US1845081A - Electrical protective system - Google Patents

Description

Feb. 16, 1932. L.P. FERRIS ELECTRICAL PROTECTIVE SYSTEM Filed Aug. 22. 1930 Patented Feb. 16, 1932 UNTED STATES PATENT OFFICE LIVINGSTON I. FERRIS, OF MONTCLAIR, NEV JERSEY, ASSIGNOR TO AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK selves.

ELECTRICAL PROTECTIVE SYSTEM Application filed .August 22, 1930. Serial No. 477,124.

This invention relates to electrical protective systems. More particularly this invention relates to arrangements for simultaneously grounding a plurality of circuits when induced voltages become impressed thereon.

A pair of protective blocks each having an air gap which breaks down at a predetermined potential have recently been used in the telephone art for the protection of each of a number of telephone circuits from high voltages set up therein by one or more sources extraneous to the circuits them- A resistor or a saturating reactor may be interposed in the ground connection of each pair of such protective blocks. The resistor or the reactor as the case may be, will carry the operating current of the two blocks associated therewith and the impedance drop across it may be rectified by a rectifier of, for example, the copper oxide type. The rectified current may be applied to a relay employed to shunt both protective blocks, in which event the induced current or currents will be carried through the heavy i' duty contacts of the relay.

A pluralty of pairs of protective blocks and a plurality of relays each corresponding to one of the pairs of the protective blocks,

may be associated with a plurality of telephone circuits running substantially parallel to each other, each exposed to the same inductive effects. Apparently it will be possible to have a condition where some of the various relays will be operated and some unoperated, because the inductive effect may not be sufliciently large to cause all of the associated protective blocks to operate. This condition creates a great hazard since the vcircuits connected to the protective blocks with particularity in the appended claims, A

the invention itself will be better understood from the detailed description hereinafter following when read in connection with the accompanying drawings showing three ligures embodying the elements of the invention which are given merely for the purpose of illustration.

Referring to Figure l of the drawings, the reference character Ll designates a pilot wire which is divided into a plurality of sections only one of which will be considered in some detail hereinafter. The distant end will be grounded and the nearby end will also be grounded through a resistor or saturating reactor RO. This section of the pilot wire may be grounded at, for example, two successive protector poles. It will be apparent that the reactor RO will be part of another section of the pilot wire which may extend to a third protector pole. It will be further apparent that each reactor may be placed at or near the center of each section of the pilot wire7 if desired.

lVhen a nearby power circuit or other eX- traneous source induces a voltage in the pilot wire L1, a current will be transmitted through the nearby reactor R0, which will be utilized in this invention to simultaneously ground a plurality of circuits which may run parallel to eachother and thereby obviate any electrical hazard resulting from the failure to ground any one of the various circuits.

rlhe reactor R0 is bridged by a circuit which includes two rectifiers l)1 and D2 both of which may be of the copper oxide type. The conductor common to rectifiers D1 and D2 is connected to the midpoint of the reactor RD through the winding of a relay W0 and a resistance Z1. The relay W0 includes two armatures Al and A2 and these are nory mally released. Armature A1 and its con- Vso tact are in shunt with a portion of resistance Z1. Upon the operation of the relay YV() the shunting of a portion of the resistance in series therewith will have the eect of increasing the flow of current therethrough, and this feature of the invention will be described in greater detail hereinafter.

One or more two-wire telephone circuits may be supported at each protector pole. rlwo such telephone circuits designated L10 and L20 are associated with the local protector pole, and one or more circuits each similar to the one designated L10 may be associated with the next successive protector pole. The apparatus associated with the circuit L10 will be described in some detail hereinafter merely for the purpose of illustration, although it will be understood that similar apparatus may be associated with each of the other circuits such as L20, etc.

The circuit L10 is bridged by two protective blocks connected in series relationship. Each of these blocks includes two carbon electrodes spaced from each other by a gap of, for example, .005 inches'. The electrodes forming one of these protective blocks will be designated O1 and O2,and those forming the other block will be designated O2 and C1. Each of the electrodes O1 and O1 may be supported in a porcelain holder which is so shaped as to insure the normal existence of a gap of predetermined width between the component electrodes.

The conductor common to the two protective blocks is connected to ground through a resistor ora reactor designated R2, a reactor being selected for illustration. The reactor R2 is bridged by a circuit including two rectiiiers D3 and D1 which may, if desired, be of the same general type as rectitiers D1 and D2. A winding B1 of an associated relay designated W2 is connected between the midpoint of reactor R2 and the conductor common to the rectiiiers D3 and D1. The winding B2 of this relay is in'series with the armature A2 and the associated contact of relay 70. lt is to be noted that the winding B1 of a relay W2 associated with the circuit L20 is also connected in series with the winding B2 of relay W1 and with the armature A2 and the `associated contact of relay W0. It will be understood, however, that the corresponding windings of relays similar to vW1 which are'located near other protector poles may be connected in series with winding B2, if

deemed necessary.

