US2032513A - Electrical protective system - Google Patents

Description

Fil ed March 14, 1935 z Sheets$heec l INVENTOR i '2 ,3 B! V ATTORNEY arch 3, 19%. L. K. SWART fi p ELECTRICAL PROTECTIVE SYSTEM Filed March 14, 1935 2 Sheets-Sheet 2 Ejecondar of EMF/I751- 5225513332 R circuit. m-iq 7b Winding; 49 lelay R10 49320- ll; B Battery.

Slow operzztlflg re ay INVENTOR ZESW i ATTORNEY Patented Mar. 3, 1936 ETED STATES PATENT OFFICE ELECTRICAL PROTECTIVE SYSTEM Applicaticn March 14, 1935, Serial No. 11,177

7 Claims.

This invention relates to electrical protective systems or more particularly to arrangements for simultaneously grounding a plurality of conductors when induced voltages above a fixed and 51 predetermined value become impressed thereon. The arrangements of this invention also are adaptable for the purpose of testing the apparatus and in the testing operations potentials may be applied either to the various conductors and ground or to the conductors alone.

Pairs of protector blocks each having an air gap which breaks down at a predetermined potential are used in the telephone art to protect each of a number of telephone conductors from 15 high voltages set up therein by one or more sources extraneous to the circuits themselves. In these arrangements a resistor, saturating reactor or transformer is interposed in the ground connection of each pair of protector blocks or in :0 the common ground connection of all protector blocks. In some arrangements the current derived from the impedance drop across the resistor, reactor or transformer, is rectified by a copper-oxide type of rectifier. This rectified our- 35 rent is applied to a relay which when operated shunts a pair of protector blocks or, if desired, the rectified current may be caused to operate a relay which will apply local battery to a group of short circuiting relays, employed for short cir- 30 cuiting all the protector blocks during the period in which the extraneous voltage exists. In another type of relay protector arrangement the current traversing one or all of the protector blocks may be applied to a saturating reactor or transformer which operates an alternating current relay the contacts of which apply local battery to a multiplicity of short circuiting relays. The contacts of these relays short circuit all of the protector blocks, thus preventing permanent grounding of these blocks.

At present the commonly employed low voltage carbon protector blocks have a considerable variation in operating range depending upon the history of previous operation of the blocks, the impedance of the line, the humidity, etc. In order to provide operation of protective equipment at a predetermined fixed value of voltage, the carbon protector block alone can not be depended upon to give operation within a narrow margin of operating voltage. If a gas discharge device, however, is shunted around the protector block in series with a relay, condenser, etc, as will be described hereinafter, a fixed operating voltage, depending on the design of the tube may be obtained. This operating voltage can be made to lie slightly above the normal telegraph and ringing voltages applied to the line conductors and considerably below the 250-volt minimum of a carbon protector block. Furthermore, by the use of gas discharge devices it becomes practicable to operate the device from voltage applied to a line wire from a remote point. A particular protective device situated along an open-wire line can be selected for operation by knowing the conductors on which the various gas discharge devices are applied. Furthermore, remote testing may be carried out by applying voltages between wires equivalent to the voltage required to operate the device from a single conductor to ground. When testing by application of voltage between the conductors, the voltage to ground will be one-half of that required to operate the device from a single conductor to ground, as will be shown hereinafter. Thus, there will be a very wide margin in the operating voltage of the device. This is of decided advantage due to the very wide operating values to be expected of carbon protector blocks some of which as before stated, might operate at a very low voltage and ground in the process of testing. This results in lost service time and necessitates sending an attendant out to some remote point to replace the blocks before the circuits can be restored to normal.

At times it may be desirable to provide for remote testing and yet not employ the gas discharge devices to operate from voltages to ground but from voltages between line Wires only. This is readily accomplished by the apparatus of this invention, as will be shown thereinafter.

This invention will be better understood from the detailed description hereinafter following when read in connection with the accompanying drawings in which Figure 1 illustrates a plurality of adjacent conductors two of which are respectively connected to networks of gas-filled tubes and relays; Fig. 2 illustrates a modification in which the two relays of Fig. 1 are replaced by a single relay; Fig. 3 illustrates a biasing arrangement of batteries connected between two of the conductors, the arrangement also including two oppositely directed gas-filled tubes; Fig. shows the two conductors connected by a single tube and a single biasing battery; Fig. 5 illustrates a modification which includes a trigger tube of the threeelectrode type; and Fig. 6 shows another modification which includes two tubes and one of the windings of an associated relay connected in series with each other between the two parallel conductors.

