Capacitive pickup device for pulsating high voltage measurements

• US 4,052,665 A
• Filed: 03/30/1976
• Issued: 10/04/1977
• Est. Priority Date: 03/30/1976
• Status: Expired due to Term

• Current Assignee: Snap-On Tools Company LLC (Snap-On Incorporated)
• Original Assignee: Snap-On Tools Company LLC (Snap-On Incorporated)
• Inventors: Gruenwald, Clifford F.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/672,257
• Time in Patent Office: 553 Days
• Field of Search: 324/51, 324/72.5, 324/61 P, 324/54, 324/126, 324/127, 324/133, 324/149, 324/17, 324/61 R
• US Class Current: 324/530
• CPC Class Codes: F02P 17/12 Testing characteristics of the spark, ignition voltage or current testing of sparking plugs H01T13/60
• CPC Class Codes: F02P 2017/006 using a capacitive sensor
• CPC Class Codes: G01R 15/16 using capacitive devices
• CPC Class Codes: G01R 19/155 Indicating the presence of voltage

Abstract

A capacitive pickup device for deriving a measurable voltage which is a linear function of the magnitude of pulsating high voltage of the order of 15 to 40 kilovolts in an insulated conductor, the pickup device having a pair of electrically conducting plate members connected together electrically to form one plate element of a capacitor, the conductor itself forming the other plate element of the capacitor and the conductor insulation forming the dielectric. The pickup device also includes a pair of electrically conducting plates respectively carried in spaced relation with the plate members, the plates being centrally relieved to accommodate the plate members and adapted to be connected to ground. An indicating and protective gaseous conduction lamp is electrically connected between the plate members and plates, and a capacitor and a resistor are connected in parallel across the lamp to form an output circuit for connection to apparatus for indicating in linear manner the magnitude of the high voltage in the conductor. The plate members and plates are relatively movable so they selectively may open and close for receiving a portion of the insulated conductor without requiring conductor disconnection.

Claims

1. A capacitive pickup device for deriving a measurable voltage which is a linear function of the magnitude of pulsating high voltage in an insulated conductor, comprising:

a pair of electrically conducting generally semicylindrical plate members connected together electrically to form a first plate element of a capacitor;

means mounting said plate members for relative movement so they selectively may open for receiving an insulated conductor without requiring conductor disconnection and close to form substantially a cylinder closely encircling the conductor, the conductor forming a second plate element of the capacitor and the insulation thereon forming the dielectric between the two plate elements;

a pair of electrically insulating members having concave faces respectively secured to the convex faces of said plate members and extending beyond the ends of said plate members;

a pair of electrically conducting generally semicylindrical plates respectively secured to the concave faces of said insulating members in spaced relation with said plate members, said plates centrally relieved to accommodate said plate members and adapted to be connected to ground, said plates functioning to minimize the fringing effects of extraneous electric fields on the voltage appearing on said plate members; and

voltage limiting output means electrically connected between said plate members and said plates to provide high voltage protection to the user and associated apparatus and to form an output circuit for connection to apparatus for indicating in linear manner the magnitude of the high voltage in the conductor.

2. The capacitive pickup device of claim 1 wherein the electrical connections between said plate members and said lamp and said plates and said lamp are components of a shielded cable with the shield thereof adapted to be connected to ground.

3. The capacitive pickup device of claim 1 wherein said means mounting said plate members for relative movement comprise a pair of elongated manual members pivoted together intermediate the ends thereof, said plate members disposed in opposing relation on corresponding ends of said manual members, the other corresponding ends serving as handles.

4. The capacitive pickup device of claim 3 with the addition of spring means extending between said pivoted manual members, said spring means urging said manual members in direction to close said plate members.

5. The capacitive pickup device of claim 3 wherein said plate members and said pivoted manual members are integral, and with the addition of a sleeve of electrically insulating material on the handle of each manual member.

6. The capacitive pickup device of claim 1 wherein said voltage limiting output means comprises a gaseous conduction lamp electrically connected between said plate members and said plates and adapted to indicate by flickering when the pickup device is exposed to punctured conductor insulation, and a capacitor and a resistor connected in parallel across said lamp.