Section 1 General Rules

Selection of conductors for heating, economic current density and corona conditions. Permissible continuous currents for bare wires and busbars

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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1.3.22. Permissible continuous currents for bare wires and painted tires are given in table. 1.3.29 - 1.3.35. They are taken based on the permissible heating temperature of + 70 º C at an air temperature of +25 º C.

For hollow aluminum wires of grades PA500 and PA600, the permissible continuous current should be taken:

1.3.23. When rectangular busbars are arranged flat, the currents given in table. 1.3.33, must be reduced by 5% for tires with a stripe width of up to 60 mm and by 8% for tires with a stripe width of more than 60 mm.

1.3.24. When choosing buses with large sections, it is necessary to choose the most economical design solutions in terms of throughput, ensuring the least additional losses from the surface effect and the proximity effect and the best cooling conditions (reducing the number of strips in the package, rational design of the package, using profile tires, etc.) .

Table 1.3.29. Permissible continuous current for bare wires according to GOST 839-80

Table 1.3.30. Permissible continuous current for round and tubular busbars

* The numerator shows loads with alternating current, the denominator shows loads with direct current.

Table 1.3.31. Permissible continuous current for rectangular busbars

* The numerator shows the values ​​of alternating current, the denominator shows the values ​​of direct current.

Table 1.3.32. Permissible continuous current for uninsulated bronze and steel-bronze wires

* Currents are given for bronze with resistivity r₂₀=0,03 Ohm mm²/ m.

Table 1.3.33. Permissible continuous current for bare steel wires

Table 1.3.34. Permissible continuous current for four-lane buses with stripes arranged on the sides of a square ("hollow package")

Table 1.3.35. Permissible continuous current for box-section busbars

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