US1224408A - Electrical protective device. - Google Patents

Description

L.' M. PERKINS. ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED OCT. 30. I916.

Patented May 1, 1917.

INVENTOR L aarence A Per/rm s.

ATTORNEY UNITED STATES PATENT OFFICE.

LAURENCE M. PERKINS, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELEC'IRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

ELECTRICAL PROTECTIVE DEVICE.

Application filed October 30, 1916.

To all whom it may concern:

Be it known that I, Lannnnon M. PER- KINS, a citizen of the United States, and a resident of IVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electrical Protective Devices, of which the following is a specification.

My invention relates to electrical protective devices and particularly to means for protecting electrical translating devices in accordance with the temperatures thereof.

The object of my invention is to provide a device of the above-indicated character that shall operate when the difference in the energy loss in a portion of the translating device that is to be protected and the energy loss in a resistor, that normally bears a predetermined relation to the energy loss in the translating device, exceeds a predetermined value.

In the carrying out of my invention, I connect a resistor having a substantially constant resistance to a portion of a translating device that is to be protected, and I so connect an electro-responsive device or a relay to. the resistor and the translating device that it is actuated in accordance with the relative difference in the energy loss in the resistor and a portion of the translating device. That is, the relay will operate backwardly so long as the ratio of the losses in the translating device and the resistor is below a predetermined value; will remain stationary when the ratio of the losses is a predetermined value and will operate to trip a circuit interrupter, control a signal device or indicate the temperature of the translating device when its load so changes I that the ratio of its energy loss to the energy loss in the resistor exceeds a predetermined value.

Figure 1 of the accompanying drawings is a diagrammatic view of a protective device embodying my invention, and Fig. 2 is a diagrammatic view of a modified form of the protective device embodying my invention.

In Fig. 1 of the drawings, a relay 1 is provided for controlling the tripping of a circuit interrupter 2 when the temperature of a field-magnet winding 8, or other translating device, reaches a predetermined value.

A circuit 4, comprising a resistor 5, a reactor fiend a an fo m r Wind ng 'Z, i

Specification of Letters Patent.

Patented. May 1, 1917.

Serial No. 128,414.

a substantially constant resistance of suchvalue that the energy losses in the circuit 4:

and in the winding 3 will be the same or have a constant ratio under predetermined conditions. That is, the resistor 5 is so proportioned that the energy loss therein is equal or proportional to the energy loss in the winding 3 at a predetermined temperature. However, since the resistance of the resistor is adapted to be constant under all conditions of temperature, when an excessive load traverses the winding 3, its resistance will increase and its energy loss will be relatively greater than the energy loss in the circuit l.

A transformer winding 8 is so connected to the winding 3 that current proportional to the current traversing the winding 3 traverses the same. The transformer windings T and 8. are wound on a common magnetizable core member 7 and are so con nected that they oppose each other. A winding 8 is also wound. on the core member 7 and is connected to the winding 9 of the relay 1 for the purpose of supplying the same with current proportional to the difference in the currents traversing the windings 7 and S. A winding 10; of the relay 1 is operatively connected across the terminals of the winding 3 and the circuit t. Thus, the armaturel l of the relay 1 will developv a torque that is proportional to the relative difference between the energy consumed in the winding 3 and the circuit 4:.

W hen a relatively smallcurrent traverses the winding 3, the armature 11 will turn in a counter-clockwise direction until its movable contact member 12 engages a stationary stop 13. At a predetermined value 0t cur rent, traversing the winding 3, the ratio of the currents traversing the winding 3 and the circuit t will be such as to cause the armature 11 to remain stationary, and, when a relatively large amount of current traverses the Winding 3, the armature 11 will turn, in a clockwise direction, tocause its movable contact member 12 to engage a stationary contact member 14:. The contact members 12 and let constitute the separable terminals of a circuit 15 comprising a source 16 of electromotive force and the winding 17 of a tripping electromagnet 18. Thus, when the temperature of the winding 3 reaches a adapted to cooperate with a scale 12 for thepurpose of indicating, between predetermined limits, the temperature of the device 3.

In Fig. 2 of the drawings, a transformer 19, having a primary winding 20 and a secondary winding 21, is adapted to be protected by a circuit interrupter 22 that is controlled by a relay 23.

The relay 23 comprises a magnetizable core member 24, windings 25 and 26, an armature 27 and movable and stationary contact members 28 and 29. A transformer winding 30 that is adapted to be supplied with current proportional to the current traversing the secondary winding 21 of the transformer 19 is disposed on a magnetizable core member 41. A transformer winding 31, a transformer winding 32 and a transformer winding 33 are also disposed on the magnetizable core member 41. The transformer winding 32 is adapted to be supplied with current proportional to the current traversing the primary winding 20 of the transformer 19, and the transformer winding 33 is adapted to be supplied with current proportional to the drop in potential across the winding 20 of the transformer 19. The windings 30, 31, 32 and 33 are so connected that a winding 42, which is also associated with the core member 41 and operatively connected to the winding 25 of the relay 23, will be supplied with current proportional to the resultant current traversing the two windings of the transformer 19 compensated by an amount proportional to the iron loss in the transformer 19, as determined by the transformer winding 33.

