Voltage sensing device for use at high voltage

• US 4,002,976 A
• Filed: 04/01/1975
• Issued: 01/11/1977
• Est. Priority Date: 04/01/1975
• Status: Expired due to Term

• Current Assignee: S&C Electric Company
• Original Assignee: S&C Electric Company
• Inventors: Zulaski, John A.
• Primary Examiner(s): Demeo, Palmer C.
• Assistant Examiner(s): Sunderdick, Vincent J.
• Application Number:
  US05/564,109
• Time in Patent Office: 651 Days
• Field of Search: 324/126, 324/127, 336/70, 336/90, 323/74, 323/76, 323/93, 174/137, 174/11 BH
• US Class Current: 324/126
• CPC Class Codes: G01R 15/06 having reactive components, e.g. capacitive transformer

Abstract

A compact voltage sensing device for connection to an alternating current high voltage circuit is imbedded within an organic polymeric insulator body that is formed to provide both mechanism support and "line to ground" insulation for a conductor or component connected thereto. The voltage sensing device comprises a capacitor and step-down transformer in series from the conductor to ground which provides a low voltage output which may be used to determine the magnitude of the voltage on the conductor, or as a source of control voltage for auxiliary apparatus. The insulator body may be made to be equal in height and have the same mounting configuration as a conventional insulator so that it can be substituted for a conventional insulator in a distribution system. The performance of the insulator body as insulation is not compromised by the presence of internal electrical components.

Claims

1. A voltage sensing device for providing a signal representative of the voltage between the high voltate side of a circuit and ground comprising:

a capacitor electrically connected at a first side to the high voltage side of the circuit;

a transformer having primary and secondary windings, said primary winding being serially connected between the second side of said capacitor and ground so that all of the current flowing through said capacitor also flows through said primary winding;

output terminals connected across said secondary winding;

an insulator body means formed of an electrically insulating material surrounding said capacitor and said transformer for providing line to ground insulation between the high voltage side of the circuit and ground;

whereby the signal representative of the voltage on the high voltage side of the circuit can be derived at said output terminals as well as electrical power for low-burden auxiliary apparatus.

2. A voltage sensing device, as claimed in claim 1, further comprising voltage limiting means electrically connected in parallel across said primary winding for limiting the voltage across said primary winding.

3. A voltage sensing device, as claimed in claim 1, wherein said insulator body means is formed of an organic polymeric compound.

4. A voltage sensing device, as claimed in claim 3, wherein said organic polymeric compound is a cast cycloaliphatic epoxy resin.

5. A voltage sensing device, as claimed in claim 1, wherein said insulator body means has surface elongating means formed around the periphery thereof to elongate the path between the high voltage side of the circuit and ground.

6. A voltage sensing device, as claimed in claim 1, wherein the ratio of said primary winding to said secondary winding is approximately 20 to 1.

7. A voltage sensing device, as claimed in claim 1, wherein said insulator body means is dimensioned and adapted to be physically interchangeable with a conventional support insulator.

8. A voltage sensing device, as claimed in claim 1, wherein said capacitor and said transformer are positioned side by side within said insulator body means so that said insulator body means can be dimensioned to a minimum volume while maintaining a substantially uniform voltage distribution within the insulating material of said insulator body means.

9. A voltage sensing device, as claimed in claim 1, wherein said transformer is coated with a semi-rigid curing compound to provide a mechanical buffer between said insulator body means and said transformer.

10. A voltage sensing device for providing a voltage signal representative of the voltage between the high voltage side of a circuit and ground comprising:

a first support terminal adapted to be connected to the high voltage side of the circuit;

a second support terminal adapted to be connected to ground;

a transformer mounted on said second support terminal, said transformer having primary and secondary windings, one side of said primary winding being connected to the second support terminal;

a capacitor electrically connected between said first support terminal and the other side of said primary winding;

voltage limiting means electrically connected in parallel across said primary winding;

first and second output terminals connected in parallel across said secondary winding;

an insulator body made of an electrically insulating material, said capacitor and said transformer being encased within said insulator body and said first and second support terminals being partially encased within said insulator body but partially extending from opposite surfaces of said insulator body, and said first and second output terminals being partially encased within said insulator body but partially extending from the surface of said insulator body,

whereby the voltage signal representative of the voltage on the high voltage side of the circuit can be derived at said output terminals.

11. A voltage sensing device, as claimed in claim 10, wherein said insulator body is formed of an organic polymeric compound.

12. A voltage sensing device, as claimed in claim 10, wherein said insulator body has insulator skirts formed around the periphery thereof.

13. A voltage sensing device, as claimed in claim 10, wherein said insulator body is dimensioned and adapted to be physically interchangeable with a conventional support insulator.

14. A voltage sensing device, as claimed in claim 10, wherein said capacitor and said transformer are positioned side by side within said insulator body so that said insulator body can be dimensioned to a minimum volume while maintaining a substantially uniform voltage distribution within the insulating material of said insulator body.

