US1374727A - Protective device - Google Patents

Description

H. G. FRENCH.

PROTECTIVE DEVICE.

APPLICATION FILED OCT. 25. 1919.

1,374,727. Patented Apr. 12, 1921.

TIME

I Invehtor: Henry G.Fr-ench,

a I Hrs Attorney UNITED-STATES PATENT OFFICE.

HENRY G. FRENCH,

OF SCHENECTADY, NEW YORK, ASSIGNOR 'IO GENERAL'EEECTRIC.

COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE DEVICE.

Specification of Letters Patent.

Application filed October 25, 1919. Serial No. 333,248.

to provide a relay of the induction type which is operative in response to a predetermined abnormal condition in a positive and definite manner, which will move positively to contact controlling position and which embodies other features to be described more in detail hereinafter.

In relays of the induction type in which a rotatable armature is controlled by torque and counter-torque elements, it is necessary to compensate for the increase in eflect of the counter-torque element when the armature is actuated by the torque element. Without compensation a current just enough to start the armature rotating is insuflicient to carry the armature positively to complete its path of movement as the armature will float or move to aposition where the effects of the torque and counter-torque elements balance. Again the pick-up value of current for which the relay is set to operate may not positively start the armature rotating due to the small increase in torque over the counter torque.

According to my invention, I overcome these disadvantages by providing a relay which has a positive and definite pick-up when the current reaches a predetermined value and which is carried positively and definitely to complete its path of movement on that value of current or that driving torque sufficient to initially start the armature in rotation.

The novel features which I believe to be characteristic of my invention will be definitely indicated in the claims appended hereto while the features of construction and mode of operation will be understood by reference to the following description taken in connection with the accompanying drawing-in which:

Figure 1 shows, in perspective, a relay embodying my invention; Fig. 2 shows, in perspective, a relay embodying a modified form of my invention, and Fig. 3 is a graphic, illustration of the operating characteristics of my improved relay.

In Fig. 1 the relay of my invention comprises a rotatable armature member 1, carried by a shaft 2, which carries a movable contact 3 adapted to be moved into and out of engagement with cooperating fiired contacts 4 by rotation of the armature, to control an auxiliary circuit. This circuit may operate a trip coil or auxiliary relayto open the circuit protected by the relay of my 1nvention. The rotatable armature 1 is actuated and controlled by a torque-producing element 5 tending to drive or rotate the armature 1 in contact-closing direction, and also by a counter-torque or restraining element 6 producing an opposing or counter torque tending to rotate the armature 1 in the opposite direction. Normally the effect of the counter-torque element 6 predominates to hold the armature against a stop 7.

The torque-producing element 5 is preferably of the electromagnetic type consisting, as shown, of a U-shaped magnetic member 8 upon which is mounted actuating windings 9 connected in series. Upon the pole'tips of the magnetic member 8, between which the armature is movable, are shading coils 10 to provide a rotative effect on the armature. The counter-torque element 6 is also preferably of the electromagnetic type comprising a U-shaped magnetic member 11 with actuating windings 12 connected in series and in a series circuit with windings 9 of the torque'element 5. The element 6 is mounted at the opposite side of the armature 1. from the torque element 5 and is provided with pole tips between which the armature is movable. These pole tips are provided with shading coils 13 which are relatively movable by an adjusting means 14 to vary the counter torque as desired.

The counter-torque element 6 is also provided; with a positive pick-up device consisting of means for automatically short circuiting the flux across the pole tips and hence the flux cutting the rotatable 'armas ture. This means consistsof leakage poles 15 having an air gap substantially greaterthan the gap between the pole tips. This gap is adapted to be bridged to form a shunt path for the flux in response to prethus weaken the For determined conditions and effect ofthe counter-torque element.

