US1701353A - Protective apparatus - Google Patents

Description

Feb. 5, 1929.

J. BIERMANNS PROTECTIVE APPARATUS Filed NOV. 30, 1927 2 Sheets-Sheet 1 Fig. l.

Inventor: Josef ESLermanns.

HLs Attorney.

N .N W KM M m P O m U N l C m 4 QPM r J. BIERMANNS PROTECTIVE APPARATUS Filed Nov. 50, 1927 2 Sheets-Sheet 2 Inventor: J05 e1 Bievmann s,

by W% His ACCovney Patented Feb. 5, 1929.. g

v 1,701,353 PATENT oFF cE.

JOSEF IBIERHANNS, OF KARLSHORST, NEAR BERLIN, GERMANY, ASSIGNOR TO GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE A?PARATUS.

Application filed November 30, 1927, Serial No. 236,838, and in Germany December 31, 1926.

My invention relates to improvements in protective apparatus for electric systems and more particularly to improvements in pro tective apparatus of the type wherein selectivity is dependent on the distance between the protective apparatus and the fault. An object of my invention is to provide improved protective apparatus whereby to obtain a high degree of selectivity and yet quickly to effect the disconnection of a faulty portion of an electric circuit.

My invention will be better understood from the following description when considered in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the accompanying drawings, Fig. 1 illustrates, partly in diagram and partly in perspective, protective apparatus embodying my invention; Figs. 2 to 5 inclusive are diagrams explanatory of my invention; and Figs. 6 and 7 represent diagrammatically modifications of my invention.

l'n relays of the so-called distance type, the time of operation is dependent on the distancebetween the relay and the fault. If a fault such as a short-circuit occurs near the relay, then it will operate in a very short time which may be called the minimum or fundamental time. The farther the fault is from the relay, the greater the time of operation. As shown in Fig. 2, this time may be for example, substantially in accordance with the straight line ON which represents the de pendence on the position of the fault of the time of operation of the relay Ra located in the station a. The relay Ra normally has only the line section at to protect and the relay "R5 at the station 2') is relied upon to protect the section. be. In case of a shortcircuit n ar station 5, the time of operation of the relay Ra is considerably greater than the minimum time. In such cases damage to the system loaded with the excess current may occur under certain circumstances.

Now, instead of having the time of operation of the relay increase with the distance between the relay and the fault for the section to be protected by the relay, a relay whose time oi operation is substantially constant for faults anywhere on the protected section and increases only for faults outside of the section would satisfy requirements as to selectivity. The characteristic of such a relay he would be substantially as shown in Fig.

8 in which OM is horizontal from station a to station 7) and MN from station 6 to station a has a slope similar to ON of Fig. 1. Since,

however, the time of operation of the relay Ra in case of a short circuit near station 6 in the line section would be only slightly greater than the minimum time of the relay Rb which is to be chosen as great as the minimum time of the relay Ra, the time difference is not sufiicient and both relays may operate thus effecting the disconnection of not only the faulty section but also a sound section. Thisrdisadvantage may be overcome by a relay having the characteristic "OM'N shown in Fig. 4. In this case, the constant time of operation ceases at the point M which must be far enou h from the station 5 to insure the necessary time difference. Also the relay may have the characteristic shown in Fig. 5. In this case, the minimum time is maintained throughout the-section at but for faults outside this section the time of operation increases suddenly from ()M to NN.

In the embodiment of my invention shown in Fig. 1, an electric circuit 10 is arranged to be controlled by suitable interrupting means such as a circuit breaker 11 which is arranged to be controlled by relay means Ra of the socalled distance type. The particular relay means chosen for the illustration of my invention is a modification of the relay disclosed in my United States Letters Patent 1,527,623 issued February 24, 1925, to the assignee of this invention. This relay comprises two independent relatively movable cooperating members suchas contacts 12, 13 which, as shown, are arranged to control the circuit or" the circuit breaker trip coil 9.