15. A voltage sensing device for providing a voltage signal representative of the voltage between the high voltage side of a circuit and ground comprising:

an insulator body molded of a first elevated temperature-curing polymeric compound, said insulator body means having formed therein a capacitor receiving cavity;

a capacitor positioned within the capacitor receiving cavity, one side of said capacitor being connected to the high voltage side of said circuit;

a second lower temperature-curing polymeric compound surrounding said capacitor and filling the capacitor receiving cavity, the temperature of curing of said second polymeric compound being low enough to avoid temperature and shrinkage force damage to the capacitor;

a transformer having primary and secondary windings molded within said insulator body, said primary winding being serially connected from the other side of said capacitor to ground;

output terminals partially imbedded in said insulator body and extending from a surface thereof, said output terminals being connected across said secondary winding;

whereby the voltage signal representative of the voltage on the high voltage side of the circuit can be derived at said output terminals.

16. A voltage sensing device, as claimed in claim 15, further comprising first and second spark gap electrodes electrically connected across said primary winding, said first and second spark gap electrodes being molded into said insulator body and partially extending from a surface of said insulator body in immediate proximity to one another so that an arc will form between said first and second spark gap electrodes to limit the voltage across said primary winding when the voltage across said primary winding exceeds a predetermined level.

17. A voltage sensing device, as claimed in claim 15, wherein said first elevated temperature-curing polymeric compound is a cast cycloaliphatic epoxy resin.

18. A method of fabricating a voltage sensing device having electrical components including a capacitor comprising the steps of:

molding an insulator body from a first elevated temperature-curing polymeric compound so that a hollow capacitor receiving cavity is formed therein, and so that all electrical components except the capacitor are imbedded in the insulator body;

inserting the capacitor into the capacitor receiving cavity;

connecting the capacitor to the electrical components;

filling the capacitor receiving cavity with a second lower temperature-curing polymeric compound to completely enclose the capacitor in the insulator body, the temperature of curing of said second lower temperature-curing polymeric compound being lower enough to avoid temperature and shrinkage force damage to the capacitor;

whereby damage to the capacitor resulting from high temperatures and shrinkage forces associated with the first elevated temperature-curing polymeric compound is avoided.

19. A method of fabricating a voltage sensing device comprising:

the steps of;

connecting a first capacitor bus to a first support terminal;

connecting one side of a primary winding of a step-down transformer to a second support terminal;

connecting one side of a secondary winding of the step-down transformer to a first output terminal;

connecting one side of a secondary winding of the step-down transformer to a second output terminal;

molding an insulator body from a first elevated temperature-curing epoxy resin so that a hollow capacitor receiving cavity is formed therein and so that the first support terminal is imbedded therein and partially extends beyond a first surface of the insulator body, so that the transformer is entirely encased in the insulator body, so that the second support terminal is imbedded therein and partially extends beyond a second surface of the insulator body, and so that the first and second output terminals partially extend from a surface of the insulator body;

inserting a capacitor into the capacitor receiving cavity;

connecting one side of the capacitor to the first capacitor bus;

connecting a second capacitor bus from the other side of the capacitor to the other side of the primary winding;

filling the capacitor receiving cavity with a second lower temperature-curing epoxy resin to completely enclose the capacitor in the insulator body, the temperature of curing of said second lower temperature-curing epoxy resin being low enough to avoid temperature and shrinkage force damage to the capacitor,

whereby damage to the capacitor resulting from high temperatures and shrinkage forces associated with the first high temperature-curing epoxy resin is avoided.

20. A method, as claimed in claim 19, further comprising the steps of:

connecting a first spark gap electrode to one side of the primary winding;

connecting a second spark gap electrode to the other side of the primary winding;

molding the resin insulator body so that the first and second spark gap electrodes extend from a surface of the insulator body in immediate proximity to one another whereby excessive voltage across said primary winding will cause arcing between the spark gap electrodes externally of the insulator body.

21. A voltage sensing device comprising:

sensing means for providing output signals representative of the voltage on a high voltage side of an electrical circuit including a capacitor serially connected between the electrical circuit and one side of a primary winding of a transformer, the other side of said primary winding being connected to ground so that all of the current flowing in said capacitor also flows in said primary winding, said transformer also having a secondary winding that provides signals representative of the voltage on the high voltage side of the electrical circuit as well as electrical power for low-burden auxiliary apparatus;

an insulator body means formed of an electrically insulating polymeric material surrounding said sensing means for providing mechanical support for said sensing means, and for providing insulation between the high voltage side of the circuit and ground.

22. A voltage sensing device for providing a signal representative of the voltage between a first and a second terminals comprising:

a capacitor electrically connected at a first side to the first terminal;

a transformer having primary and secondary windings, said primary winding being serially connected between the second side of said capacitor and the second terminal so that all of the current flowing through said capacitor flows through said primary winding;

output terminals connected across said secondary winding;

an insulator body means formed of electrically insulating material surrounding said capacitor and said transformer for providing insulation between the first and second terminals;

whereby the signal representative of the voltage between the first and second terminals can be derived at said output terminals as well as electrical power for low-burden auxiliary apparatus.