Introduction

There are two ways of using the Ki coefficients.

  • To obtain the authorized physical length, you take the ETL and divide it by Ki, (examples 1 and 2 below).

  • On the contrary, when particular physical lengths are imposed necessary, multiply them by Ki and compare the result with the ETL to check that you are compliant with the EMC requirements (examples 3,4, and 5).

Example 1: Transparent Factory links less than 30m

Wiring can then be done in a single metal run (for ETL = 400 m or more).

If the duct is not filled to more than 50% (bear in mind future developments), only the Ko coefficient must then be taken into account, which gives a maximum length of 400 m: 12 = 30 m.

The power cables and shielded digital connections shall be fixed in the corners of the duct as shown in the illustration below:

Example 2: Transparent Factory links up to less than 100m

If length calculated in an installation condition is insufficient (30 m in the first example) it will be necessary to improve the EMC aspect of the configuration.

Vertical separation in the duct avoids mixing incompatible cables. A metal cover on the half duct of the signal cables restricts signal interference.

That's why the coefficient value then goes from 12 (=K0) to only 4 (=K6), which, (with ETL=400) gives the maximum length: ETL / 4 = 100 m.

The EMC conditions to be observed are then:

  • each half duct is filled to 50% max.,

  • the separation is metallic and in contact with the duct along the whole length,

  • the cover is in contact with the separation along the whole length.

NOTE: Bear in mind future developments.

Illustration

Example 3: Plan for laying 30m of Transparent Factory cable

It is planned to lay the cable in a single duct filled to 70% without separation, together with a power cable and an analog cable.

This installation condition, according to the Ki symbols table, is linked to two coefficients: K0 (=12) et K50 (=2); you must therefore multiply the physical length by 2 and by 12.

As the result 720m (30m x12) is greater than ETL=400m, the 30m installed length will not comply with EMC requirements. Example 4 explains a possible solution.