US3391371A - Overvoltage protective device - Google Patents

Overvoltage protective device Download PDF

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Publication number
US3391371A
US3391371A US563182A US56318266A US3391371A US 3391371 A US3391371 A US 3391371A US 563182 A US563182 A US 563182A US 56318266 A US56318266 A US 56318266A US 3391371 A US3391371 A US 3391371A
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United States
Prior art keywords
groove
coatings
depth
ceramic
air gap
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US563182A
Inventor
Harold E Wright
Edward E Leofsky
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Erie Technological Products Inc
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Erie Technological Products Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Erie Technological Products Inc filed Critical Erie Technological Products Inc
Priority to US563182A priority Critical patent/US3391371A/en
Priority to GB2912367A priority patent/GB1196953A/en
Priority to DE19671588160 priority patent/DE1588160C3/en
Application granted granted Critical
Publication of US3391371A publication Critical patent/US3391371A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T4/00—Overvoltage arresters using spark gaps
    • H01T4/10—Overvoltage arresters using spark gaps having a single gap or a plurality of gaps in parallel

Definitions

  • This invention is a ceramic overvoltage protective device having an air gap which breaks down to protect equipment from high voltage surges.
  • the construction is simple to make and its reliability is increased by a construction which protects the ceramic from tracking during voltage breakdown.
  • One use is in television receivers for protecting the color tube from voltage surges which may occur at infrequent intervals during the life of the tube.
  • FIG. 1 is a longitudinal section through the device at an initial stage of manufacture
  • FIG. 2 is a section on line 2-2 of FIG. 1
  • PG. 3 is a longitudinal section through the finished device.
  • the body of the device comprises a cylinder 1 of suitable ceramic such as steatite coated over its entire exterior surface with a metallic coating 2.
  • the ceramic bodies 1 are conveniently coated in bulk with a nickel or other metallic plating which may be built up to an additional thickness by electroplating copper and then tinned to accept solder.
  • the coating is not necessary on the end surfaces 3 but there is no particular advantage in masking the coating from the end surfaces.
  • the ceramic rod merely has an exterior metallized coating 2.
  • a circumferential groove 4 is cut into the ceramic at some point between the ends of the rod.
  • the depth of the groove is many times the thickness of the coating 2 and is at least equal to and usually greater than the axial width of the groove.
  • the depth of the groove was .016" and the width of the groove was .011.
  • This construction confines the voltage breakdown to a spark discharge in air between the ends 5, 6. Erosion of the metal during breakdown merely locally increases the axial length of the gap so that the next protective voltage breakdown occurs at a "ice different point. The discharge is out of contact with the ceramic, so the ceramic is not subject to tracking which could lower the insulation resistance of the ceramic.
  • the air gap between the ends 5, 6 is annular in form, surrounding the entire circumference of the device.
  • the groove 4 is easily cut by automatic machinery which chucks the ceramic body and moves it against a saw.
  • the axial Width of the groove is easily controlled by the width of the saw.
  • the depth of the groove is also easily controlled and is conveniently held to a value safely in excess of the minimum required.
  • the manufacture of the device is completed by soldering conventional metal end cap terminas 7 to opposite ends of the body. These terminals have associated leads 8 making electrical connections.
  • the terminal assembly operation is adapted to automation.
  • An overvoltage protective device comprising a cylindrical ceramic body having between its ends an inwardly extending circumferential groove of depth at least substantially equal to its axial Width, a pair of metallized coatings overlying the outer surface of the body, said coatings being axially spaced from each other by the groove to provide an annular air gap, said coatings extending respectively from opposite sides of the groove toward opposite ends of the body, the depth of the groove at least substentially equal to the axial width of the groove and being many times the thickness of the coatings whereby the sparking is confined to the air gap between the coatings and does not affect the breakdown voltage by tracking the ceramic.

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  • Insulators (AREA)
  • Thermistors And Varistors (AREA)
  • Emergency Protection Circuit Devices (AREA)

