally is an e function having a half value time of 0.3 milli-second, this being the regular shape of a pulse created by discharging a condenser through an ohmic resistor. However, any D.C. impulse of the electro-fishing type may be used with D.C. impulse transformers which are made in accordance with the present invention.

An improved circuit means has heretofore been disclosed for operating impulse transformers which, without changing their structure, size or weight, enables them to operate at substantially higher power capacities involving substantially larger values of both current and voltage. This improvement also operates inherently to effect a substantial reduction in anode corrosion and and cathode calcification. The specific arrangement disclosed is designed for operation from an AC. power source. The frequency of its spaced impulses depends somewhat upon (and has a definite relationship to) th frequency of the AC. source.

SUMMARY OF THE INVENTION Objects of the invention The principal object of this invention is to provide a simpler, more compact and otherwise superior arrangement, which enables impulse transformers to be operated at substantially higher power capacities.

Another important object is to provide a specific type of arrangement which is capable of operating at any spaced impulse frequency over a substantial range of variable power out-put.

Statement of the invention All of the objects of the present invention are attained by providing an impulse capacitor with charging and discharging circuits having a common circuit section and by connecting one winding of the impulse transformer serial'ly in that circuit section so that the charging and discharging currents pass in opposite directions therethrough. An arrangement of this character enables the impulse transformer to be operated at a capacity up to sixteen times higher than would conventionally be the case. Yet it is a simple and compact arrangement regardless of the AC. or D.C. nature of its source of power. Where AC. is used as a source of power, its operating impulse frequency may have a definite relationship to the AC. power supply frequency. With a sustained D.C. power source, its operating frequency is not dependent on a power source frequency and may be varied at will over a wide range.

BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated in the accompanying drawing wherein:

FIG. 1 is a circuit diagram of one embodiment of this invention;

FIG. 2 illustrates the relationship of the FIG. 1 impulse and reverse currents to each other and to the alternations of the alternating current (A.C.) source;

FIG. 3 is a circuit diagram of a second embodiment of the invention; and

' FIG. 4 illustrates the relationship of the FIG. 3 transformer circuit impulses to each other.

FIRST EMBODIMENT The embodiment illustrated in FIGS. 1 and 2, which is intended for electro-fishing use, conventionally includes: an impulse capacitor 1; a charging circuit therefor including an A.C. transformer 3 connected through rectifier 4 to feed a direct current impulse 5 (see FIG. 2) in one direction to the capacitor 1 during every first alternation 6 of each cycle of the A.C. power supply; an impulse transformer 8 having a primary 9 and a secondary 10 connected to electro- fishing electrodes 11 and 12 which are assumed to be submerged in the electro-fishing waters; a capacitor discharging circuit having a normally open switch 14, in the form of an ignitron 14, and being operative, when switch 14 is closed, to discharge a highvoltage low-current impulse of the electro-fishing type through the primary 9 of the impulse transformer 8 and thereby cause a low-voltage high-current electro-fishing impulse 15 (see FIG. 2) to be fired through the electrofishing waters between the electrodes 11 and 12; and means for closing the normally open switch 14 once during every second alternation 16 of each cycle of the A.C. power source 3, said switch closing means including a thyratron 17 connected to render the ignitron 14 conductive during every second alternation 16 of each current cycle of the A.C. power supply 3.

Except for the location of the impulse transformer 8, an arrangement of this character has heretofore been disclosed. This arrangement teaches: that the operating capacity of the impulse transformer 8 can be increased up to sixteen times by flowing a reverse current through the impulse transformer primary either to prevent the development (by the electro-fishing impulse) of a disturbing magnetic field in the transformer core or to remove the residual magnetism of that field and preferably reverse the magnetic polarity of the core before the next electrofishing impulse is fired. The foregoing arrangement substantially eliminates anode-corrosion and cathode-calcification because the corrosion which occurs when one electrode functions as an anode for one current is corrected when the same electrode functions as a cathode for the reverse current while the calcification which occurs when one electrode functions as a cathode for one current is corrected when that same electrode functions as an anode for the reverse current. The present invention utilizes a reverse current to achieve the same gain in power handling capacity but creates the reverse current by simpler means.

In accordance with the present invention, the impulse transformer 8 is arranged with its primary 9 connected not only in the discharging circuit for the impulse capacitor 1 but also in the charging circuit for that capacitor. With this simple arrangement, a reverse current impulse 5 will be fed in one direction through the primary 9 of the impulse transformer 8 once during every first alternation 6 of each cycle of the A.C. power source 3 while an electro-fishing impulse 15 will be fed in the opposite direction through that primary once during every second alternation 16 of each cycle of the A.C. power source. In other words, the charging current for the capacitor 1 is used to counteract the disturbing magnetic field efiect produced by the electro-fishing impulse discharged by the capacitor 1.

