Flexible current sensor

• US 7,230,413 B2
• Filed: 10/19/2004
• Issued: 06/12/2007
• Est. Priority Date: 10/19/2004
• Status: Expired due to Fees

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Energy & Automation Incorporated (Siemens AG)
• Inventors: Zhang, Bin, Bilac, Mario
• Primary Examiner(s): Patel; Paresh
• Application Number:
  US10/968,463
• Publication Number:
  US 20060082356A1
• Time in Patent Office: 966 Days
• Field of Search: 324/127, 324/117.11, 324/117.12, 324/207.2, 324/251, 324/96
• US Class Current: 324/117.00R
• CPC Class Codes: G01R 1/22 Tong testers acting as secondary windings of current transformers
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils

Abstract

A method and a current sensor for measuring a current in a conductor. The sensor comprises a non-magnetic, flexible core member having a first end and a second end. A locking head having a channel therethrough is coupled to the first end of the core member. A first sensor conductor winding layer is mounted on the core member. Wherein the second end releasably engages the locking thread in the channel and adjustably configures the core member to surround the conductor as the second end is moved through the channel. In another embodiment the current sensor includes a locking tang within the channel and a plurality of sought tooth members on a portion of the core member and configured to selectively engage the locking tang as the second end of the core member is moved through the channel.

Claims

1. A current sensor for measuring a current in a conductor, the sensor comprising:

a non-magnetic, flexible core member having a first end and a second end;

a locking head having a channel therethrough, with the locking head coupled to the first end of the core member, the locking head including a locking tang within the channel and a plurality of saw tooth members on a portion of the core member and configured to selectively engage the locking tang as the second end of the core member is moved through the channel; and

a first sensor conductor winding layer mounted on the core member,

wherein the second end releaseably engages the locking head in the channel and adjustably configures the core member to surround the conductor as the second end is moved through the channel.

2. The current sensor of claim 1, wherein the locking head is integral with the core member as a single unit.

3. The current sensor of claim 1, including at least one additional sensor conductor winding layer positioned on the first sensor conductor winding layer.

4. The current sensor of claim 1, wherein the second end of the core member is narrower then the first end of the core member.

5. The current sensor of claim 1, wherein the core member is an elongated strip of material having a rectangular cross-section.

6. The current sensor of claim 1, wherein the current sensor is configured to couple to a signal processing circuit.

7. The current sensor of claim 1, wherein a loop formed with the flexible core member is defined with a variable diameter.

8. A method to sense electrical current in a conductor using a flexible current sensor operating in accordance with the Rogowski principle, with the current sensor being an elongated, flexible strip of material having a first end and a second end, a sensor conductor winding layer mounted on the flexible strip, and a locking head including a plurality of saw tooth members and having a channel therethrough coupled to one end of the flexible strip, the method comprising the steps of:

placing the flexible current sensor on the conductor in a perpendicular aspect to the longitudinal length of the conductor;

wrapping the second end of the flexible current sensor around the conductor in a loop;

inserting the second end into the channel;

pulling the second end through the channel to draw the flexible current sensor against the conductor and engaging the saw tooth members; and

sensing an induced voltage in the sensor conductor representative of the electrical current flowing in the conductor.

9. The method of claim 8, including the step of locking the second end of the flexible current sensor in the channel.

10. The method of claim 9, including the steps of unlocking the second end of the flexible sensor and removing the second end from the channel.

11. The method of claim 8, including the step of transmitting the sensed voltage to a signal processing circuit.

12. The method of claim 8, including the step of varying the diameter of the loop by moving the second end in the channel.

13. A current sensor device comprising:

a plastic cable tie of the type usable to wrap around one or more current transmission members, the plastic cable tie having a longitudinal axis and a portion for latching the plastic cable tie to itself; and

a sensor conductor winding wrapped around at least a portion of the plastic cable tie.

14. The current sensor of claim 13, wherein the cable tie has notches along at least a portion thereof wherein the portion for latching is engageable with the notches to resist motion of the portion for latching relative to the cable tie with more force in one direction of the motion than the opposite direction of motion.