Description

United States Patent 3,391,371 OVERVOLTAGE PROTECTIVE DEVICE Harold E. Wright, Erie, and Edward E. Leofsky, Wesleyville, Pa., assignors to Erie Technological Products, Inc., Erie, Pa., a corporation of Pennsylvania Filed July 6, 1966, Ser. No. 563,182 2 Claims. (Cl. 337-417) This invention is a ceramic overvoltage protective device having an air gap which breaks down to protect equipment from high voltage surges. The construction is simple to make and its reliability is increased by a construction which protects the ceramic from tracking during voltage breakdown. One use is in television receivers for protecting the color tube from voltage surges which may occur at infrequent intervals during the life of the tube.
In the drawing, FIG. 1 is a longitudinal section through the device at an initial stage of manufacture, FIG. 2 is a section on line 2-2 of FIG. 1 and PG. 3 is a longitudinal section through the finished device.
The body of the device comprises a cylinder 1 of suitable ceramic such as steatite coated over its entire exterior surface with a metallic coating 2. The ceramic bodies 1 are conveniently coated in bulk with a nickel or other metallic plating which may be built up to an additional thickness by electroplating copper and then tinned to accept solder. The coating is not necessary on the end surfaces 3 but there is no particular advantage in masking the coating from the end surfaces. At this stage, the ceramic rod merely has an exterior metallized coating 2.
In the second stage of manufacture, a circumferential groove 4 is cut into the ceramic at some point between the ends of the rod. The depth of the groove is many times the thickness of the coating 2 and is at least equal to and usually greater than the axial width of the groove. In a commercial form designed for breakdown in the range of 1000-2000 volts, the depth of the groove was .016" and the width of the groove was .011. After this operation, there is an annular air gap between adjacent ends 5, 6 of the metallized coating 2. This construction confines the voltage breakdown to a spark discharge in air between the ends 5, 6. Erosion of the metal during breakdown merely locally increases the axial length of the gap so that the next protective voltage breakdown occurs at a "ice different point. The discharge is out of contact with the ceramic, so the ceramic is not subject to tracking which could lower the insulation resistance of the ceramic. The air gap between the ends 5, 6 is annular in form, surrounding the entire circumference of the device.
The groove 4 is easily cut by automatic machinery which chucks the ceramic body and moves it against a saw. The axial Width of the groove is easily controlled by the width of the saw. The depth of the groove is also easily controlled and is conveniently held to a value safely in excess of the minimum required.
The manufacture of the device is completed by soldering conventional metal end cap terminas 7 to opposite ends of the body. These terminals have associated leads 8 making electrical connections. The terminal assembly operation is adapted to automation.
We claim:
1. An overvoltage protective device comprising a cylindrical ceramic body having between its ends an inwardly extending circumferential groove of depth at least substantially equal to its axial Width, a pair of metallized coatings overlying the outer surface of the body, said coatings being axially spaced from each other by the groove to provide an annular air gap, said coatings extending respectively from opposite sides of the groove toward opposite ends of the body, the depth of the groove at least substentially equal to the axial width of the groove and being many times the thickness of the coatings whereby the sparking is confined to the air gap between the coatings and does not affect the breakdown voltage by tracking the ceramic.
2. The device of claim 1 in which the body is overcoated with a metallized coating and the circumferential groove is cut through the coating into the body to divide the coating into said pair of axially spaced coatings and to provide a sharply defined annular air gap.
References Cited UNITED STATES PATENTS 2,288,428 6/ 1942 Babler 200-l 15 BERNARD A. GILHEANY, Primary Examiner.
F. E. BELL, Assistant Examiner.

Claims (1)

1. AN OVERVOLTAGE PROTECTIVE DEVICE COMPRISING A CYLINDRICAL CERAMIC BODY HAVING BETWEEN ITS ENDS AN INWARDLY EXTENDING CIRCUMFERENTIAL GROOVE OF DEPTH AT LEAST SUBSTANTIALLY EQUAL TO ITS AXIAL WIDTH, A PAIR OF METALLIZED COATINGS OVERLYING THE OUTER SURFACE OF THE BODY, SAID COATINGS BEING AXIALLY SPACED FROM EACH OTHER BY THE GROOVE TO PROVIDE AN ANNULAR AIR GAP, SAID COATINGS EXTENDING RESPECTIVELY ENDS OF THE BODY, THE DEPTH OF THE GROOVE TOWARD OPPOSITE ENDS OF THE BODY, THE DEPTH OF THE GROOVE AT LEAST SUBSTANTIALLY EQUAL TO THE AXIAL WIDTH OF THE GROOVE AND BEING MANY TIMES THE THICKNESS OF THE COATINGS WHEREBY THE SPARKING IS CONFINED TO THE AIR GAP BETWEEN THE COATINGS AND DOES NOT AFFECT THE BREAKDOWN VOLTAGE BY TRACKING THE CERAMIC.
US563182A 1966-07-06 1966-07-06 Overvoltage protective device Expired - Lifetime US3391371A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US563182A US3391371A (en) 1966-07-06 1966-07-06 Overvoltage protective device
GB2912367A GB1196953A (en) 1966-07-06 1967-06-23 Spark Gap
DE19671588160 DE1588160C3 (en) 1966-07-06 1967-07-06 Surge protection device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US563182A US3391371A (en) 1966-07-06 1966-07-06 Overvoltage protective device

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US3391371A true US3391371A (en) 1968-07-02

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3961225A (en) * 1974-02-26 1976-06-01 Mitsubishi Mining & Cement Company, Ltd. Surge absorber
FR2301915A1 (en) * 1975-02-22 1976-09-17 Mitsubishi Mining & Cement Co DEVICE FOR ABSORBING OVERVOLTAGES
US4317155A (en) * 1979-03-27 1982-02-23 Mikio Harada Surge absorber
DE4111687A1 (en) * 1991-04-10 1992-10-15 Phoenix Elekt Fuse module for electronic measuring or communications appts. - has fuse element and series inductance parallel to replaceable discharge path
US20060255897A1 (en) * 2003-05-08 2006-11-16 Hideki Tanaka Electronic component, and method for manufacturing the same

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2288428A (en) * 1939-06-20 1942-06-30 Babler Egon Device for protecting electrical apparatus from voltage surges

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2288428A (en) * 1939-06-20 1942-06-30 Babler Egon Device for protecting electrical apparatus from voltage surges

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3961225A (en) * 1974-02-26 1976-06-01 Mitsubishi Mining & Cement Company, Ltd. Surge absorber
FR2301915A1 (en) * 1975-02-22 1976-09-17 Mitsubishi Mining & Cement Co DEVICE FOR ABSORBING OVERVOLTAGES
US4317155A (en) * 1979-03-27 1982-02-23 Mikio Harada Surge absorber
DE4111687A1 (en) * 1991-04-10 1992-10-15 Phoenix Elekt Fuse module for electronic measuring or communications appts. - has fuse element and series inductance parallel to replaceable discharge path
US20060255897A1 (en) * 2003-05-08 2006-11-16 Hideki Tanaka Electronic component, and method for manufacturing the same
US7884698B2 (en) * 2003-05-08 2011-02-08 Panasonic Corporation Electronic component, and method for manufacturing the same

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