320
•
Use in Hazardous Environments
Classification
Meeting CENELEC and IEC
WAGO-I/O-SYSTEM
750
BACnet/IP Controller
9.3.4 Temperature
Classes
The maximum surface temperature for electrical components of device 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 permissible surface temperature for all ignition
protection types, the electrical components are subdivided into temperature
classes, as far as electrical components of device group II are concerned.
The maximum surface temperature of any electrical equipment must always be
less than the ignition temperature of the explosive atmosphere occurring in its
area of use.
It goes without saying that an equipment fulfilling the requirements of tem-
perature class T3 is also suitable for use in explosive atmospheres of tempera-
ture classes T1 and T2.
Tab. 9-3: Temperature classes
Temperature Classes
Maximum permissible
surface temperature of
the equipment
Ignition Temperature
of the Combustible Materials
T1
450 °C
> 450 °C
T2
300 °C
> 300 °C to 450 °C
T3
200 °C
> 200 °C to 300 °C
T4
135 °C
> 135 °C to 200 °C
T5
100 °C
>100 °C to 135 °C
T6
85 °C
> 85 °C to 100 °C
The following table represents the division and attributes of the materials to
the temperature classes and material groups in percent:
Tab. 9-4: 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
*
85.2 %
13.8 %
1.0 %
501
*
Number of classified materials
