Clamp for measuring an electrical current flowing in conductors

• US 6,541,955 B2
• Filed: 07/11/2001
• Issued: 04/01/2003
• Est. Priority Date: 01/12/1999
• Status: Expired due to Term

• Current Assignee: Universal Technic
• Original Assignee: Universal Technic
• Inventors: Landre, Bernard
• Primary Examiner(s): Cuneo, Kamand
• Assistant Examiner(s): Nguyen, Jimmy
• Application Number:
  US09/889,043
• Publication Number:
  US 20030006754A1
• Time in Patent Office: 629 Days
• Field of Search: 324/127, 324/117.R, 324/117.H, 324/129, 324/149, 324/116, 324/126, 324/378, 324/115, 324/158.1, 324/121.R, 364/483, 364/481
• US Class Current: 324/127
• CPC Class Codes: G01R 1/22 Tong testers acting as secondary windings of current transformers

Abstract

A clamp for measuring an electric current flowing in conductors, the clamp comprising first and second jaws (1, 2) interconnected by a hinge axis (3) to be movable between a closed position and an open position, the jaws being provided respectively with first and second annular magnetic circuit segments (4, 5), each segment (4, 5) having a proximal end (7, 8) and a distal end (9, 10) relative to the hinge, and at least the first segment (5) being mounted to rock about a rocker axis (6) parallel to a hinge axis (3), the clamp including spacer means (12) for spacing the proximal ends (7, 8) apart, which spacer means are active at least when the distal ends (9, 10) are spaced apart by a distance that is greater than or equal to a predetermined safety distance.

Claims

1. A measuring clamp for measuring an electric current carried by conductors, the clamp comprising first and second jaws (1, 2) associated with at least one drive member (25, 26), the jaws (1, 2) being connected together by a hinge (3) and being provided with respective first and second segments (4, 5) of an annular magnetic circuit, each segment (4, 5) having a proximal end (7, 8) and a distal end (9, 10) relative to the hinge, and at least the first segment (5) being mounted to rock about a rocker axis (6) parallel to a hinge a axis (3), the jaws being movable about the hinge axis under the action of the drive member between a closed position in which the distal ends (9, 10) and the proximal ends (7, 8) of the segments (4, 5) are respectively in contact, and an open position in which the distal ends (9, 10) and the proximal ends (7, 8) are spaced apart, the clamp including spacer member (12) movable between an active position in which the spacer member has a cam-forming portion (13) co-operating at least with the proximal end (8) of the first segment (5) to space it apart positively from the proximal end (7) of the second segment (4) at least while the distal ends (9, 10) are spaced apart by a distance that is greater than or equal to a predetermined safety distance, and an inactive position in which the spacer member (12) releases relative movement between the segments.

2. A measuring clamp according to claim 1, wherein the spacer member (12) in the inactive position is associated with a stop (16) for locking the jaws closer than an intermediate open position in which the distal ends (9, 10) are spaced apart by a distance equal to the safety distance, and wherein the spacer member in the active position escapes from this stop.

3. A measuring clamp according to claim 2, wherein the spacer member (12) is mounted to slide on the first jaw (5) and the stop (16) forms a part of the second jaw (4), the spacer member having an end (14) opposite its cam-forming end and extending to face the stop when the jaws (1, 2) are in the closed position, and when the spacer member is in the inactive position so that the stop opposes opening of the jaws, said end (14) of the spacer member being withdrawn from the stop when the spacer member is in the active position.

4. A measuring clamp according to claim 3, wherein the end (14) opposite from the cam-forming end (13) is in the form of a pusher suitable for being operated manually.

5. A measuring clamp according to claim 1, wherein the spacer member (12) extends between at least one cam surface carried by one jaw (1, 2) and an adjacent projection (20, 21) at the proximal end (7, 8) of a magnetic circuit segment mounted to rock on the corresponding jaw, the cam-forming portion (13) of the spacer member extending in register with the corresponding projection of the magnetic circuit segment.

6. A measuring clamp according to claim 5, wherein each projection comprises a stud (20, 21) projecting laterally.

7. A measuring clamp according to claim 5, wherein the two segments (4, 5) of the magnetic circuit are mounted to rock on the corresponding jaws, and wherein the spacer member (12) has a tail (27) extending between the jaws beyond the cam-forming portion (13).