If the peak current of the electro-fishing impulse 15 ranges, for example, from 2,000 to 4,000 amps, the peak value of the reverse current 5 may range from 50 to 100 amps, more or less. While the high and low peak impulses 15 and 5 are both transmitted by the transformer 8 to the fishing electrodes 11 and 12, only the high peak impulses 15 are strong enough to orient the fish during a fishing operation. The low peak impulses 5 should be weak enough to avoid any noticeable orienting effect upon the fish.

The first embodiment is tied to the alternations of the A.C. source. It is useful in operating at a spaced impulse frequency which is related to the frequency of the A.C. source. For example, with a 60 cycle source it may operate at say 60 electro-fishing impulses per second or at some other lower value related to 60 cycles such as 30 electro-fishing impulses per second.

SECOND EMBODIMENT The second embodiment illustrated in FIGS. 3 and 4 is essentially the same as the first embodiment in that it places the primary of the impulse transformer 8 serially within the charging and and discharging circuits of the capacitor 1. It differs from the first embodiment in that: (a) in the charging circuit, it uses a direct current generator 23 and choke 24 in place of the AC source 3 and rectifier 4 of the first embodiment; and (b) in the discharging circuit, it uses the voltage-doubling, switch-reversing arrangement of KreutzerUS. Patent No. 2,836,735 (involving voltage-doubling capacitor 25 and alternately operating pairs of switches 26, 26 and 27, 27) in place of switch 14 of the first embodiment.

We assume that the capacitors 1 and 25 of the second embodiment are relatively large and small in relation to each other say 30,000 and 500 microfarads respectively. With this assumption, it will be appreciated that the charging current for the large capacitor 1 is used to counteract the disturbing magnetic field produced by the electrofishing impulse 30.

In operation, the large impulse capacitor 1 is charged (and maintained in substantially a fully charged state) by the direct current generator 23. In order to fire a DC electro-fishing or high-peak impulse 30 (see FIG. 4) through the impulse transformer primary 9, the smaller capacitor 25 is connected in series with the larger capacitor by one pair of ignitrons, say, 26. This causes both capacitors to discharge in the same direction until the small capacitor is exhausted. Thereafter the large capacitor continues to discharge in the same direction until it has fully charged the small capacitor in the opposite direction. When the voltages on both capacitors 1 and 25 are equal and opposite, current stops flowing in the dis charge circuit and the ignitrons 26 become non-conductive.

The next succeeding high-peak impulse 30 is fired by closing the other pair of ignitrons 27 to connect the small and large capacitors once again in series but with the terminals of the small capacitor 25 reversed so that its voltage no longer opposes the voltage of the large capacitor. Once again the large capacitor discharges in the same direction until the small capacitor is first fully discharged and then fully recharged to a polarity opposing the charge on the larger capacitor 20. This cycle of connection closures is repeated for each successive pair of high peak electro-fishing impulses 30, which are fired by the apparatus.

During the firing of each high peak impulse 30 over the discharging-charging period of the small capacitor 25, the charge on the large capacitor 1 is only reduced to a slight degree due to the great difference in capacity between the two capacitors. When the flow of a given highpeak impulse through the transformer primary ceases, the direct current generator 23 immediately creates a reversely flowing low-peak current 31 (see FIG. 4) and maintains it over the longer 3 or 4 milli-second period required to restore the large capacitor 1 to a fully charged state. The inductive choke 24 aids in keeping the peak magnitude of the charging impulse 31 low and in reducing the peak current load on the generator 23.

The impulses of the second embodiment shown in FIG. 3 are not tied to the alternations of an AC current; hence, the second embodiment is useful in providing a wide range of spaced impulse frequencies, ranging, say, from 1 to impulses per second. With, say 100. (0.3 millisecond) electro-fishing impulses per second, there willbe one reverse current impulse during the 9.7 milli-second and the beginning of the next successive electro-fishing impulse. With a generator 23 of given voltage and current capacity, the strength and duration of each reverse current impulse depends primarily on the inductance 24. With this limitation in mind, it will be understood that the strength of each reverse current impulse 3-1 should be such that the corresponding impulse induced in the secondary of the transformer does not noticeably affect the fish.

It will also be understood that the stronger reverse current impulses require less time to charge the condenser 1 than do the weaker impulses. However, the power remains the same; hence, the duration of each reverse current impulse 31 necessarily will be long enough to produce an iron core magnetizing effect of effective counter magnetizing value.

It should be understood: that each, of the two arrangements which I have disclosed, is primarily designed to work with one constant power output; and that the pulse transformer operates under optimum conditions when the arrangement, in which it is used, is working with the one constant power output for which it was primarily desi ned. With that understanding, it will be further understood that, if the said one power output of that arrangement is thereafter changed, as by changing the peak voltage or pulse rate of the impulses, the pulse transformer will continue to work but not under optimum conditions unless the strength and duration of the reverse current is changed to provide new optimum rate of compensation.

By DC impulse current of the electro-fishing type, I mean a direct current of the spaced impulse type disclosed (or usable in electro-fishing apparatus or operations of the character disclosed) in prior US. patents on electrofishing subjects matter. Among there are: #2,764,832 dated Oct. 2, 1956; #2,792,659 dated May 21, 1957; #2,836,735 dated May 27, 1958; #2,850,832 dated Sept. 9, 1958; and #2,850, 833 dated Sept. 9, 1958.