Patented Apr. 12, 1921.

enabling the leakage poles to. form a shunt path, provide a plunger 16 extending through the lower leakage pole l5 and ad- 5 and 6am connected in series in the secondary circuit of a transformer 19, the primary or which is responsive to the current on the line 20 to be protected. Y

The operation of my relay may be described as follows: normally the current in windings 9 and 12 is such that a small flux is created in magnetic members 8 and 11, creating opposing torques on the'armature 1. The effect of the counter-torque element 6 normally predominates -to hold the armature against stop 7. When the current in conductor 20 reaches a predetermined amount, a proportional current flows through windings 9 and 12 increasing the flux in members 8 and 11, and hence the torque and, counter torque exerted by elements v5 and 6' respectively. The flux in counter-torque element 6' upon this'predetermined value of current, for which the device is set to operate, is sufiicient to operate the pick-up device attracting plunger 16 and movingit into engagement with upper leakage pole 15. The plunger thus bridges the leakage poles and forms a path for I 'the flux in shunt to that across the pole tips of element 6. The result of the attractlon of the plunger 16 is to instantly short circuit the flux creating the counter torque on armature 1 reducing thereby the eflect of the counter-torque element. The driving element 5 thereupon overcomes the counter-torque element and positively moves the armature 1 to complete its path of movement and bring contacts 3 and 4 into engagement.

\ The engagement of conta cts 3 and 4: functions to enable the circuit 20 to be opened. A comparatively light spring 21 is connected to the shaft 2 adapted to be tensioned by the movement of the armature 1 and which operates to return'the armature to its initial position when current to the control elements 5 and 6 is interrupted; It is thus apparentithat as soon as the current and hence the flux in the countertorque element 6 reachesa'predetermilied amount, the pick-up device automatically operates with a positive action to reduce the effect of the counter-torque element and enable the torque element 5 to effectively predominate and move the armature ldefinitely' and positively intocontact closing position.- All danger of floating is thereby definitely eliminated. The pick-up value and hence the point of operation of the relay may be controlled by adjusting the air gap between the leakage poles which is accomplished by adjusting the position ofthe plunger. The armature 1 may be provided with a drag element, such as a permanent magn'et of well known construction, ifsuch is desired, for giving a time lnterval in the operation of the relay. I have not shown such an element in Fig. l for purposes of clearness.

In Fig. 2'I have shown/a modified form of my invention in which the rotatable armature member 1 is controlled by a torque element 5 and a restraining or countertorque element. In this case the countertorque element 'comprises the spring 21. The movement of armature 1 is delayed by the permanent drag magnet 22. The driving or torque element 5 is of the' electromagnetic type having a laminated magnetic member 23 upon whlch is Wound the. actuating winding 24. controlled from the circuit to be protected. The armature 1 is rotatable between the polev tips of the magnetic member 23 which are provided with hence the size of the air gap may be varied by adjusting means 26 to close the magnetic circuit of member 25 under any predetermined value of flux or current in winding 24. In the arrangement shown', I provide of the magnetic member 23 movably positioned and extending through the lower portion 27 of the member. The plunger is surrpunded by a suitable casing 28.

Normally the effect of counter-torque elerment 21 predominates to hold the armature against the stop 7. Dueto the reluctance of the magnetic current of member 23, little flux passes the pole tips and little driving torque is exerted on the armature 1. Upon increase in current in winding 24, the flux in member 23 increases until it is sufiicient to attract plunger 25- which moves to close the air gap in the circuit of member 23 there by greatly increasing the flux in member 23. The adjustable plunger 25 serves as a pickup device to greatly increase the torque exerted by the driving element 5, upon that value of current for which'the device is set to operate. When the pick-up value of. current-is reached, the torque exerted by the ,the movable core or plunger 25 as one leg I element 5 positively overcomes the spring or counter-torque element 21 and moves the armature positively and definitely in contact-controlling direction until contacts 3 and 4 are brought into engagement. Upon the opening of the circuit to be protected,

pose a thin brass washer may be used on the plunger or an other similar de ice.

In *Fig. 3 have .shown in a graphical manner the time current curve of the relay embodying the principles of my invention. Depending on the setting of the pick-up device, which is noted by the vertical line aa, the relay is held inoperative until the I pick-up value of current 1s reached. ,Upon

the occurrence of the pick-up value of current, the relay is positively set into operation and completes its operation definitely and with a positive action. The effect of the pick-up device is, therefore, to eliminate that portion of the time current curve at the left ofthe line aia, shown in dotted lines, and only that portion ofthe curve is obtained which is shown in a solid line. In this manner the selective action of relays of this type are dependable and the relays are positive in action. I

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

1. In a relay of the induction type, the. combination with a rotatable armature, a torque-producing element for moving said armature in response to currents above a predetermined amount, an element producing a counter torque normally overcoming said torque element, 'andadjustable means responsive to currents of any predetermined amount for varyingthe pick-up point of said torque-producing element.

