Device for the two-way inductive coupling of data signals to a power line
The device comprises a current transformer having a ring-shaped magnetic core ( 10 ) internally defining an opening ( 15 ) for the arrangement of a power line ( 2 ) and a winding wound onto the core ( 10 ), the core ( 10 ) being split into at least two core segments (A, B) articulated to one another. Both core segments (A, B) are furthermore optimized with regard to surface finish and form factor to allow low attenuation in the low-frequency data signal between 50 kHz and 600 kHz transmitted to the power grid.
1. A device for the two-way inductive coupling of data signals to a low- or medium-voltage power line ( 2 ), comprising:
a ring-shaped magnetic core ( 10 ) split into at least a first ring-shaped core segment (A) and a second ring-shaped core segment (B) articulated to one another, said ring-shaped magnetic core ( 10 ) defining an opening ( 15 ) for the arrangement therethrough of said power line ( 2 ), and each of said ring-shaped core segments (A, B) defining two end planar faces ( 11 A, 12 A, 11 B, 12 B) which define separating gaps ( 11 ) and ( 12 ) when they are opposite one another and when said ring-shaped core segments are surrounding said electric power line ( 2 );
a connector ( 30 ) for a coaxial cable for inputting and conducting said low-frequency data signal; and
a winding wound onto said ring-shaped magnetic core ( 10 ) receiving said data signal from the connector ( 30 ) and determining together with the power line ( 2 ) a current transformer coupling said data signal between said power line ( 2 ) and said winding through the ring-shaped magnetic core ( 10 );
characterized in that said ring-shaped magnetic core ( 10 ) is made of a ferromagnetic material with the following properties:
1500<ui<150000
1.2 T<Bsat<1.6 T
4.8 uH<A1<6 uH
−1<H<+1 (A/cm)
where:
ui is the initial magnetic permeability,
Bsat is the magnetic saturation induction expressed in teslas (T),
Al is the inductance factor, and
H is the magnetic excitation
said winding is formed by a copper sheet with two planar winding turns providing a 2:1 transformation ratio in relation to said power line ( 2 );
electrical insulation is arranged between said copper sheet and the ring-shaped magnetic core ( 10 );
said opposite planar faces ( 11 A, 11 B, 12 A, 12 B) of the ring-shaped magnetic core segments (A, B) are cut with mirror finish polishing; and
the assembly of the ring-shaped magnetic core ( 10 ) and the winding is surrounded by an overmolded thermoplastic shell with a dielectric strength of 190 Kv/cm;
such that the device is configured for operating with low-frequency data signals between 50 kHz and 600 kHz with attenuation of 8 to 10 dB in a 100 to 250 kHz band and of 4 to 6 dB in a 250 to 600 kHz band.
2. The device according to claim 1 , characterized in that the outer diameter of the device is equal to or less than 100 mm.
3. The device according to claim 1 , characterized in that the thickness of the wall of each segment of the ring-shaped magnetic core is comprised between 20 and 30 mm.
4. The device according to claim 1 , characterized in that the thickness of the wall of said thermoplastic shell on the inner face surrounding the power line ( 2 ) is about 4 mm.
5. The device according to claim 1 , characterized in that said copper sheet has a width comprised between 8 mm and 12 mm.
6. The device according to claim 1 , characterized in that it integrates waterproofing means ( 13 ) making said separating gap ( 11 and 12 ), formed by the opposed positioning of two end planar faces ( 11 A, 11 B) and ( 12 A, 12 B) of each ring-shaped core segment (A, B) when they are opposite one another, impermeable.
7. The device according to claim 6 , characterized in that said waterproofing means ( 13 ) comprise gaskets continuously surrounding the edges of said two opposite planar faces ( 11 A, 11 B) and ( 12 A, 12 B) of the ring-shaped core segments (A, B).
8. The device according to claim 1 , characterized in that said connector ( 30 ) for a coaxial cable is waterproofed.
9. The device according to claim 1 , characterized by integrating waterproofing means ( 13 ) making said separating gaps ( 11 and 12 ), formed by the opposed positioning of two end planar faces ( 11 A, 11 B) and ( 12 A, 12 B) of each ring-shaped core segment (A, B) when they are opposite one another, impermeable, and in that said connector ( 30 ) for a coaxial cable is waterproofed with resistance to immersion in a liquid.
10. The device according to claim 1 , characterized in that said thermoplastic shell overmolded on the ring-shaped magnetic core ( 10 ) and winding is obtained by a charged UV-resistant polyamide.
11. The device according to claim 1 , characterized in that each of said end planar faces ( 11 A, 11 B) and ( 12 A, 12 B) of the two ring-shaped core segments (A, B) incorporate an overlaid tape ( 20 ) made of an electrical insulation material further providing a damping effect when said faces are opposite and very close to one another.
12. The device according to claim 11 , characterized in that said tape ( 20 ) made of an electrical insulation material is obtained from a sheet of polyester.
13. The device according to claim 1 , characterized by further comprising two half-round shaped partitions ( 40 ) opposite and spaced from one another, attached to one of the ring-shaped magnetic core segments (A or B) such that when said two segments close around the opening ( 15 ), they cover the inner edges of the separating gaps ( 11 and 12 ) for application in bare cable power lines.
14. The device according to claim 13 , characterized in that said half-round shaped partitions ( 40 ) are longer than the ring-shaped magnetic core ( 10 ) and extend in cantilever beyond the two faces of said magnetic core segments (A, B), perpendicular to the power line ( 2 ).