US1765497A - Relay - Google Patents

Description

June 24, 1930. c, cfi so 1,765,497

RELAY Filed March 15, 1928 Fig 1. M

Q INVENTOR Charles Morrison.

' ATTORNEY Patented June 24, 1930 UNITED STATES PATENT OFFICE CHARLES MORRISON, OF HAGERSTOWN, MARYLAND, ASSIGNOB T WESTINGHOUSE ELECTRIC 8c MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA RELAY Application filed March 15, 1928. Serial No. 261,816.

My invention relates to electrical protecpive devices and particularly to protective reays.

One object of my invention is to provide a protective relay for sectionalizing a portion of an electrical system when it becomes faulty.

Another object of my inventionis to provide relays for the above purpose having such characteristics that, in a system divided into 10 a plurality of sections by substations and circuit interrupting devices, those relays which are nearest to the faulty section and control the associated interrupters, including the faulty section, will operate and isolate that section.

A further object of my invention is to provide a relay that will automatically vary the time element of its operation in accordance with its distance from the location of the fault.

Relays of the impedance type, at present available and utilized, to a great extent, in protective distribution systems, embody two elements, one of which is current-actuated and voltage-restrained and the other of which is a directional element. The current-actuated element is influenced to develop an actuating or operating force in proportion to the value of the circuit current, but operation of that 0 element is prevented, however, during normal conditions, by a voltage element which is energized in accordance with the circuit voltage. Upon the occurrence of a faulty condition which causes the circuit voltage to diminish to, or below, a predetermined value, the restraining'force of the voltage element is proportionately diminished and the effectiveness of the current element is proportionately increased. Under such conditions, the force developed by the current element may exceed the restraining force developed by the voltage element, and will close a set of contact members associated with the current element.

The directional element is substantially a watt-meter-type relay provided with current and voltage windings on the same magnetizable core to actuate an induction disc in the one or the other direction, depending upon the direction in which the energy traverses the circuit to which the element is connected.

The induction disc is arranged to actuate contact members to effect their engagement in one predetermined direction, or in both directions, depending upon the circuit to be controlled. For the application to be considered herein, the directional element will be utilized to effect engagement of the contact members only when the disc moves in one predetermined direction. When the disc tends to move in the other direction, a back stop will arrest its movement a desired distance from normal neutral position.

The current-actuated element embodies, in addition to the voltage restraining element, a spiral spring through which the induction disc operates to efi'ect closure of the associated contact members. Consequently, when the voltage is normal and the current attains, or even exceeds, the normal value of circuit current, considerable energy may be stored in the spring, although it will continue inefl'ective to close the contact members because of the greater restraining force of the voltage restraining element.

It, while the relay is in a well energized condition, with considerable energy stored in the spring, a fault should occur upon the system which would cause the voltage to diminish, the contacts of that element would be closed.

Because of the substantial amount of energy stored in the spring, and because of the design involving an induction disc, the resetting of the disc by the expenditure of the energy stored in the spring would be relatively slow. In fact, the contacts might be held closed for a couple of seconds before the a restoration of the disc to normal position would re-open them.

If the fault energy was flowing in the direction opposite to that for which the directional element was adjusted, the contact member associated with the directional element would be maintained opened. Under conditions prevailing in some systems, however, Where more than one source of energy is connected to the power system, the disconnection of a faulty section may cause a reversal in the direction in which the energy traverses the adjoining section. If the relay which has just been described should be connected to the adjoining section, the result of the disconnection of the faulty section of the system would be to cause the directional element to immediately reverse its position and close its contact member. Since the directional element is relatively fast in its operation, its contact member might be closed before the contacts of the current-actuated element would have had an opportunit to separate in response to the diminished current-actuating force and the increased voltage restrainin force; that is, the directional element will s ift to move its contact member to circuit-closing position before the current-actuating element can reset itself upon the restoration of normal conditions. Consequently, the two switchin devices of the two elements of the relay will be closed, and, since they are co-operatively connected to trip an associated interrupter, that interrupter will improperly be caused to open its section although that section is in normal condition.

A further object of my invention is to prevent such false operation in relays connected to power systems in which an apparent energy reversal may result upon the disconnection of a faulty section, without impairing the efi'ectiveness of the relay to operate properly when real trouble occurs on its associated' section.

In the accompanying drawings;

Figure 1 is a diagram of a section and a protective relay therefor arranged to operate in accordance with the principles of my invention, and

- Fig. 2 is a single line circuit layout of a representative power system in which relays embodying my invention have particular utility.

