US1204509A - Electrical relay. - Google Patents

Description

B. H. SMITH.

ELECTRICAL RELAY.

APPHCATION FILED JULY 11.1914.

1,204,509. Patented Nov. 14, 1916.

UNITED STATES PATENT OFFICE.

BENJAMIN H. SMITH, OF TURTLE GREEK, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

ELECTRICAL RELAY.

Specification of Letters Patent.

Patented Nov. 14, 1916.

To all whom it may concern: y

Be it known that I, BENJAMIN H. SMITH, a citizen of the United States, and a resident of Turtle Creek, in the county of Allegheny and State of Pennsylvania, have invented a new and useful. Improvement in Electrical Relays, of which the following is a specification.

My invention relates to electrical protective devices and particularly to relay mechanisms and systems that are employed for tripping circuit breakers, or operating other devices, upon the occurrence of predetermined circuit conditions.

The object of my invention is to provide a simple and economical relay mechanism of the character indicated that may be operated by current derived from the line or circuit in connection with which the circuit breaker or other device is employed, thereby obviating the necessity of employing a separate source of power for supplying the operating current, and the contact members of which shall not be subjected to injurious arcing, or to the possibility of welding or sticking together, or of becoming burned so that they will not conduct current.

Considerable diiiiculty has heretofore been experienced with relay mechanisms for circuit breakers and similar devices, that are employed 'in connection with alternating current circuits, when it has been attempted to derive "the current for tripping or operating the breakers from the said circuits. This dificulty has been due to the fact that the current for operating the relay mechanism and'tripping the circuit breakers has usually been derived from the main circuit by means of a series transformer, the secondary circuit of which includes the operating coil of the relay, the tripping coil of the circuit breakers, and the relay contact members which normally short circuit the latter coil, but are separated to permit its energization upon the occurrence of an overload or other predetermined circuit condition. Thereis usually a sufiicient amount of current in this secondary circuit to cause arcing at the relay contact members, "and at times it may be sufiicient to cause them to weld or stick together, and the difliculty is rendered more serious when there is slow separation of the contact members due to the employment of a dash pot, or other retarding device, for introducing a time interval between the occurrence of an overload and the opening of the circuit breakers. Furthermore, arcing between the contact members may so burn and injure them as to prevent them from making good electrical contact when brought into engagement.

According to the present invention, I have provided a tripping device that is supplied with energy from the main circuit, but that does not require the interruption of a circuit carrying an appreciable current, thereby overcoming the hereinbefore mentioned difliculties.

In another application, Serial No. 850,331, filed of even date herewith, I have disclosed an electromagnetic tripping device for circuit breakers and similar apparatus that involves only the addition of a small core part and two coils to the parts of present standard relay devices. In the present instance, I have provided a completely new structure for the electromagnetic tripping device to accomplish the same results as are accomplished by the device of the aforesaid ap plication.

The single figure of the accompanying drawing is a diagrammatic view of a part of a system embodying my invention.

A typical system in connection with which the present invention may be employed comprises an alternating current circuit 1 that is adapted to be interrupted by means of a circuit breaker 2 and in series with one conductor of which is the primary winding 3 of a current transformer 4, the circuit of the secondary winding 5 of which includes the circuit 1, or of any other desired abnormal circuit condition. This relay may be arranged to close the switch 8 instantaneously, or after a time interval, as desired.

The circuit breaker is adapted to be tripped by means of an electromagnetic relay or tripping device that comprises a pivotally mounted armature 10 and two magnetizable core parts 11 and 12 that are arranged substantially in the form of a hollow rectangle with spaces or air gaps 13 and 14 between their opposing or abutting faces.

' of the armature 10 is then drawn to the The lower end of the armature 10 extends into the air gap 14, but is not of suflicient width to entirely close or bridge the gap. In fact, the width of the air ga 14 is greater than the combined widths o the armature 10 and air gap 13, so that normally the air gap between the right side of the armature 10 and the adjacent pole face of the core part 11 is greater than the width of the air gap 13. A spring 15 serves to normally maintain the lower end of the armature 10 in engagement with, or closely adjacent to, the pole" face of the core part 12.

The armature 10 is surrounded by a coil 16 that receives current from the secondary winding 5 of. the series transformer, the internal diameter of-the coil being such as to permit of movement of the armature between the opposing pole faces of the core parts 11 and 12. The part 12 is surrounded by coil 17 v the circuit of which is normally open but is adapted to be closed or short circuited by the switch 8 of the relay 7. I

The core parts 11 and 12 provide a divided magnetic circuit .for flux set up in the armature by the coil 16. Inasmuch as the spring 15 maintains the lower end of the armature 10 closely adjacent to the lower end of the core partzl2, the reater portion of the flux will traverse the livision of the magnetic circuit provided largely by the core part 12, because the air gap 13 is shorter than the air gap 14, andthe reluctance of the said division of the magnetic circuit is less than that of the other division. This condition will prevail'so long as the load upon the circuit 1 and the other electrical conditions thereof are normal. However, upon the occurrence of an overload upon the circuit 1, orof some other abnormal condition, the relay 7 will close the switch 8 and thereby establish a short circuit for the coil 17.

