This recommendation applies to industrial furnaces heated indirectly with metallic heating elements (e.g., for heat-treatment, hot-forming, etc.) in which the internal atmosphere is composed of air not intentionally modified.
This recommendation applies to batch chamber, bell, elevator, shaft, carriage, or to furnaces of any similar construction. These furnaces may be constructed either with or without forced air circu-lation.
This recommendation covers furnaces of low and very low voltage categories (below 500 V).
SIS SS IEC 397:1989 history
1989SIS SS IEC 397:1989 Industrial electro-heating equipment — Test methods for batch furnaces with metallic heating resistors