By calcification, I mean the deposit which builds up on the cathode as a result of the flow of electro-fishing impulses. A calcification deposit, which resulted from the flow of electro-fishing impulses through sea water and which, when scraped from a copper cathode, had the appearance of a gray powder, analyzed as follows:

Zinc, iron and aluminum plus traces of lead;

assumed to aggregate, about 1.6

The metals were present primarily as oxide-hydrates or as carbonates. It is probable that they were originally present entirely as hydroxides and that the carbonates were formed subsequently by reaction with the carbon dioxide of the air.

The magnitudes, of the peak voltage and length of the electro-fishing and counterflowing impulses, used in the secondary circuit, may be varied over a wide range depending upon various factors. Thus, the electro-fishing impulse will vary depending upon such factors as the type of operation, i.e. trawl-fishing, purse-seine pumping, etc., the size and species of the fish, the desired reach of the electrical field surrounding the anode, the desired dimensions of the taxis section of that field, etc. The magnitude variations in the counterflowing impulse will largely depend upon the magnitudes selected for the electro-fishing impulse. However, in each case, the magnitudes required to effect a desired result may be readily determined by the operators skilled in the art because such operators will know, or may readily determine by simple and routine experiment, what magnitudes are required to perform a given function.

Obviously, the peak voltage and length magnitudes of the core-magnetizing and core-demagnetizing impulses used in the primary circuit will vary largely depending upon the magnitudes used in the secondary circuit. They may also vary for other reasons including the location of the impulse transformer in relation to the operation being conducted. For example, in a purse-seine pumping operation, the impulse transformer may be located on a ship within less than feet from the most distant electrode whereas, in a trawling operation, it may be submerged with the trawl gear and thus located at a distance of /2 mile or more from the ship. Furthermore, in some instances, it will be desirable to use step-up impulse transformers while, in other instances, step-down transformers may be employed; hence, said magnitudes will vary accordingly.

The pulses 5 and 15 are equal energy pulses as are the pulses 30 and 31. The discharge time or length of pulses 15 and 30 may be much more than but normally will not be less than 0.3 milli-second. The charge time or length of pulses 5 and 31 normally will be many times that of pulses 15 and 30 respectively.

Having described my invention, I claim:

1. An electro-fishing apparatus for electrifying fishing waters by flowing an electrical current through the waters between submerged electro-fishing electrodes, comprising:

(A) a DC impulse transformer of the electro-fishing type having a magnetizable core and inductively connected primary and secondary windings;

(B) primary circuit means serially connecting a pulse capacitor with said transformer primary'so as to charge and discharge said capacitor with impulses fired through said transformer primary, including (1) discharge circuit means for discharging said capacitor at spaced intervals to provide coremagnetizing DC impulses, of the short-duration, high-voltage, electro-fishing type, and for flowing said impulses in one direction through said primary winding, and

(2) charge circuit means for charging said capacitor at alternate intervals to provide core-demagnetizing DC impulses, of relatively longer duration and lower voltage than said coremagnetizing impulses, and for counter-flowing said core-demagnetizing impulses in the opposite direction through said primary winding; and

(C) secondary circuit means serially connecting said transformer secondary with said submerged electrodes so as to energize said electrodes (1) at said spaced intervals with anode-corroding,

cathode-calcifying, fish-orienting DC electrofishing impulses corresponding to said coremagnetizing impulses, and

(2) at said alternate intervals with counter-flowing DC impulses (a) corresponding to said core-demagnetizing impulses and (b) having a peak voltage insuflicient to reorient the fish and a duration long enough to effect a substantial repair of the anode-corrosion and cathode-calcification caused by said electro-fishing impulses.

2. An electro-fishing method for electrifying fishing waters by flowing an electrical current from the secondary of an impulse transformer through the waters between submerged electro-fishing electrodes, comprising:

(A) discharging a pulse capacitor at spaced intervals in one direction through the primary winding of said impulse transformer to provide (1) said primary with core-magnetizing DC impulses of the short duration, high-voltage, electro-fishing type, and

(2) said secondary with an electrode-energizing,

anode-corroding, cathode-calcifying, fish-orienting DC electro-fishing impulses corresponding to said core-magnetizing impulses; and

(B) charging said pulse capacitor at alternate intervals in the opposite direction through said primary winding to provide (1) said primary with core-demagnetizing DC impulses of relatively longer duration and lower voltage than said core-magnetizing impulses, and

(2) said secondary with counterflowing electrodeenergizing DC impulses having a peak voltage insufiicient to reorient the fish and a duration anode corrosion and cathode-calcification caused by said electro-fishing impulses.

References Cited UNITED STATES PATENTS Wolfirarnm et al. 328--67 X SAMUEL KOREN, Primary Examiner.

long enough to effect a substantial repair of the 15 WARNER H. CAMP, Examiner.

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