In Figure 1 reference characters W1 to W4, inclusive, represent four of a plurality of conductors or circuits which may be supported by a common protector pole. Each of these conductors may be connected to ground through an individual protector block and a common reactor or saturating transformer T, as shown. The various protector blocks are designated P1 to P4, inclusive. The lower terminal of each of these blocks is connected to the upper terminal of the primary winding L1 of the transformer T. Each upper terminal of these protector blocks is connected to conducthe relays R10 and R20.

tors W1 to W4, as shown. Each of the various protector blocks may include two carbon electrodes spaced from each other by a gap of predetermined width.

The transformer T includes also a secondary winding L2 which is connected to the respective upper windings of relays R1 and R2. Each of these connections may or may not include a series condenser. The condenser if desired can be used to tune the circuit of the upper winding of the relays R1 and R2 to some definite frequency such as that of some nearby source of extraneous induced potential.

The relays designated R10 and R20, associated with the protector blocks P1 to P4, inclusive, are arranged so that their windings are connected in parallel, the parallel circuit being in series with a battery B and the armatures and contacts of the relays R1 and R2. When either or both of the relays R1 and R2 become operated, current will flow from the battery B over the armatures and contacts of these relays and through the windings of The armatures of these latter relays will become simultaneously attracted to their contacts and will simultaneously shunt all the protector blocks. They will also shunt the gas tube devices connected thereto and extinguish the tubes, as will be shown hereinafter, and at the same time shunt the arc across all of the protector blocks P1 to P4.

In addition to the above described relay equipment a pair of conductors, such as W1 and W2, which traverse the entire exposure are chosen as pilot conductors to which are applied at a given protector point condensers, gas discharge tubes, resistances, etc., which will now be described. A condenser C1 is connected to conductor W1 and to the anode of rectifying gas tube N411 and to the cathode of rectifying gas tube N421. The cathode of the gas tube N411 is connected to the cathode of the rectifying gas tube N441 and to lower terminal of winding l of the relay R1. The upper terminal of the winding I of relays R1 and R2 and the lower terminal of Winding 2 of these relays are connected to each other as shown. The upper terminal of winding 2 of relay R1 is connected to the anodes of rectifying gas tubes N421 and N421. The anode of gas tube N441 is connected to the cathode of gas tube N431 and to ground. Gas tubes N411, N421, N431 and N441 are shunted respectively by resistances Z and these are of equal value if these gas tubes have equal breakdown potentials. The values of each shunt resistance Z should be of the order of from 500,000 to 1,000,000 ohms or higher depending on the leakage between the elements of the gas tubes. The conductor W2 is connected to a similar arrangement except that the relay R2 is associated with this second arrangement. Windings 3 of both relays R1 and R2 are connected to the secondary winding L2 of the transformer'T.

The operation of the protective device from extraneous potentials is as follows: Assume that the polarity of the applied potential is such that conductors W1 and W2 are positive to ground. On one arrangement current will fiow from conductor W1 through condenser C1 through the elements of gas tube N411 and its associated resistance to winding l of relay R1, thence through winding 2 of that relay and through the elements of gas tube N431 and its associated shunt resistance to ground, resulting in operation of relay R1, the contacts of which apply current to the short circuiting relays R10 and R20. results in a short circuit of all of the protector blocks P1 to P4 and the gas tube arrangements connected thereto, and current flowing from the various conductors W1 to W4 traverses the Winding L1 of the transformer T and passes to ground.

Winding L2 of transformer T, by virtue of its connection to windings 3 of relays R1 and R2 will, therefore, operate or hold operated both of these relays for the duration of the extraneous potential. The only potential existing across the gas tube arrangements and conductors W1 to W4 after operation of relays R111 and R20 will be that due to the voltage drop in primary winding L1 of transformer T. This voltage will be but'a few percent of that required to keep the glow present in the various gas discharge devices and hence these gas tubes will be extinguished.

For a potential between conductor W1 and ground of the opposite polarity the operation will be as described with the exception that the current will pass from ground to the element of the gas tube N441 and its associated resistance, through windings l and 2 of the relay R1, thence through gas tube N421 to the condenser C1 and thence to conductor W1. The operation as described with respect to the gas tube arrangement involving condenser C1 applies equally well with respect to the gas tube arrangement associated with condenser C2.