The primary winding of a transformer 34 is operatively connected across the terminals of the winding 20 and, the primary Winding of a similar transformer 35 is operatively connected across the terminals of the winding 21. The secondary windings of the transformers 34 and 35 are connected in opposition to each other and the circuit, thus constituted, is connected to the winding 26 of the relay 23. A circuit 36, comprising a reactor 37 a resistor 38 having a substantially constant resistance and the transformer winding 31, is connected in shunt relation to the winding 26. Since the secondary windings of the transformers 34 and 35 oppose each other, the net or resultant voltage impressed across the winding 26 represents the voltage loss or drop in the transformer 19. In other words, the transformers 34 and 35 are so proportioned that the resultant voltage represents the drop in each of the windings in the transformer 19 reduced to a common voltage. The energy corresponding to this voltage and the sum of the currents in the primary and second ary windings 20 and 21 is the RI loss plus the iron loss in the transformer 19. The current that traverses the circuit 36 is produced by this voltage and has a constant phase angular relation therewith. If the loss due to resistance in the transformer 19 and its iron loss are proportional to the square of the current, the voltage drop will have a constant phase-angular relation to the current that traverses the winding 20. Any change in the resistance of the windings 2i) and 21 so changes the phase-angular re.ation of the voltage drop with respect to the current that traverses the winding 20 that the phase-angular relation between the current which traverses the winding 29 and the current which traverses the circuit so must, necessarily, ehai'ige. As the phaseangular relation changes, the resultant current or the current that traverses the transformer winding 31 changes in sign and, consequently, the armature 27 will be caused to turn in the one or the other direction according to the sign of the current that traverses the transformer 31. In other words, when the energy loss in the transformer 19 exceeds, or bears a predetermined relation to, the energy loss in the resistor 38, the contact member 28 will engage the contact member 29 to complete a circuit through the winding 39 of a tripping electromagnet 40.

It will be understood that, if the currents traversing the windings 20 and 21 are eX- actly 180 out of phase, the one or the other of the transformer winding 30 and 32 may be omitted. Also, the movable contact member 28 may be adapted to cooperate with a scale 43 to indicate the temperature of the transformer 19.

I do not limit my invention to the particular systems illustrated, as it is adaptable to various modifications without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim as my invention:

1. In an electrical system, the combination with a translating device and a protective. device, of a resistor having substan tially constant resistance, a relay for controlling the protective device, and means for so connecting the relay to the translating device and the resistor that it is actuated in accordance with the difference in the energy loss in the resistor and the translating device.

2. The combination with a translating device and a resistor having substantially constant resistance operatively connected thereto, of an electro-responsive device, and means for so connecting the electro-responsive device to the resistor and the translating device that it will be actuated in accordance with the diiierence in the energy loss in the resistor and the translating device.

3. The combination with a translating device and a resistor having a predetermined energy loss, of a reverse-energy relay one winding of which is supplied with energy in accordance with the relative diiierence in energy loss in the said resistor and a portion of the translating device.

4;. The combination with a translating device and a resistor, of means for determining the ratio of the energy losses in the translating device and the resistor, and an electro-responsive device adapted to be actuated when the translating device reaches such temperature that the ratio of the energy losses is greater than a predetermined value.

5. In an electric circuit, the combination with a translating device and a resistor connected to the circuit, of a reverse-energy relay one winding of which is supplied with current proportional to the relative difference in the currents traversing the resistor and the translating device and the other winding of which is supplied with current proportional to the voltage impressed across the resistor and the translating device.

6. In an electric circuit, the combination with a translating device and a resistor connected to the circuit, of a reverse-energy relay one winding of which is supplied with current proportional to the relative difference in the currents traversing the resistor and a portion of the translating device and the other winding of which is supplied with current proportional to the voltage impressed across the resistor and the portion of the translating device.

Copies of this patent may be obtained for 7.-In an electric circuit, the combination with a translating device, of a resistor the energy loss of which bears a predetermined relation to the energy loss in a portion of the translating device, under predetermined conditions, and means adapted to be actuated when the ratio of the energy loss in that portion of the translating device to the energy loss in the resistor exceeds a predetermined value.

8. In an electric circuit, the combination with a translating device and a resistor, of a reverse-energy relay one winding of which is connected in parallel relation to the resistor and a portion of the translating device, a transformer one winding of which is supplied with current proportional to the current traversing the resistor, a second winding of which is supplied with current proportional to the current traversing a. portion of the translating device and a third winding of which is so connected to the other winding of the relay that only the diflerence in the currents traversing the resistor and the translating device traverses the same.

9. In an electrical system, the combination with a translating device and an electroresponsive device, of a resistor having a substantially constant resistance, the energy loss in the said resistor being adapted to bear a predetermined relation to the energy loss in the translating device, and means for so connecting the electro-responsive device to the resistor and the translating device that the electro-responsive device will be actuated in accordance with the relative difference in the energy loss in the resistor and the translating device.

In testimony whereof, I have hereunto subscribed my name this 24th day of Oct.

LAURENCE M. PERKINS.

five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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