In order to prevent false operation of the kind which I have just described, I provide an auxiliary switch in circuit with the switches of the two elements of the relay, and control-the operation of the auxiliary switch in accordance with the current energization of the current-actuated element but so design its responsiveness that it will be relatively quick to open and reset, by providing such a quick-operating switch in the circuit of the switches of both elements of the relay, that the establishment of a tripping circuit by the closure of the directional element of the switch while the current-element switch is still closed, will be precluded.

In Fig. 1, I have illustrated the manner of conneetin the windings of a relay 10 to a portion 0 the power system between two stations or substations 11 and 12. The relay 10 comprises a current-actuated element 13 and a directional element 14. The current element comprises a magnetizable core member 15 which is energized by a current winding 16 to develop a driving flux which influences an induction disc 17 to develop a force to move a pivoted member 18 to control a pair of contacts 19.

A damping magnet 21 is disposed adjacent to the periphery of the induction disc to impose a damping action on the induction disc and to so control it as to cause its angular velocity to be substantially proportional to the value of the current energizing the magnetizable core member 15.

The force developed by the disc 17 is impressed upon the pivoted lever 18 through a spring 22 and, under normal conditions, a substantial amount of energy maybe stored in the spring without effecting the engagement of the contact members 19 because of the restraining action of the restraining voltage coil 23 which holds a magnetizable core 24 against movement when the voltage of the circuit is substantially normal.

Upon the occurrence of a fault in the sysstem sufliciently near to the relay 10 to diminish the voltage impressed upon the winding 23, the restraining efi'ect of the voltage coil 23 is diminished, and the force developed by the induction disc 17 and transmitted through the spring 22 is rendered more effective. changes in the current and voltage, to such an extent that the current actuating force exceeds the voltage restraining force, the contacts 19 will be closed.

The directional element 14 comprises a core member 30 which is provided with a current winding 31 and a voltage winding 32 both of which cooperate to establish a flux to actuate an induction disc 33 in the one or the other direction, depending upon the direction of the energy in the circuit to which the current voltage coils are connected. When the energy flows in one direction in the circuit, the disc will rotate in one direction, which may be predetermined by properly connecting the windings of the relay to the circuit. When 'the energy reverses and flows in the opposite direction in the circuit, the movement of the disc will be reversed and it will be actuated in the ,opposite direction. The disc 33 is arranged to control a switching device to effect engagement of contact member 34 when the disc rotates in a predetermined direction. A stop 35 is provided in order to limit the movement of the disc in the opposite direction, in which no control of contact members is desired or efiected.

In the systems heretofore employed for the protection of power circuits, the contact members 19 and 34 of the current-actuated element and of the directional element, respectively, have been connected in series so that, when fault energy traversed the circuit in a predetermined direction, the contact members would be engaged to close a tripping circuit to an associated circuit interrupter. In order to prevent faulty opera- When the two forces change, due to.

tion that occurred under some conditions, which will be explained in connection with the diagrammatic layout of Fig. 2, I have provided an auxiliary contact-controlling element 36 associated with the current-actuated element 13.

The auxiliary element 36 comprises an auxiliary induction disc. 37 which is subjected to the flux of the core 15. When a in series therewith, to vary the excitation of the windings, and the restraining springs 22 and 38 are also adjustable to permit the adjustment of the relay parts for operation at definite values.

For the purpose of the present invention, the adjustment of the auxiliary element will be such that the contacts 39 will engage slightly before the contacts 19. Since no considerable amount of energy will be stored in the spring 38, whereas, such energy will be stored in the spring 22, the resetting of the auxiliary element, or, in other words, the separation of the contact members 39 will be efiected much faster than the separation of the contact members 19. It is the quick separating action or resetting action of the auxiliary element which I utilize to open the tripping circuit of the relay, under certain conditions, to prevent false operation.

Upon referrin to Fig. 2, the reason for the necessity o the auxiliary protective feature will become apparent. The system shown in that figure consists of generating stations 40 and 41 and substations 42, 43 and 44. The generating stations and the substations are connected by several lines which are indicated by the numerals 45 to 50, 'inelusive.

Let it be assumed that the relay is disposed at the position 52 adjacent the interrupter at generating station 41 in line 48.

The directional element of the relay at point 52 will be so connected that it will effect engagement of its contact members 34 only when energy flows away from the bus;

that is, from the generating station 41 to the substation 43. When energy flows from the substation 43 tothe bus of the generation station 41, the contact members 34 of the "directional element will be held separated.

The operation of the current-actuated element, however, will be the same, irrespective of the direction of energy flow in line 48. The function of the directional element in the relay v10 is, therefore, to determine when the current-actuated element may be rendered effective to control its associated in terrupter.