Where it is desired to test the relay protector equipment by applying potential at some remote point, potential may be applied between conductors W1 and W2, the mid-point of the source of potential being grounded. Operation of relays R1 and R2 is brought about as follows: Assuming the potential applied to conductor W1 as positive and that applied to W2 as negative, current will flow from conductor W1 through condenser C1 through gas tube N411 and its associated shunt resistance, through the Winding I of relay R1, through winding 2 of relay R2 to gas tube N422, condenser C2 and thence to conductor W2. Operation of the relays R1 and R2 is also brought about by reversing the potential applied between conductors W1 and W2 in which case current will pass from conductor W2 through condenser C2, gas tube N412, winding l of relay R2, winding 2 of relay R1, through the gas tube N421 and its associated resistance, through condenser C1 and thence to conductor W1. This will ordinarily result in the operation of both relays R1 and R2. Thus, it will be noted that the voltage required to operate the gas tube arrangement by applying voltage between conductors W1 and W2 is equivalent to that required to operate the arrangement when that potential is applied between the conductor and ground. But the potential to ground applied between these conductors is only onehalf of the potential between wires.

Fig. 2 shows an arrangement similar to the one described with respect to Fig. 1. The two relays R1 and R2 have been replaced by a single relay R3. This relay has a winding 3 which is connected to the secondary winding of transformer The operation of said latter relays T and it also includes two pairs of windings numbered ii and 2| and I 2 and 22 which correspond to the windings l and 2 of relays R1 and R201 Fig. i. The operation, however, is identical to that as described with respect to Fig. l.

In Fig. 3 operation of the relay protective device is brought about by the breakdown in the aps of any one of the protector blocksor by voltages applied between two selected conductors such as W1 and W3 or by the voltage applied between any one of the conductors and ground. Biasing batteries A1 and A2, so poled as to increase or decrease the potential required to cause a dim charge between the gaps of the tubes N41 or N42, are connected respectively to the anode of tube N41 and the cathode of tube N42, as shown. The mid-point or common terminus of these batteries is connected to the conductor W1. The operation of the gas tube arrangement takes place as d scribed previously and therefore need not be repeated. But one-quarter of the number of tubes are required however, and by means of the bias of batteries A1 and A2, the operating vo tage or" these tube devices can be altered as desired.

Fig. 4 shows another a 'rangement for accomplishing the same result using but a single gas tube which operates the relay R5 when the potential applied to conductor W2 is sufiiciently positive and that applied to conductor W1 is negative; or if conductor W1 is rendered negative and the ground is rendered positive. The arrangeis biased by battery A which may be employed either to increase or to decrease the operating voltage of the gas tube N4. A condenser may, if desired, be connected across the lower winding of relay R5 for tuning its circuit for op eration at a particular frequency.

Fig. 5 shows another arrangement for short circuiting conductors W1 and W2 upon the application of sufficiently high potentials to either or both of these conductors. This arrangement includes a gas discharge device operating on the trigger principle and it is actuated by potentials applied either between the conductors W1 and W2 or between conductor W1 and ground. The relay protector device will of course also operate from currents through the protector blocks due to potentials applied between the conductors and ground.

Conductor W1 is connected to condenser C1, the other side of said condenser being connected to the auxiliary electrode of gas tube N5. The cathode K of the gas tube N5 is connected to the upper terminals of condenser C2 and winding 2 of relay R5. The other terminals of condenser C2 and winding 2 of relay Rs are connected to a source of potential B, the other side of which is connected to the armature of relay R7. The contact or relay R7 is connected to the anode A of gas tube N5. The windings of the short circuiting relay R10 and of relay R7 are both connected to th armature and contact of relay Rs through local battery B.

The operation of the device is as follows: Voltage applied between conductors W1 and W2 or between conductor W1 and ground through conden er (31 if of sunicient amplitude to cause glow to take place between the electrodes of the gas tube N5 causes current to flow in the circuit which includes the anode A and the cathode K of the tube N5, winding 2 of the relay R6, battery B, the armature and contact of relay R7 and thence back to the anode A of the gas tube N4. This current brings about operation of the relay R6, causing its armature to be attracted to its contact. The cloplied between conductors W1 and W2 or between conductor W1 and ground will hold relay Rs in the operated condition. The armature of the relay R7 will be h ld away from its back contact during the period which the relay R6 is operated. Upon withdrawal of potential from the conductors and ground, relay R6 will restore to normal the consequent restoration of the relays R19 and R7 to normal. The latter relay R7 will reapply battery otential to the anode A of the gas tube N4.

t will be understood of course that the relay Rs may be of the multi-contact type to provide short circuiting paths for protectors P1 to P2, if so desired, in which case the relay R10 may be dispensed with. The arrangement is described only for a. pair of wires W1 and W2 but it is equally applicable to a multi city of conductors. Another and varied arrange ut for providing protector operation applica on of potential between a pair of conductors disclosed in Fig. 5. Conductor W1 is conneo ed to a condenser 01 in series with a pair of gas tubes N21 and N22 which are shunted by resistances R1 and R2, respectively. These elements are in turn connected in series with winding of the relay Re and with conductor W2. Conducto s W1 to W4. inclusive, are connected to protectors P1 to P4, a transformer T and the winding i of relay Re. The short circuitin relays R10 and R20 are controlled by relay R6 and battery 3 supplies the current necessary for their operation.

