Introduction
When there are multiple installation conditions along the length of a cable run, each physical length of the same laying type must be multiplied by the relevant coefficients following the same rules as above.
The sum of the various results must be less than ETL (Transparent Factory).
Example 4: New laying plan for 30m of Transparent Factory cable
The signal cable in example 3 is laid along 10m according to the laying type above; the remaining 20m are laid 10 cm away from the first one, in a separate duct from the power cable, but placed.
Calculation table
Length |
Ki coefficients |
Calculations |
Results |
|---|---|---|---|
10 m |
K0 (=12) et K50 (=2) |
10 m x 24 |
240 m |
20 m |
K10 (=2) et K50 (=2) |
20 m X 4 |
80 m |
Total (30 m) |
240 m + 80 m |
320 m |
|
As the resulting 320m is now less than ETL = 400m, the 30 m installed length will comply with EMC requirements.
Example 5: Laying plan for a 1000m FIP cable
The documentation for the system shows that the first limit is observed, provided only if main cable (150 ohms single pair large gage) is used.
The ETL value for this technology is 2000 m.
Let us assume that the 2 optimum conditions are observed for 700m and that for the rest of the length the power duct is:
filled to more than 50%,
and only 10cm away from the signal duct.
Calculation table
Length |
Ki coefficients |
Calculations |
Results |
|---|---|---|---|
700 m |
no |
700 m |
|
300 m |
K50 (=2) et K10 (=2) |
300 m X 4 |
1.200 m |
Total (1.000 m) |
700 m +1.200 m |
1.900 m |
|
As the result 1900m is less than ETL = 2000m, the installed length will comply with EMC requirements and only the previous contingency remains (no small gage pair).