Three-phase electrical power measurement system including three transformers and a measurement circuit to calculate the power thereof

• US 6,373,238 B2
• Filed: 07/06/1998
• Issued: 04/16/2002
• Est. Priority Date: 07/06/1998
• Status: Expired due to Term

• Current Assignee: Veris Industries LLC (Schneider Electric SE)
• Original Assignee: Veris Industries LLC (Schneider Electric SE)
• Inventors: Lewis, Jim, Stoffregen, Paul
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US09/110,634
• Publication Number:
  US 20020014887A1
• Time in Patent Office: 1,380 Days
• Field of Search: 324/127, 324/117.R, 324/117.H, 324/126, 324/251, 324/252, 324/142, 324/158.1, 324/107, 327/73, 702/60, 702/62
• US Class Current: 324/107
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 29/16 Measuring asymmetry of polyphase networks

Abstract

A measurement system includes a first transformer enclosed within a first housing and magnetically linked to a first cable where the first transformer senses changing current within the first cable and in response produces a first output voltage. A second transformer is enclosed within a second housing and magnetically linked to a second cable where the second transformer senses changing current within the second cable and in response produces a second output voltage. A third transformer is enclosed within a third housing and magnetically linked to a third cable where third transformer senses a changing current within the third cable and in response produces a third output voltage. A measurement circuit is electrically connected to the combination of the first transformer to receive a first input signal representative of the first output voltage, the second transformer to receive a second input signal representative of the second output voltage, and the third transformer to receive a third input signal representative of the third output voltage. The measurement circuit calculates an output value representative of electrical power within the first, second, and third cables in response to receiving the first, second, and third input signals. The measurement circuit is enclosed within at least one of the first housing, the second housing, and the third housing.

Claims

1. A measurement system comprising:

(a) a first transformer enclosed within a first housing and magnetically linked to a first cable, said first transformer sensing changing signal within said first cable and in response producing a first output signal;

(b) a second transformer enclosed within a second housing and magnetically linked to a second cable, said second transformer sensing changing signal within said second cable and in response producing a second output signal;

(c) a third transformer enclosed within a third housing and magnetically linked to a third cable, said third transformer sensing changing signal within said third cable and in response producing a third output signal;

(d) a measurement circuit electrically connected to the combination of said first transformer to receive a first input signal representative of said first output signal, said second transformer to receive a second input signal representative of said second output signal, and said third transformer to receive a third input signal representative of said third output signal;

(e) said measurement circuit calculating an output value representative of electrical power within said first, second, and third cables in response to receiving said first, second, and third input signals;

(f) said measurement circuit enclosed within at least one of said first housing, said second housing, and said third housing; and

said first housing, said second housing, and said third housing free from being maintained in a rigid relationship with respect to each other.

2. The measurement system of claim 1 wherein said first transformer includes a split core.

3. The measurement system of claim 2 wherein said split core includes two portions that are hingably attached to one another.

4. The measurement system of claim 1 wherein said first output signal and said second output signal are approximately 120 degrees apart, said second output signal and said third output signal are approximately 120 degrees apart, and said third output signal and said first output signal are approximately 120 degrees apart.

5. The measurement system of claim 1 wherein said first, second, and third transformers are located within a power box containing an electrical panel.

6. The measurement system of claim 1 wherein,

(a) said measurement circuit is enclosed within said third housing;

(b) said first transformer is electrically connected to said measurement circuit by a first pair of wires;

(c) said second transformer is electrically connected to said measurement circuit by a second pair of wires; and

(d) at least one of said first pair of wires having an exterior appearance that is different than at least one of said second pair of wires.

7. The measurement system of claim 6 wherein,

(a) a third wire is directly electrically connected to said first cable;

(b) a fourth wire is directly electrically connected to said second cable;

(c) a fifth wire is directly electrically connected to said third cable;

(d) said third wire having an exterior appearance that matches at least one of said first pair of wires;

(e) said fourth wire having an exterior appearance that matches at least one of said second pair of wires; and

(f) said fifth wire having an exterior appearance that is different than the exterior appearances of said third wire and said fourth wire.

8. A method of measuring power usage comprising the steps of:

(a) locating a first transformer enclosed within a first housing and magnetically linked to a first cable within a power box where said first transformer senses a changing signal within said first cable and in response produces a first output signal;

(b) locating a second transformer enclosed within a second housing and magnetically linked to a second cable within said power box where said second transformer senses a changing signal within said second cable and in response produces a second output signal;

(c) locating a third transformer enclosed within a third housing and magnetically linked to a third cable within said power box where said third transformer senses a changing signal within said third cable and in response produces a third output signal;

(d) receiving in a measurement circuit a first input signal representative of said first output signal from said first transformer, a second input signal representative of said second output signal from said first transformer, and a third input signal representative of said third output signal from said third transformer;

(e) said measurement circuit calculating an output value representative of electrical power flowing within said first, second, and third cables in response to receiving said first, second, and third input signals;

(f) locating said measurement circuit within at least one of said first housing, said second housing, and said third housing; and

(g) maintaining said first housing, said second housing, and said third housing free from a rigid relationship with respect to each other.

9. The method of claim 8 wherein said first transformer includes a split core.

10. The method of claim 9 wherein said split core includes two portions that are hingably attached to one another.

11. The method of claim 8 wherein said first output signal and said second output signal are approximately 120 degrees apart, said second output signal and said third output signal are approximately 120 degrees apart, and said third output signal and said first output signal are approximately 120 degrees apart.

12. The method of claim 8 wherein said first, second, and third transformer are located within said power box including an electrical panel.