Surge arrester having controlled multiple current paths
First Claim
Patent Images
1. A surge arrester comprising:
- a nonlinear resistive element having a first face and a second face that is spaced apart from said first face by the thickness of said element, wherein each of said faces includes a central portion surrounded by an outer portion, said resistive element having a longitudinal axis intersecting said first and second faces;
a first electrode adjacent to said first face;
a second electrode adjacent to said second face;
means for directing steady-state currents between said first electrode and said second electrode along a steady-state current path through said element that is formed at an angle relative to said axis;
means for directing surge currents between said first electrode and said second electrode through a solid portion of said element along a surge current path that is formed substantially parallel to said axis.
1 Assignment
0 Petitions
Accused Products
Abstract
An improved surge arrester includes metal oxide varistors in series with spark gap assemblies arranged such that the MOV elements conduct the low magnitude, steady-state current through the arrester along a path that is separate and distinct from the path through which impulse current is conducted during an overvoltage.
-
Citations
39 Claims
-
1. A surge arrester comprising:
-
a nonlinear resistive element having a first face and a second face that is spaced apart from said first face by the thickness of said element, wherein each of said faces includes a central portion surrounded by an outer portion, said resistive element having a longitudinal axis intersecting said first and second faces; a first electrode adjacent to said first face; a second electrode adjacent to said second face; means for directing steady-state currents between said first electrode and said second electrode along a steady-state current path through said element that is formed at an angle relative to said axis; means for directing surge currents between said first electrode and said second electrode through a solid portion of said element along a surge current path that is formed substantially parallel to said axis. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A surge arrester comprising:
-
a resistive element having a first face and a second face that is spaced apart from said first face by the thickness of said element, said resistive element having a steady-state current path between said first and second faces for conducting steady-state currents through said element and an impulse current path between said first and second faces separately defined from said steady-state current path for conducting surge currents through said element; means for directing surge currents through a solid portion of said resistive element along said impulse current path; and means for directing steady-state currents through said resistive element along said steady-state current path; wherein said resistive element comprises a nonlinear varistor of substantially uniform microstructure and wherein said steady-state current path is longer than said impulse current path.
-
-
9. A surge arrester comprising:
-
a nonlinear, voltage dependent resistive element having a longitudinal axis and a first surface and a second surface that is spaced apart from said first surface by the thickness of said resistive element, each of said surfaces having a central region and a peripheral region surrounding said central region; an impulse current path between said central region of said first surface and said central region of said second surface for conducting surge current through the arrester, said impulse current path being substantially parallel to said longitudinal axis; and a steady-state current path in said resistive element between said first and second surfaces for conducting steady-state current through the arrester, said steady-state current path in said resistive element being directed at an angle relative to said impulse current path. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. A surge arrester comprising:
-
a resistive element having a central axis and a first face and a second face that is axially spaced apart from said first face by the thickness of said resistive element, each of said faces having a central region and a peripheral region surrounding said central region; a first electrode in electrical contact with said peripheral region of said first face, said first electrode having a central portion that is axially spaced apart from said central region of said first face to form a first spark gap between said first electrode and said central region of said first face; and a second electrode in electrical contact with said central region of said second face, said second electrode having a peripheral portion axially spaced apart from said peripheral region of said second face to form a second spark gap between said second electrode and said peripheral region of said second face, said first electrode including a rim electrically engaging said peripheral region of said first face and a raised central portion electrically connected to said rim, said first spark gap being formed between said raised central portion and said first face.
-
-
22. A surge arrester comprising:
-
a plurality of nonlinear varistors stacked in columnar relationship and forming a varistor stack, said varistors including an upper and lower face and a central region and a peripheral region surrounding said central region on said faces; a plurality of series spark gaps in said varistor stack, said gaps being disposed between said central regions of adjacent varistors in said stack; means for electrically connecting in series said peripheral regions of said varistors, and means for directing steady-state currents through said varistor stack through said peripheral regions of said varistors and not through said central regions of said varistors; said varistor comprising a base portion and a crown portion formed on said peripheral region of said base, said connecting means comprising said crown; said crown being formed from a material having different electrical characteristics than the material used to form said base. - View Dependent Claims (23)
-
-
24. A surge arrester comprising:
-
a plurality of nonlinear varistors stacked in columnar relationship and forming a varistor stack, said varistors including an upper and lower face and a central region and a peripheral region surrounding said central region on said faces; a plurality of series spark gaps in said varistor stack, said gaps being disposed between said central regions of adjacent varistors in said stack; means for electrically connecting in series said peripheral regions of said varistors, and means for directing steady-state currents through said varistor stack through said peripheral regions of said varistors and not through said central regions of said varistors; said varistor comprising a base portion and a crown portion formed on said peripheral region of said base, said connecting means comprising said crown; said connecting means further comprising a semiconductor material disposed on top of said crown.
-
-
25. A surge arrester comprising:
-
a plurality of nonlinear varistors stacked in columnar relationship and forming a varistor stack, said varistors including an upper and lower face and a central region and a peripheral region surrounding said central region on said faces; a plurality of series spark gaps in said varistor stack, said gaps being disposed between said central regions of adjacent varistors in said stack; means for electrically connecting in series said peripheral regions of said varistors, and means for directing steady-state currents through said varistor stack through said peripheral regions of said varistors and not through said central regions of said varistors; said varistor comprising a base portion and a crown portion formed on said peripheral region of said base, said connecting means comprising said crown; an electrode disposed between said varistors, said electrode including a rim and an offset portion connected to said rim, said series gap being formed between said offset portion and said central region of said varistor; wherein said connecting means further comprises a semiconductor material disposed between said crown and said rim of said electrical contact.
-
-
26. A surge arrester comprising:
-
a first and a second nonlinear resistive element, each of said resistive elements including a body comprising a core portion of nonlinear resistive material and an outer portion of nonlinear resistive material surrounding said core portion, wherein said core portions include a first face and a second face spaced apart from said first face by the thickness of said core portion; a housing retaining said resistive elements in a columnar relationship such that said second face of said first resistive element is spaced apart a predetermined distance from said first face of said second resistive element; means for directing surge currents through said bodies of said first and second resistive elements along a surge current path formed through said core portions of said first and second resistive elements, said surge current path not passing through said outer portions; means for directing steady-state currents through said bodies of said first and second resistive elements along a steady-state current path formed through said outer portions of said first and second resistive elements, said steady-state current path not passing through said core portions; and a conductive coating forming a contact surface on said first and second faces of said first and second resistive elements, said contact surfaces being substantially centrally positioned on said faces; a surrounding region on each of said first and second faces that surrounds said contact surfaces and that is free from said conductive coating. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
-
Specification