US1384734A - Electrical testing system and apparatus - Google Patents

Description

C.-A. ANDERSON.

ELECTRICAL TESTING SYSTEM 'AND APPARATUS.

APPLICATION FILED SEPT,24, I919.

Patented July 19, 1921.

PATENT crates.

onanmqcn A. annnnson, or aniannn, Kansas.

ELECTRICAL TESTING- SYSTEM APE'MATUS;

\ essence.

i I Specification of Letters yatent. Patgnted July 19, ang

Application filed September 24, 1919. Serial No. 326,605.

Zdall whom it may concern:

Be it known that I, CLAnENcr. A. ANDER- SON, a citizen of the United States, residing at Abilene, in the county of Dickinson and State of Kansas, have invented certain new and useful Improvements in Electrical Testin Systems and Apparatus, of which the to lowing is a specification, reference being had therein to-the accompanying drawing.

My invention relates to testing sets and more particularly to an arrangement and combination of circuits and apparatus for useas a troublemans or linemans portable test set. a

An object of the invention is to provide a simple and effective means for the location.

of various faults or defects in circuits such asfteleph'o'n'e and telegraph line circuits. I Another object of the invention is to pro:

.20 vide a convenient and effective arrangement for making certain tests without the necessity of disconnecting or otherwise disarranging the circuits being tested and without having to break through the insulation; A further obfectof the invention is to provide a novel form of finder or exploring coil arranged to be conveniently held. in operative relation with the conductor being tested.

Various other objects of my invention will be apparent. fro'ma perusal of the accompanying specification and drawing.

1 y invention is illustrated in the accompanying drawings, in which Figure 1 is a diagram of the circuit arra-ngement;

vFig. 2 is a side view of the exploring coil; Fig. 3 is an end view thereof showing the 40 movable clamping side open; and

Fig. 4t is a view showing the holder for the exploring coil and its cable attached to the wall of a suitable instrument box.

-'Referring to thed-rawings in particular,

'45 and first to the diagram of Fig. 1, l indicates a telephone magneto generator: of the standard or well known typehaving contacts such as 2, 3, 4 and 5 arranged to be. automatically operated-upon operation of the generator in a manner well known tothose skilled in the art, in the presentcase the'arrangement beingsuch that-upon operation of the generator the contact 2 will move out- ,wardly into engagement. with contact moving the contact 3 out of engagement with contact at and into engagement with contact 5,-so*that contacts 2, 3, and 5 remain in electrical connection during operation of the generator. In addition to these usual automatically operated contacts, I provide an additional make and break switch ele- -ment 6 operated in the operation of the generator; This switch consists of a movable contact element 7 mounted to turn in fixed relation with the shaft 8 of the magneto armature and, arranged to make contact with a brush or contact spring 9 twice during brush or contact member 13. The contact member 7 is so set or timed in relation to the cycle of the generator that it will make contact with the spring-,9 immediately after the peak of the current wave of the generator is reached, which occurs twice for every revolution of the armature. Connection is extended from the free side of generator at 12 through conductor 14:, to the line terminal post 15 of the test set. The set is provided.

' with a telephone receiver 16,- .transmitter 17,

induction coil 18, battery 19 and condenser 20, the secondary winding 21 of the induction coil and the receiver 16 being normally connected-1n series across the llne terminal posts 15 and 22,through the normally closed contacts 3-4, 23-,'24, and 25-26, by way of conductors 27,28, 29, 30, 81 and 32. The primary winding 84 of the induction coil, the transmitter 17 and battery 19 are connetted in series through a. suitable normall open controlling kev or push button 33.

resistance suitably proportioned to the resistance of the receiver, is connected ,in shunt of the receiver terminals through the normally closed contacts 2324 and the normally open generator-controlled contacts It will be noted that the normally closed contacts 25--26 which connect one terminal of the receiver to the line post 22'also norclosed contacts 2526 and 23-.24, and normally open contacts 26-36 and 24-37 constitute the contacts of a single key or push button 38 which may be of any known type capable of controlling the connections in a manner similar to that shown. The'contacts 26-36, when closed, connect the condenser 20 across the line terminal posts via conductors 30 and 31.