2. A relay device comprising a rotatable armature, contacts controlled thereby, a motor element tending to rotate said armature in" contact-controllin direction, a restraining element normal y rendering said motor element inefiective, and means adjustable to operate in response to any predetermined value of current for causing said motor. element to'positively overcome said restraining element and carry said armature through its complete path of travel into contact-controlling position.

3.111 an induction relay, the combination with a rotatablearmature, contacts closed'thereby, an electromagnetic element operative in response to current above apredetermined amount to tureto contact-closing position, restraining means normally overcoming the effect of said element, and means adjustable to cause said electromagnetic element to overcome said restraining element and move said'70 armature into contact-closing position at any predetermined point in the time current curve of said relay.

4. In a relay device, a rotatable armature, thereby, tating said contacts in contact-controlling direction, a restraining element normally overcoming said torque element, and means the combination with adjustable to operate in'response to abnormal conditions in excess of any redetermined amount for causin said torque-producing element to quic y and. positively overcome said restraining element and move said armature into contact-controlling position.

5. In a relay device of the induction type, the combination with a. rotatable armature. contacts controlled thereby, a motor element producing a torque direction to rotate ,the' same in contactcontrolling position, an electromagnetic element having a magnetic flux adapted to produce a counter torque on said armature,

means responsive to currents above any predetermined amount for reducing the flux of said counter-torque element tending to efi'ect said armature whereby said motor element predominates to quickly rotate said armature into contact-controlling position.

6. In a relay of the induction type, the combination with a rotatable armature, an electromagnetic element producing a flux tending to rotate said armature in one direction, a producing a flux tending to rotate said armature in the opposite direction but inefiec= tive until the current exceeds a predetermined amount, means associated with said first mentioned element operative upon currents above said predetermined amount to short circuit the flux thereof to permit said armature to move quickly under the influence of said second element.

7. In a relay device, a rotatable armature, contacts controlled thereby, a torque-producing element for rotating said armature into contact-oontroL ling position, an electromagnetic element producing a counter torque on said armature normally overcoming said torque element, main poles for said counter torque element between which said armature is movable,

secondary poles for said counter-torque element outside the and means whereby the normal path of the flux of said counter-torque element is through said main poles but upon the ocrotate said arma- 65 contacts controlled 75 a torque-producing element for roon said armature in a 90 second electromagnetic element 105 the combination with 15 influence of said armature,

currence of current above a predetermined amount the path of said flux is through said secondary poles. I 1

8. In a relay device, the combination with a rotatable armature, contacts controlled thereby, a torque-producing element for rotating saidarmature to contact-controlling position, an electromagnetic element producing a counter torque on said armature which normally overcomes the eflect of said torque element, poles for said counter-torque element between which said armature is rotatable, and means adjustable to operate in response to any predetermined abnormal condition to reduce the flux passing through said main poles whereby the effect of said torque element predominates.

9. In a relay device, the combination with a rotatable armature, contacts. controlled thereby, a torque-producing element for rotating said armature to contact-controlling position, an electromagnetic element producing a counter torque on said armature which normally overcomes the effect of said torque element, main poles for said counter-torque element providing a path for the flux through said armature, and leakage poles providing a shunt path for said flux without affecting said armature, and means whereby the normal path of said flux is'through said main poles but upon 'the occurrence of predetermined abnormal conditions the path of said flux is through said leakage poles.

- 10. In a relay device, the combination with a rotatable armature, contacts controlled thereby, a torque-producing element for, rotating said armature to contact-controlling osition, an electromagnetic element producing a counter torque on said armature -which normally overcomesthe efi'ect of said torque element, main poles for, said countermy hand this 23rd day of October, 1919.

HENRY G. FRENCH.

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