System for protection of dry type transformers

Patent metadata

Field	Value
Publication number	US-9882373-B2
Application number	US-201414550394-A
Country	US
Kind code	B2
Filing date	Nov 21, 2014
Priority date	Nov 21, 2014
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

A system for transient over voltage protection of a three-phase transformer. Two surge arresters are series connected across each winding of the transformer and the center point connection of the two surge arresters is electrically connected to a middle location of the winding. Three additional surge arresters are electrically connected from each phase to ground in the case of either a delta or Y connected transformer; and/or connected from a neutral point to ground in the case of a Y connected transformer. The system allows for all of the surge arresters to be packaged as an integrated surge arrester system to minimize induced transient over voltages and high stresses on the transformer winding due to internal resonances.

First claim

What is claimed is:

1. A system for transient over voltage protection of a three-phase transformer, the system comprising:
a dry-type transformer including first, second and third windings, each of the first, second and third windings having winding terminals;
a plurality of surge arresters divided into first, second and third groups, the first group of surge arresters connected across the first winding, the second group of surge arresters connected across the second winding, and the third group of surge arresters connected across the third winding;
each surge arrester of the first group being connected to at least one intermediate location along the first winding, the winding terminals of the first winding being connected to different surge arresters of the first group;
each surge arrester of the second group being connected to at least one intermediate location along the second winding, the winding terminals of the second winding being connected to different surge arresters of the second group; and
each surge arrester of the third group being connected to at least one intermediate location along the third winding, the winding terminals of the third winding being connected to different surge arresters of the third group.

2. The system according to claim 1 , wherein the first, second and third windings are interconnected in one of: a delta-connected configuration or a Y-connected configuration.

3. The system according to claim 2 , further comprising:
three surge arresters each having a first end and a second end;
the first ends being electrically connected to a start winding terminal or an end winding terminal of the first winding, second winding and third winding, respectively;
the second ends being electrically connected to ground.

4. The system according to claim 1 , further comprising circuit breakers coupled to each phase of the dry-type transformer.

5. The system according to claim 4 wherein the circuit breakers comprise vacuum circuit breakers.

6. The system according to claim 3 , wherein the surge arresters of the first group are positioned in a first housing, the surge arresters of the second group are positioned in a second housing, and the surge arresters of the third group are positioned in a third housing.

7. The system according to claim 6 , wherein each of the first, second and third housings comprises first and second ends, and the second end of each of the first, second and third housings is mechanically connected to a plate.

8. The system according to claim 6 , wherein the first group comprises a first surge arrester and a second surge arrester, the second group comprises a third surge arrester and a fourth surge arrester, and the third group comprises a fifth surge arrester and a sixth surge arrester; and
wherein the first housing comprises at least three terminals, a first terminal corresponding to a first end of the first surge arrester, a second terminal corresponding to second ends of the first and second surge arresters, and a third terminal corresponding to a first end of the second surge arrester.

9. The system according to claim 8 , wherein said three surge arresters comprise a seventh surge arrester, an eighth surge arrester, and a ninth surge arrester, said seventh surge arrester is positioned in the first housing, and the first housing further comprises a fourth terminal, wherein the third terminal corresponds to a first end of the seventh surge arrester and the fourth terminal corresponds to a second end of the seventh surge arrester.

10. The system according to claim 9 , wherein the second housing comprises at least three terminals, a first terminal of the second housing corresponding to a first end of the third surge arrester, a second terminal of the second housing corresponding to second ends of the third and fourth surge arresters, and a third terminal of the second housing corresponding to a first end of the fourth surge arrester.

11. The system according to claim 10 , wherein said eighth surge arrester is positioned in the second housing, and the second housing further comprises a fourth terminal, wherein the third terminal of the second housing corresponds to a first end of the eighth surge arrester and the fourth terminal of the second housing corresponds to a second end of the eighth surge arrester.

12. The system according to claim 11 , wherein the third housing comprises at least three terminals, a first terminal of the third housing corresponding to a first end of the fifth surge arrester, a second terminal of the third housing corresponding to second ends of the fifth and sixth surge arresters, and a third terminal of the third housing corresponding to a first end of the sixth surge arrester.

13. The system according to claim 12 , wherein said ninth surge arrester is positioned in the third housing, and the third housing further comprises a fourth terminal, wherein the third terminal of the third housing corresponds to a first end of the ninth surge arrester and the fourth terminal of the third housing corresponds to a second end of the ninth surge arrester.

14. The system according to claim 13 , wherein the fourth terminals of the first, second and third housings are electrically connected to said plate.

15. The system according to claim 14 wherein the plate is electrically connected to ground.

16. The system according to claim 14 , wherein the plate is electrically connected to the end winding terminals of the first, second and third windings.

17. The system according to claim 1 , wherein each of the first, second and third windings has a start winding terminal and an end winding terminal, and a distance from the start winding terminal to the end winding terminal is length (L), wherein the intermediate location of the first, second and third windings is located in a range of from L/4 to 3(L/4).

18. A system for transient over voltage protection of a three-phase, delta-connected transformer, the transformer including first, second and third windings, the system comprising:
a first surge arrester having first and second ends;
a second surge arrester having first and second ends;
said first end of said first surge arrester electrically connected to a first end of the first winding, and the second end of the first surge arrester electrically connected to an intermediate location of the first winding;
said first end of said second surge arrester electrically connected to a second end of the first winding, and the second end of the second surge arrester electrically connected to the intermediate location of the first winding;
a third surge arrester having first and second ends;
a fourth surge arrester having first and second ends;
said first end of said third surge arrester electrically connected to a first end of the second winding, and the second end of the third surge arrester electrically connected to an intermediate location of the second winding;
said first end of said fourth surge arrester electrically connected to a second end of the second winding, and the second end of the fourth surge arrester electrically connected to the intermediate location of the second winding;
a fifth surge arrester having first and second ends;
a sixth surge arrester having first and second ends;
said first end of said fifth surge arrester electrically connected to a first end of the third winding, and the second end of the fifth surge arrester electrically connected to an intermediate location of the third winding;
said first end of said sixth surge arrester electrically connected to a second end of the third wind

Assignees

• Abb Schweiz Ag

Inventors

• Lindell Elisabeth
• Liljestrand Lars
• Greuter Felix

Classifications

• H02H9/005 Primary

  avoiding undesired transient conditions · CPC title

• H02H9/04

  responsive to excess voltage (lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T) · CPC title

• H01F27/343 Primary

  Preventing or reducing surge voltages; oscillations · CPC title

• H01F27/40

  Structural association with built-in electric component, e.g. fuse · CPC title