The operation of the arrangement for potentials applied to conductors W1 and W2 is as follows: Potential of sufiicient amplitude to break down the gaps or both gas tubes N21 and N22 but of insufiicient amplitude to operate protectors P1 to P4, inclusive, passes current through winding '2 of relay Rs brings about its operation. Relay Rs operates r lays R10 and R20, the armatures and contacts of which short circuit protectors P1 to P4 in the normal manner.

The low impedance paths etween the conductors and ground through the armatures contacts of relay R10 and R2u and the primary winding of transformer T provides means for holding the relay R6 in the operated condition by virtue of the connection of its windin l to the primary winding of transformer T. Relays Re and R10 and R20 will be held operated during the period in which suincient potential exists between any one or all of the conductors and ground, but these relays will restore to normal immediately upon withdrawal of this potential. The gas tube discharge devices 1 21 and N22 are, therefore, required to carry current only for the period of time required to operate relay R6 and relays R10 and R20. Resistances R1 and R2 are applied to tubes N21 and N22 for the purpose of insuring a definite breakdown potential for these series connected gas tubes. if but one tube is required, resistances R1 and R2 may be omitted. It will also be understood that relay R may be of the multi-contact type, thus performing the functions of relays R and R20, etc., and, moreover,

that the number of conductors so protected need not be restricted to four as indicated but may consist of a considerably greater number, if so desired.

In each of these arrangements where the circuit is tested by applying a voltage between two conductors, such as W1 and W2, the testing voltage should preferably be applied through a transformer, the secondary of which is connected to these conductors and the midpoint of which is grounded. If desired, the transformer may be replaced by a resistor or any other impedance or reactance the midpoint of which is grounded.

While this invention has been shown and described in certain particular arrangements merely for the purpose of illustration, it will be understood that the general principles of this invention may be applied to other and widely varied organizations if departing from the spirit of the invention and the scope of the appending claims.

What is claimed is:

1. Apparatus for the protection of a plurality of signaling circuits, comprising a pair of gasfilled rectifier tubes connected in opposition between two oi the signaling circuits so that alternate half cycles of voltage impressed between the said two signaling circuits will be transmitted through said tubes, and means responsive to the operation of both of said tubes for simultaneously grounding all of the signaling circuits.

2. Apparatus for the protection of a plurality of conductors, comprising a pair of gas-filled rectifier tubes, a pair of sources of potential, each of the tubes and each of the sources forming a series circuit bridging two of the conductors, and means responsive to the operation of said tubes for simultaneously grounding all of the conductors.

3. Apparatus for the protection of a plurality of exposed conductors comprising a pair of gasfilled rectifier tubes, a relay having two windings each of which is connected in series with one of the tubes across the same pair of exposed conductors, and means responsive to the operation of said relay for simultaneously grounding all of the exposed conductors.

4. Apparatus for the protection of a plurality of exposed conductors, comprising a plurality of protector blocks one terminal of each of which is connected to one of the exposed conductors, a saturating transformer the primary winding of which is connected between the other terminal of each of the protector blocks and ground, a relay having three windings one of which is connected to the secondary Winding of said transformer, a pair of gas-filled rectifier tubes connected in mutual opposition across the same pair of exposed conductors, each of said tubes being connected to one of the remaining windings of said relay, and means responsive to the operation of said relay for simultaneously grounding all of the exposed conductors.

5. Apparatus for the protection of a plurality of exposed conductors comprising a gas-filled rectifier tube, a condenser, a relay having a winding connected in a circuit including said tube and said condenser, said circuit being connected across two of the exposed conductors, and means responsive to the operation of said relay for simultaneously grounding all of the exposed conductors,

6. Apparatus for the protection of a plurality of exposed conductors comprising a condenser, a relay, two gas-filled tubes connected in a circuit including the winding of said relay and said condenser and extending to two of the exposed conductors, a pair of resistors each of which is connected in shunt with one of said tubes, and means responsive to the operation of said relay for simultaneously grounding all of said conductors.

7. In an arrangement for the protection of a plurality of current carrying conductors, the combination of a plurality of protector blocks, a saturating reactor, each block being connected between one terminal of the reactor and one of the various conductors, the other terminal of the reactor being grounded, a relay having two windings one of which is connected to said reactor, a pair of gas-filled tubes connected in series with each other and with the other winding of said relay between two of said conductors, a pair of resistors each of which shunts one of said tubes, and means responsive to the operation of said relay for simultaneously grounding all of said conductors.

LELAND KASSON SWART.

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