and 22 through the intermittent contact spring 9 by way of conductors 39 and 14. The contact 36 is also connected through conductor 40 to one terminal of a finder-or exploringcoil 41, the other terminal of which is connected through conductor 42 to contact 37 so that actuation of the key 38 to close contacts 26-36 and 24-37 connects the exploring coil in series with the receiver The conductors 40-42are preferably in the form of flexible leads. of suitable length to enable the explormanner as through a pair of flexible con-v ductors 45-46 terminating intest clips 47-48, respectively.

cuit connections may be mounted in any suit-' The entire apparatus with its various cirable manner -for convenience .in use and portage as is usual with linemen; test sets of the portable type, as by mounting in'a box or casing with the receiver leads, conductors -42 and -46 in the form of flexible leads or cords in order that the receiver maybe conveniently held to the ear or carried on the head in the form of aliead set and the exploring coil and test clips ma- I nipulated asthe situation demands.

In whatever manner'the apparatus may be mounted, for convenience in use, I prefer to make the exploring coil in the form 'sub stantially as shown in Figs. 2 and 3 and to use anarrangement for carrying it and its flexible connection or cord' on the casing or.

1 whatever form of mounting is providedfor the apparatus.

This exploring coil consists of an oblongclectromagnct-orcoil 50 hav ng a core 51 and upper and lower iron pole pieces or pole facesv52 and 53 extending the ength of the oblong coil as shown in dotted'lines in Fig. 2. The windings of the electromagnet 50 are covered or incased on the outside with a suitable protective covering, preferably thin leather or kid, to prevent chafingof the insulation of the outer layer, such covering being suitably water-proofed as with shellac or varnish. The magnet spool with its iron polefaces 52-53 is clamped to a metallic holder 54 of L-shaped. cross-section extending the length of the magnet, by means of suitable bolts 55 which extendthroughthe ing the handles 71-72 to open the jaws of 7" ingfterminals are electrically insulated from the nuts and bolts in a well known manner, v i

not shown. The terminals of the magnet are connected with the connecting terminals as indicated in dotted lines at and 61,

while the leads 45 and 46 are; connected to the connecting terminals by means of binding screws 62 and 63, respectively. The coil, as a whole, is carried'on one of the jaws 64 of a spring clip '65, being held thereon by means of belts or screws 66. The other jaw 67 of the spring "clip engages the side of the magnet, the adjacent side of the magnet being provided with a longitudinal groove 69 to receive and hold a wire or conductor between the magnet and the jaw 67. The spring clip 65 here shown is of a standard typefin which the 'aws are held together under tension of a c amping spring 7 O in the form of a split cylinder, portions of the jaws being extended down to form handles 71 and 72 by which the j aws may be opened against the tension of spring 70. In use the coil is clamped on the wire being tested by operatthe clip, inserting the wire between the 'insulated jaw and the coil with the wire resting in the groove 69 and then releasing the han dles to permit the jaw 67 to hold the wire up against the side of the magnet in the groove so that it will lieparallel to the windings of the coili- 'The spring clip here shown is of a well known formof paper clip oribinder, v an important requirement being that it bev madev 01E iron, whereby when the jaw 76 is closed against the coil 50 with the wire to be tested clamped therebetween the coil and. the portion of the wire so clamped will be surrounded by a wall of magnetic'material consisting of the top and bottom iron ole pieces or , pole shoes 52 and 53 and the iron jaws 64' and 76 of thespring clip, thus acting to form a closed magnetic circuit for the,

. coil and prevent outside circuits from havin any inductive efl'ect on thecoil winding. Referring nowto'Fig. 4, 77 indicates a portion'of the side wall of a box or other mounting for'the apparatus of the test set to which is secured the coil and cable holder 78 comprising an oblong head piece 79 spaced from the mounting member 77 by a pair of postssuch as 80 near ear-h end of the oblong head member, the parts being held in therelation shown by means of suitable screw s o'r'b'olts 81 passing through the head and the centers of the posts into the mountingimember77. The coil and cable are carried by the holder in the manner shown in Fig. 4. The cable comprising the twisted pair of conductors 44-45, when not 1130 in use, is held in place by coiling it around the posts. 80 between the mounting member and the head 79 as shownin the drawing,.

the coil being held by passing the handles 71 and '72 down over the twisted pair 44-45 and the head 79 as shown in the drawing, one handle being wedged between the coil formed by the twisted pair and themounting member 7 7 and the other handle resting 10 against the outer face of the head 79, the

.. parts being so arranged that the handles- '11 therefore claim the same as part of my invention.