For the sake if simplicity, the complete connections from the relay devices to the associated interrupters are not shown since they are substantially the same as those illustrated in Fig. 1.

Let it be assumed that a fault now occurs upon the line 49 between the generating station 41 and the substation 44. Fault energy will flow from the generating station 40, through the line 50, through the bus at station 44 into line 49. The protective relays at the substation end of line 49 will be set to operate the interrupter upon the occurrence of a fault in line 49, and, consequently, will operate very soon after the occurrence of a fault and will disconnect the line 49 from the substation 44. The generating station 40 will also feed energy to the faulty section 49 through lines 45 and 46 and substation 42, and line 47 and thence through substation 43, through line 48 and the bus of the generation station 41. The relays at the generating-station end of line 49 will also operate to clear the line 49 practically at the same time as the relays at the substation 44.

However, the relay at the point 52 in the line 48 adjacent the generating station 41 will have been sufiiciently energized to close the contacts 19 of the current actuating element although the contacts 34 of the directional element are held open.

Immediately upon the disconnection of the faulty line 49 at the generating station 41, the energy flow from the generating station 41 into the system through the line 48 causes the directional element 14 to immediately reverse and thereby effect closure of its contacts 34. Such reversal and closure of the contacts will be effected very quickly and before the contacts 19 of the current-actuated element may restore itself to normal position with the re-establishment of the voltage on the system.

If the contacts 39 of the auxiliary element were not present, the circuit between the contacts 19 and 34 would be completed, and the associated interrupter at the generating station end of line 48 would be tripped open and tion of a faulty section may cause a reversal in the energy flow and tend to establish a false condition of operation in certain associated relays.

For the sake of simplicity, I have illustrated an embodiment of my invention in which the auxiliary, element is disposed to cooperate with the current-actuated element already available. It will be obvious to those skilled in the art, however, that separate and independent auxiliary elements may be employed to provide the same protective feature. My invention, therefore, isnot limited to the specific arrangement that is illustrated, but may be variously modified without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. The combination with a protective relay embodying a current-actuated induction-disc element normally restrained in its operation, a directional induction disc element, and two switching devices respectively controlled by the two, elements to cooperate to control an external circuit upon the occurrence of abnormal conditions in that circuit, of an auxiliary switching device cooperatively related to the other switching devices and means associated with the current-actuating element for controlling the auxiliary switching device to disturb the cooperative relationship between the other two switching devices u on the occurrence of conditions resulting a ter the actuation of the current-actuated switch to its effective position but before that switch canleave such position in response to those conditions.

2. A relay for an electric system comprising a current-actuated voltage-restrained induction-disc element relatively slow to reset after operation, and an energy directional element relatively quick in operation and in resetting, a switch device associated with, and controlled by, each element, and an auxiliary 'switchfor cooperatively associating said switch devices when energy flows in a predetermined direction in the system but for precludin such cooperative association if the energy ow is in such direction because of a quick reversal while the current-actuated v switch is closed and before it can reopen.

3. In combination with an electric circuit having a circuit mterrupter therein, of a control means therefor including a pair of re-v lays responsive to predetermined circuit conlays responsive to predetermined circuit conditions, one of said relays having a slow-resetting characteristic with respect to the other, and means for rendering said control means-ineffective until both relays have reset afteran actuation. 1

4. In'combination with an electric circuit having a circuit interrupter therein, of a control means therefor including a pairof reditions, one of said, relays having a slow-resetting characteristic with respect to the other, and means for renderin said control means ineffective until both re ays have reset after an actuation, said means including a quick-acting switching device responsive to the magnitude of the current traversing said circuit.

5. In combination with .an electric circuit having a circuit interrupter therein, of a control means therefor including a pair of relays responsive to predetermined circuit conditions, one of said relays having a. slow-resetting characteristic with respect to the other, and means for rendering said control means inefl'ective' until both relays have reset after an actuation, said means including a switching device operatively associated with the operating element of one of said relays.

6. In combination with a circuit interrupter for an electric circuit having a tri circuit therefor, ofmeans for controlling t e completion of said trip-circuit comprlsing two relays having the contacts thereof connected in series in said tri circuit one of said relays having a delaye -resetting characteristic; a third pair of contacts in series in said trip circuit and operating means therefor comprising a substantially instantaneous element operatively associated with one of said relays for operation in accordance with the magnitude of the driving flux thereof.

7; In combination with a protective relay embodying an actuating winding, an induction-disc armature operatively associated therewith, and restraining means for said armature rendering it slow to reset after an actuation, of a second induction-disc arma- CHARLES MORRISON.

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