JB/T 4375-2013Environmental conditions of electric products in indoor and outdoor corrosive location (English PDF)

3.1

The weather protection types used in this standard shall be as specified in GB/T 4797.1.

3.2

When designing the corrosion resistant electric products, attention shall be paid to the fact that when two or more environmental parameters act in combination, the impact on the products will be increased. It is especially significant when high relative humidity acts in combination with chemically active substances or mechanically active substances. Attention shall also be paid to the impact of other environmental factors, such as heat dissipation sources and special production processes, which occur in certain locations.

3.3

If the environmental condition grades specified in this standard cannot meet the extreme special environmental conditions, other grades specified in GB/T 4796 may be adopted through negotiation between the manufacturer and the user.

4.1

The environmental conditions are classified into the following six categories: climatic conditions (K), special climatic conditions (Z), biological conditions (B), chemically active substance conditions (C), mechanically active substance conditions (S) and mechanical conditions (M).

4.2

The severity of environmental conditions for corrosion resistant electric products shall be selected from Table 1. Grades marked with larger numbers usually include grades marked with smaller numbers (with the exception of special climatic conditions (Z)).

4.3

For the purpose of this standard, the environmental condition grade with the lowest severity that can meet the operating requirements of the products shall be selected.

4.4

For the environmental condition grades (e.g. codes 3K×, 3Z×, 3C× and 4K×, 4Z×, 4C×, etc.) specified in this standard, "3” indicates the weather-protected locations while "4" indicates the non-weather-protected locations.

4.5

The environmental condition grades for climatic conditions are shown in Tables 2 to 5.

——See Tables 2 and 3 for the environmental parameters for different grades of climatic and environmental conditions. The environmental parameters listed in the table are multi-year averages of the maximum value in each year;

——See Tables 4 and 5 for the different grades of special climatic and environmental conditions.