On the occurrence of a fault on the circuit 10, the contact 12 is arranged to be rotated against the bias of a spring 14: in the direction indicated by the arrow 15 at a speed dependent on the circuit current through suitable electromagnetic means comprising an induction disc 16 and magnetic elements 17 and 18, the latter of which is provided with windings 19, 20 connected to be energized in accordance with the circuit current through a current transformer 21. On the occurrence of a fault on the circuit 10 with a predetermined direction of power, the contact 13 is arranged to be rotated against the bias of a spring 22 in the direction indicated by the arrow 23 to a position dependent on all a voltage of the circuit 10 through suitable electromagnetic means comprising an induction disc 24 and magnetic elements 25 and 26, the latter of which is provided with windings 27, 28 respectively connected to be energized in accordance with the circuit current and a circuit voltage through the current and potential transformers 21 and 29 respectively. Patent 1,527,623 the magnetic element 26 has its central leg, which carries the current winding 27, arran ed to saturate at the minimum overcurrent or which operationis desired. Consequently,'while the direction of movement of the disc 24 is dependent on the direction of power, the ma itude of the torque exerted on the disc 24- y the windings 27 and 28 is such as move the disc at a speed dependent and therefore to in' accordance with the circuitvoltage. When the direction of power issuch as to move the disc 24 oppositely to the direction indicated by the arrow 23, the voltage contact 13 moves a stop 30 into the path of movement of the contact 12 thus preventing contact engagement. When the direction of power is such as to move the disc 24 in the direction indicated by the arrow 23, the voltage contact 13 will take a position to which it will be followed by the current contact 12 and overtaken in a time dependent on the distance between the relay and the fault.

In Fig. 1, the positions of the parts are those normally occupied, the electromagnets exerting no torques on the discs 16, 24 since their windings 20, 28 are normally open-circuited and become energized only on the ocfrom stationa, were dependent only currence of a current suflicientto attract the magnetic element 17 to close its contacts 31 an 32. Incase of a short-circuit in the immediate vicinity of the relay, the voltage completely disappears and consequently the disc 24 \does not move. Therefore the time required by the contact 12 to overtake the contact 13 isthe minimum time of operation of-the relay. If the increasing voltage which occurs at the relay location with increase in the distance of the fault that is as the faults occur in the section ab farther and farther on the distance between the relay and e fault point, then it would be necessary only to give the spring 22 aconstant reliminary tension corresponding to the vo tage drop from a to M so that all faults between these points will bedisconnected in the minimum time.

However, inasmuch as the voltage drop is dependenent on the value of the short-circult current, I propose in accordance with my invention to influence the-voltage contact-13 by an effect dependent on the difiercnce between the'voltage and the current. This may be done, as shown in Fig. 1, by making the counter to ac, that is the. torq spring 22, etermining the position of; the

As pointed out in my Letters osition the same no of the l disc 24 dependent upon the circuit current. For this purpose the outer end. of the spring 22 is not secured to a fixed point but to a point whose position is varied in accordance with the intensity of the current. As shown in Fi 1, this is done by securing the outer end 0 the spring 22 to one end 0 a lever 33 pivoted at 34.- The other end of the lever 33 is connected to the armature of an electromagnet 35 which is arranged to be energized in accordance with the circuit current so as to increase the tension on the spring 22 as the armature is pulled into its winding against the action of a spring 36 whose tension may be adjusted in any suitable manner. I A. predetermined position of the armature of the electromagnet 35 corresponds to some value of current for which the spring. 22 has a predetermined preliminarytension. The point M may, therefore, be shifted as desired The other end of the spring 22 is not fixed to the disc 24 but in the normalor'rest position of the disc abuts a fixed stop 37 from which it is moved through the rojection 38 on the disc shaft only whenthe disc moves in the direction indicated by the arrow 23. The disc 24 in its rest position is, therefore, not under the influence of the s ring 22 and can turn'freely in the opposite irection to actuig. 6, a voltage drop produced by a current proportional to the circuit current and flowing through a resistance 39 in circuit with the current transformer 21 can be so arranged as to oppose the effect of the voltage in the winding 28. A sprin 22' provides the necessary counter torque or thedisc 24. In this Fig.6 only that'portion of the relay Ra whose structure is altered is'shown. It will be understood that the remainder of the structure can be according to Fig. 1. i