Vhen an induced voltage of a predetermined magnitude or of greater magnitude becomes impressed upon the'circuit L10, an

arc will be formed between the carbon electrodes C1 and C2 and between electrodes O0 and O1 ot the two protective blocks associated with the circuit. The currents established through these protective blocks will be transmitted to ground through the reactor R2. Opposite halves ot the alternating voltage impressed across the reactor R2 will be recti-f tied, device D3 rectifying, for example, the

positive half of each cycle ot the voltage, and

the device D1 rectifying the negative half of tures A3 and A1Vor relay -TW1 will be of heavy duty type so as to conveniently transmit large currents. Y

rlhus, it will be apparent that the impression of an induced voltage upon circuit L10 will operate thetwo protective blocks associated with that circuit, thereby operating the relay W71, and then the armatures A3 and A1 of relay N1 will shunt these protective blocks. By preventing current from being` continuously discharged through these protective blocks, the formation of irregularities upon the carbon electrodes thereof tend-- ing to reduce the size of the air gaps will be substantially reduced, and therefore these protective bloclrs will have longer lite. lt will be understood that the relay V171 will be released when the previously induced voltage has disappeared.

rlhe reactor R0 located in series in the pilot wire L1 and its associated circuits represent primary features of the invention employed for simultaneously grounding the circuits L10 and L20. A voltage induced in the pilot wire L1 will cause the impression ot a corresponding'voltage between the terminals of reactor R0. Opposite halves of each cycle of the impressed alternating voltage will be rectitled by rectitiers D1 and-D2, and therefore a direct current will iiow through the winding of relay `W0 and resistance Z1 causing rclay `W0 kto operate. lnasmuch as the windings B2 and B1 of relays W1 and 72, respectively, are connected in series with the armature A2 of relay N0 and its contact, the closure of the latter Contact will cause both of these relays to become simultaneously operated'. Hence, the armatures A2 and A1 of relay lll will be attracted and these will connect the conductors connected to the carbon electrodes C1 andV O1 of the two protective blocks associated with circuit L10 to ground through the reactor R2. Thus, the circuit L10 will beefectively grounded.l Similarly, the operation of relay W72 will cause the eiective grounding'of the circuit L20, the grounding circuit or circuits being similar to those associated with the circuit L10. Y nasmuch as the armature A1 of relay W0 closes its associated contact just as soon as the armature A2 of that relay closes its contact, a substantial portion of the resistance Z1 will be shunted so that a greater current may tend to low through the winding of relay WVO. Under any other conditions the rectified current provided by rectifiers D1 and D2 may not be suicient to operate relays 71 and 72 and maintain these relays operated.

While the windings B2 and B,1 have been shown as connected in series relationship with the armature A2 of relay W0 and its contact, it will be understood that these windings and other similar windings, may be connected in parallel relationship, or that some may be in series relationship and other in parallel relationship, within the scope of this invention.

Fig. 2 of the drawings represents a modified arrangement for obtaining the simultaneous grounding of a plurality of circuits which may run parallel to each other. Here each section of the pilot Wire includes two reactances, one located at each protector pole. Thus, the reactors Ro and R10 are located in series with the section of the pilot wire designated L1 at distant ends thereof, which are grounded. The reactor R20 is connected to the section of the pilot wire designated L2 which extends to a distant protector pole, while the reactor R30 is connected in series with the section of the pilot wine designated L3 which extends to a more distant protector pole. The terminals of each of the various reactors R0, R10, R2o and R30 are connected in a circuit which includes a pair of copper oxide rectiiers similar to those designated D1 and D2 in Fig. 1 of the drawings, and, moreover, a master relay and a resistance similar to those respectively designated and Z1 in Fig. 1 of the drawings, are connected to each of the various reactors.

The object of the arrangement shown in Fig. 2 is to cause the simultaneous grounding of the various circuits at any particular protector pole when an extraneous voltage is impressed upon either section of the pilot wire terminating at that particular protector pole. Thus, it is proposed to have the various relays associated with the corresponding circuits supported by any protector pole become simultaneously grounded if an induced voltage flows through either of the two reactors such as R0 and R20 which are connected to circuits forming part of the equipment at that protector pole.

lt will be apparent from Fig. 3 that a relay VV2 similar to the one designated V1 in Fig. 1, but having three properly poled windings designated B5, BG and B7, will be needed for each circuit requiring protection. One of these windings, i. e. B5, will be connected to the two copper oxide rectiiers, such as D3 and D4 ofhFig. 1, forming part of the equipment for locally protecting one of the various circuits which may become exposed to extraneous voltages, another, i. e. BG, will be 1 connected in series with the two parallel rectiiiers D1 and D2 bridging the reactor in one section of the pilot wire, and the third, i. e. B7, will be connected in series with the parallel rectiiiers D5 and D6 bridging the reactor in series with another section of the pilot wire.

While this invention has been shown in one particular embodiment merely for the purpose of illustration, it will be understood that the general principles of this inventiony may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope oi. the appended claims.

What is claimed is:

1. The combination of a plurality of circuits exposed to extraneous inductive effects, a pilot wire exposed to the same inductive effects, an impedance in series with said pilot Y wire, and means including rectifying apparatus extending from said impedance to said circuits and responsive to a substantial extraneous inductive effect for simultaneously grounding all of said circuits.

2. The combination of a plurality of circuits exposed to extraneous inductive currents, a pilot wire exposed to the same inductive currents, a reactor in series with said pilot wire, and means including a pair of tective blocks being employed to ground the y various circuits when an extraneous voltage becomes impressed thereon, a pilot wire eX- posed to the same extraneous voltage, and means responsive to any extraneous voltage impressed on the pilot wire for simultaneously grounding all of said circuits independently of said protective blocks.

4. A system for simultaneously grounding all of the circuits extending over protector poles when a high voltage from one or more extraneous sources becomes impressed on the system, comprising a pilot wire grounded at each end, a resistor connected in series with said pilot wire, two rectifiers connected in a circuit in shunt with said resistor, said rectiiiers being poled so as to rectify opposite halves of any alternating voltage impressed upon said resistor, a plurality of relays one associated with each of the various circuits, and means interconnecting the various relays with said rectiiiers for simultaneously operating said relays When a substantial alternating voltage is impressed across said resistor.

In testimony whereof7 I name to this specification August, 1930.V

LIVINGSTON P. FERRIS.

have signed my this th day of

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