In using the device, the the receiver on his head, the receiver being preferably provided with the usual form of head clamp for this purpose, and iftesting for a ground on a metallic circuit, one of the test cli' s, for example 48,is connected to a groun wire or other good ground connection" and the other clip 47 connected first to one line and thenthe other. With each ofthe two latterconnec'tions, the lineman operates the generator, whereupon a ground ed or closed circuit will be indicated by part- "of the generator current flowing through the receiver, the path of which may be traced as follows: From armature winding 11 of the generator, brush 13, conductor 14, test clip 47, over the line being tested through ground to test clip 48, conductor 32, normallvclosed '40 contacts 25-26, conductor 31, receiver 16,

conductor 30, normally closed contacts 23-24, conductor 29,- vcontacts 3-2 to generator,.'part 'of the current being shunted through the resistance 35 by way of contacts 532. The presence of a ground being thus detected, the exploring coil is clamped on the'wire in trouble and the generator again operated with the push button 38 closed which closes the normally open contacts: 26-36 and .2437. If no tone is I noticed in the receiver, the exploring coil is.

removed and clamped to the same wire but to the other side of the .test clip 47 and if a tone is thenh'ea-rd in the receiver it indi- 5 5 catesthat the'grouiid .is on that sideof the test clip. Thus, if the tone is. heard when the coil is clamped to one side of the clip and not on the other, the direction of the (troubleis toward the finder coil ,where the 6D- tone. is heard. Thistone is produced by a current induced in the finder coil- .-which traverses the following path: From finder coil 41 over conductor40, contacts26 36,"

conductor-31, receiver -16,' conductor 30, contacts 24-37 and conductor 42 back to lineman places point where the ground fault was found to the finder coil, the circuit of the shunt coil 35 now being open at contacts.23-24. ,The current in the finder coil 41 is induced fronan alternating current passing through the line. wire to which the coil is clamped, for example 43 indicated in dotted lines. This is a special form of test current produced in the operation of the generator and having certain advantageous qualities resulting from the novel combination and arrangement' of circuits and apparatus. here disclosed.

The circuit of the test current may be traced from generator winding 11, brush 13, conductor 14, test clip 47, line conductor 43, ground fault G, through ground to test clip 48, condenser 2O, conductor 21, resistance 35, contacts 532, and back to generator, the winding of the generator being shunted at each half revolution of the armature by way of intermittent contacts 7 -9, conductor39, contacts 26-36, conductor 31, resistance 35, contacts 5.3--2 to generator frame.

' As before stated, this closureofthe interof the generator is reached. This shunting' out of the generator reduces the resistance of the test circuit by removing the generator therefrom and at the same time p'ermitting'the condenser to 'dischargehack over the circuit being tested, the discharge circuit being traced from condenser 20, over conductor 46, test clip 48, through ground to'ground fault G, thence over conductor 43, test clip 47, conductor 14, brv'sh contact 13, intermittent contacts 79, conductor 39, contacts 2636, and back to condenser 20. It will be seen that this shunting of the generator and discharge of the condenser will effect an instantaneous alternation of the current thus producing a sharp peak in the current curve which makes for maximum efii ciency in the inductance effect of the test current on the exploring coil. It will be seen from the above that two impulses will be produced for each half revolution of the generator armature. H

The lineman perceiving the tone in the re ceivercontinues to move the exploring coil and test clip 47 along the 'wire at increasing distances from the point where the test clip 47 was first placed in a direction toward the exist. This exploration continues until no tone is audible in the receiver when the generator is operated, which indicates that the exploring coil is-at or past the location of the ground fault, assuming of course that the circuit beyond Fis bpen and that the ground fault is the only one. v

The lineman may locate the point where two line conductors are crossed with the method above described for locating the ground (fault, except that the test clips 47,48 are connected one to each-of the lines and-the exploring coil placed on one of the lines, and the exploration continued until the place where the lines are crossed is reached.

, In testing for shorts, the method is thesame, except that the lineman knows with-" out testing which lines are crossed or shortcircuited and simply proceeds to trace the path of the test'circuit with the finder coil to the point where the fault exists.

