loop inductance of 4 core x 0.5 sq.mm braid shielded cable

We have problem in controlling the loop inductance below 0.76 micro henry/mt for a 4 x 0.5 sq.mm with XLPE insulation and tinned copper wire shield. With different parameters of shield, we could never go below 0.86 micro henry.
Can somebody suggest a solution?

Is this cable built as a coaxial cable? If so, here is an analysis.

The insulation has no effect on the inductance. The inductance is affected by the ratio of the shield to inner conductor. Your coaxial cable can be analyzed as if it has vacuum as the dielectric.

The inductance of a transmission line is:* L = td Z*, where td is time delay and Z is ohms

solving for Z = L/td

The time delay per meter is 3.33 ns/m

Z = 0.86uH/3.33ns = 258 ohms, the "intrinsic" impedance of your cable

Impedance of a vacuum dielectric coaxial cable is *Z = 138LOG(D/d)*

solving for D/d = 10^(Z/138) = 10^(258/138) = 74

This tells us that the shield diameter is 74mm with the inner conductor being 1 mm.

From this I suspect your cable is not coaxial, or it has a huge shield diameter, or your inductance measurement is in error.

Dear David

Thanks for your reply.

Let me clarify that the cable under issue is NOT a coaxial cable. It is a transducer cable
for load cell application with following specs.

Conductor , stranded tinned copper of 0.5 sq.mm and, Resistance 36 ohms/km
Insulation XLPE, dielectric constant of 2.3, thickness 0.4 mm, ins. od 1.8 mm
4 cores twisted and overall braid shielded , shield resistance 11 ohms/km
Diameter under shield- 4.3 mm, diameter over shield- 5.2 mm,
Cable sheath of PU , diameter 7.4 mm
The cable electrical parameters : Core to core capacitance < 55 pf/mt( symmetrical)
Loop inductance < 0.76 micro H /mt

I am not getting the loop inductance within specified value. What should be the shield
parameter or any other factor to achieve this?