The short circuiting of the coil 17 causes the effective reluctance of the division of the magnetic circuit includin the core art 12,

to be very materially increased, thereby causing the greater portion of the flux produced by the current in the coil 16 to. traverse the division of the magnetic circuit provided by the core part 11. The lower end right, and the tripping mechanism of the the flux traversing the armature, one of able armature and two magnetic paths for the flux traversing the armature, one of which includes a substantially constant air gap and the other of which includes a variable air gap, a main winding surrounding the armature, and an auxiliary winding for the magnetic path that includes the constant air gap, the circuit of the auxiliary winding being controlled by the said relay.

3. An electromagnet comprising a magnetizable core having a movable armature and a divided magnetic circuit presenting poles upon opposite sides of the armature, one of said divisions including an air gap, a main winding for the armature, and an auxiliary winding for the core division that does not include the air gap.

4. An electromagnet comprising a magnetizable core having a movable armature and a divided magnetic circuit presenting poles upon opposite sides of the armature,

one of said divisions including an air gap, a normally energized winding for the armature, and a normally denergized winding for the core division that does not include the air gap.

5. An electromagnet comprising a magnetizable core having two air gaps of unequal width, an armature extending into the wider air gap and dividing the core into two magnetic circuits one of which includes the narrower air gap, a main winding for the armature, and an auxiliary winding for the core division that includes the narrower air gap.

6. An electromagnet comprising a magnetizable core having two air gaps of unequal width, an armature extending -into the wider air gap and dividin the core into two magnetic circuits'one 0 which includes the narrower air gap, anormally energized main winding surrounding the armature, and a normally deenergized auxiliary winding for the core division that includes the relatively narrower air gap.

7 The combination with an electrical circuit and a relay, of an electromagnet comprising a magnetizable core having a movablearmature and two magnetic paths for the flux traversing the armature one of which normally has greater reluctance than the other, and a winding for the path of lesser reluctance that is controlled by the relay for increasing the effective reluctance of the path of normally lesser reluctance under predetermined conditions.

8. An electromagnet comprising a magnetizable core having a movable armature and two magnetic paths for the flux traversing the armature, one of which includes an air gap, a main Winding surrounding the armature, and an auxiliary Winding :tor the path that does not include the air gap.

9. An electromagnet comprising a magnetizable core having a movable armature and two magnetic paths for the flux traversing the armature, one of which includes an air gap, a main winding for the armature, and an auxiliary Winding for the path that does not include the air gap.

10. An electromagnet comprising a magnetizable core having a movable armature and two magnetic paths for the flux traversing the armature, one of which includes a substantially constant air gap irrespective of the movement of the armature, a main winding surroundin the armature, and an auxiliary Winding tor the path that does not include the air ga 11. An electromagnet comprising a magnetizahle core having a movable armature and two magnetic paths for the flux traversing the armature, one of which includes an air gap, a normally energized main Winding surrounding the armature, and normally deenergized auxiliary windings for the magnetic path that does not include the air gap.

12. The combination With an electrical circuit and a relay, of an electromagnet comprising a magnetizable core having a movable armature and two magnetic paths for the flux traversing the armature one of which normally has greater reluctance than the other, a Winding for the armature, and

a winding for the path of lesser reluctance that is adapted to he short-circuited by the relay for increasing the efiective reluctance of the path of normally lesser reluctance under predetermined conditions.

13. An electromagnet comprising a mag netizable core having a movalole armature and two magnetic paths for the flux that traverses the armature, one of which includes a constant air gap and the other of which includes a variable air gap, and a Winding for the magnetic path that includes the constant air gap.

M. An electromagnet comprising a magnetizahle core having a movable armature and two magnetic paths for the Hun that traverses the armature, one path of which normally includes an air gap, and means for increasing the effective reluctance of the path that does not normally include the air gap. v

15. An electromagnet comprising a magnetizable core having a movable armature and two magnetic paths for the flux traversing the armature, one of which includes an air gap, a normally energized main Winding surrounding the armature, and an auxiliary Winding for the magnetic path that does not include the air gap, said auxiliary Winding being adapted to be short circuited under predetermined conditions.

in testimony whereof, I have hereunto subscribed my name this 80th day of une,

BENJAMIN H. SMITH. Witnemes:

PAUL MAcGAr-ran,

B. Hines.

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