In order to'obtai the step arrangement characteristic shown in Fig. 5, I rovide as shown in Fig. 7 in conjunctlon wit the relay Ra of which only the voltage element is shown for simplicity, a relay 40 which is'oper- 'ative on the occurrence of a fault in a predetermined portion of'the circuit such as a section be to the right of section ab to eliminate the effect of the current inthe actuating means of the voltage contact. While any suitable relay may be employed,I- have chosen for illustration a role of the'directional dis tance type such as disclosed in the copending. application of'Otto Mayr for circuit protection, Serial No. 92,093, filed March 3, 1926, and assigned to the same assignee as this invention. As shown this relay is of the inducmorass tion disc type having a disc 41 and electrornagnetic actuating means therefor comprislug windings 42, 43, 44 which are connected and arranged to exert an effect proportional to a voltage of the circuit and the difierence between the circuit current and a current roportional to a potential of the circuit an inversely proportional toa characteristic of the impedance of a portion of the circuit such as the section ab. The Winding 42 is connected to be energized in accordance with a potential of the circuit and cooperates with the windings 43 and 44 which work in opposition. The winding 43 is connected to be energized in accordance with the circuit current and the winding 44 is connected in series w th an impedance device 45 across the secondary of the potential transformer 29. This impedonce device is proportioned to have an impedance characteristic proportional to an impedance characteristic of the section at. The operation of this relay is such that for a fault outside of the section at, the disc 41 will be moved in one direction and for a fault in the section at in the opposite direction. Then under normal conditions and for a fault on the section the relay 49 will maintain its contacts 46 closed and the circuit of the electrornagnet 35 of the relay Ra energized. If, however, a fault occurs outside the section at as for example in the section be to the ri ht, the torque on the disc 41 will reverse t us opening the contacts 46 and removing the control of the electromagnet 35 from. the voltage contact 18 of the relay Ra. The spring 36 then holds the lever 33 against a stop 47 which may be adj ustablc. There will then be a definite tension in the spring 22 such that for faults to the right of the station b, the time characteristic will be as indicated by NN in While shown and described my in= vention in considerable detail, I do not desire to be limited to the exact arrangements shown, hut seelr. to cover in the appended claims those modifications that fall withthe time, spirit and scope of my invention.

What ll claim as new and desire to secure by Letters Patent of the United States, is:

l... electric circuit protective relay in cluding two independent relatively movable cooperating members. means for actuating one member in accordance with the current of the circuit, means for biasing the other member against movement in one direction, and electromagnetic means for actuating said other member in said direction connected and arranged to operate in accordange with the difference between a voltage of the circuit and the circuit current.

2. An electric circuit protective relay including two independent relatively movable cooperating contacts, means for actuating one contact in accordance with the current of the circuit, means for biasing the other contact against movement in one direction, and means for actuating said other contact in said direction in accordance with the difference between a voltage of the circuit and the current of the circuit.

3. An electric circuit protective relay including two independent relatively movable cooperating members, means for actuating one member in accordance with the. current of the circuit,'means for biasing the other member against movement in one direction, and means responsive to the current and volt-, age of the circuit operative with power flow to actuate said other member in said one direction in accordance with the difference between a voltage of the circuit-and the circuit current. c

4-. An electric circuit protective relay including two independent relatively rotatable cooperating members, means for rotating one member in accordance with the current of the circuit, means for biasing the other member against rotation in one direction; and roeans for rotating the other memher in said direction comprising electromagnetic means arranged to exert a torque dependent on the difference between a voltage of the circuit and the current of the circuit.

5. An electric circuit protective in.- cluding two inde endeut relatively movable cooperating more ers, means for actuating one member in accordance with current of the circuit, means for biasing other member against movement in one direction, means for actuating said other member 111 said direction in accordance with difierence between a voltage of the circuit and the current of the circuit, and relay means open ative on the occurrence of a fault in a prede termincd portion of the circuit to eliminate the effect ot the current the actuating means of said other member.

a. in combination with tin-electric circuit and circuit interru ting means for one end of a section of the circuit, means for controlling said interrupting means including a re lay having two relatively movable cooperating members, means for moving one member in accordance with the current of the circuit and means for movin the other member in accordance with the di erence between 9. voltin the circuit in a predetermined direction age of the circuit and the circuit current, and

means operative on the occurrence of a fault.

outside of said section to eliminate the efiect of the current in the actuating means of said other member.

,7. In combination with an electric circuit and circuit interrupting means for one end of a section or the circuit, means for controllmg said interrupting means including a relay having two relatively movable cooperating members, means operative on the occurrence of an over-current condition to move one member in accordance with the current,

means for biasing the other member against means operative on the occurrence of a fault movement in one direction, and means inoutside of said section to eliminate the efiect eluding a distance relay operative on the 00- of the current in the actuating means of said currence of an over-eurrenteonditi0n for acother member. I

5 tuating said other member in said direction In witness whereof, I have hereunto set my in accordance with the difference between a hand this 28th day ofNovember, 1927. v voltage of thejcircuit and the current, and .OSEF BIERMANNS.

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