The lineman will be able to tell whether the line is open without resorting to the -use of the exploring coil, by simply plaping the receiver to his ear'and operating the generator. No sound will be heard in the-'- receiver if the line is open, while it it isclosed, a portion of the generator. current will flow through the receiver giving the indication of-the closed circuit. From 'experie'nce the lineman will be able to jud e with fair accuracy the distance to the troub l by" the volume of sound produced in the receiver. This is especially true in locating trouble on copper toll lines.

if the defect-is so far away that the lineman can hardly perceive the tone in receiver, the

' distance is the equivalent of fifty miles of No. 10 B & S copper metalliccircuit. As

he gets closer 'to the trouble the tone gets louder and as he gets beyond, it such will be indicated by a low tone.

To talk withthe set, the clips are connected across the line conductors or'in the line circuit and the push button 33 closed, theclosure of the button 33 completing the battery supply circuit for the transmitter and the primary winding of the induction coil.

.By using a high resistance receiver and exploring coil for testing, the same receiver may be used'i'or talking which enables the use of the set to be quickly-changed from that of a testing set '.to a portable-telephone set by simply operating the keys orbuttons In the location of swinging shorts the high potential caused by the discharge of the condenser brings the swinging shortcircuiting connection into CIICUIt, even though the contact may be a poor one and of' high resistance, so that it can be located.

While; I have herein described and illustrated. a specific embodiment of my invention, it is to be understood that. I do not limit myseli to such specific. form, but contemplate all such modifications and variants thereof as fairly fall within the scope of the appended claims. V

Having-thus described my invention what I claim and desire to secure by Letters,

1. In an electrical testingjsystem, a condenser and amagneto generator arranged to be connected in series with a circuit to be For example, 7

tested, m eans operated in unison with the generator to shunt the 'enerator out of aircuit near a period of high power output of the generator, and means "for detecting the presence of. the current so produced in the circuit.

2. An electrical testing system as'defined.

in claim 1 in which the generator is inter- 'mittently shunted out of circuit while main-4 taining the condenser in series with the said circuit to prevent the flow of direct current throu h said circuit.

'3. 11 an electrical testing system, a con denser and a magneto generator arranged to beconnected in series with a circuit to be tested, and circuit controlling meansop'er able in unison with the generator to cause said condenser to be charged and discharged in series with the said circuit and to shunt said generator out of circuit during d1S charge of the condenser.

i 4. An induction explormg, coil having an iron'core and winding therefor, magnetic iron pole pieces for said core, a returnyoke of iron connecting said pole pieces across one side of said coil and forming a magnetic yoke or return connection and a second mag mounting means, an exploring coilhaving flexible leads secured at one end to the mounting means, a stationary reel carried by said mounting means arranged to, receive the flexible leads of the exploring coilzcoiled to hold the coil in place, a casing of magnetic material .surrounding the sides and polar ends of said exploring'coil, having one side movable to admit a conductor within the casing between the coil and-the movable -side,'spring clam-ping means tending to hold thereon, a head member onsaid-reel arranged H said casing closed, anda pair vof levers or handlesconnectedone with the casing and the other with the movable side forfopening and closing said casing against the tension of said springclamping means, said handles projecting from said coil and being arranged to straddle said flexib1e=1eadfcoi .reel head and to be heldin clamped engagementtherewith on the mcunting'means.

6. .In an electrical testing system, a .talk-' ing set including aninduction ,coilyreceiver transmitter and battery, an ,explor1n'g coil and switching means for alternately co mectand said ping and disconnecting said receiver with the 'remainder of said talking set and said .ex-

ploring coil.

7. An electrical testing system as claimed in claim 6 having a telephone magneto generator and a pair of testing leads connected in series with the receiver and means for shunting the receiver. through a predef with the exploring coil and to short-circuit connect the condenser in 'series with the generator upon connection of the receiver the] terminalsotthe condenser when the receiver is connected with the armature of the talking set.

*9. In an electrical testing system, a talking set including a transmitter, a circuit therefor and a receiver and receiver circuit inductively connected with said transmitter circuit, a magneto generatorand means operable upon operation of the generator to disconnect the receiver circuit from inductive relation with the transmitter clrcint and connect the generator circuit with the re: CGIVBI' clrcuit.

In testimony whereof I aflix my signature.

. -.OLARENOE A. ANDERSON. Witnesses; l

. .R. MoDAmEL,

CLARENCE WILSON.

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