Filter
Top Products
4 • Application in Explosive Environments
Classification meeting CENELEC and IEC
WAGO-I/O-SYSTEM 750
Modular I/O-System
Ex-1.3.4 Temperature classes
The maximum surface temperature for electrical components of explosion
protection group I is 150 °C (danger due to coal dust deposits) or 450 °C (if
there is no danger of coal dust deposit).
In line with the maximum surface temperature for all ignition protection types,
the electrical components are subdivided into temperature classes, as far as
electrical components of explosion protection group II are concerned. Here the
temperatures refer to a surrounding temperature of 40 °C for operation and
testing of the electrical components. The lowest ignition temperature of the
existing explosive atmosphere must be higher than the maximum surface
temperature.
Temperature classes Maximum surface
temperature
Ignition temperature
of the combustible materials
T1 450 °C > 450 °C
T2 300 °C > 300 °C ≤ 450 °C
T3 200 °C > 200 °C ≤ 300 °C
T4 135 °C > 135 °C ≤ 200 °C
T5 100 °C >100 °C ≤ 135 °C
T6 85°C > 85 °C ≤ 100 °C
The following table represents the division and attribution of the materials to
the temperature classes and material groups in percent:
Temperature classes
T1 T2 T3 T4 T5 T6 Total
*
26.6 % 42.8 % 25.5 %
94.9 % 4.9 % 0 % 0.2 % 432
Explosion group
IIA IIB IIC Total
*
80.2 % 18.1 % 0.7 % 436
*
Number of classified materials
Ex-1.3.5 Types of ignition protection
Ignition protection defines the special measures to be taken for electrical
components in order to prevent the ignition of surrounding explosive
atmospheres. For this reason a differentiation is made between the following
types of ignition protection: