IEC 60079-31:2022/COR1:2023

© IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
IEC 60079-31 IEC 60079-31
Edition 3.0  2022-01 Édition 3.0  2022-01

EXPLOSIVE ATMOSPHERES – ATMOSPHÈRES EXPLOSIVES –

Part 31: Equipment dust ignition protection by Partie 31: Protection contre l’inflammation de
enclosure "t" poussières par enveloppe "t" relative à
l’appareil
CO RRI G E NDUM 1
Corrections to the French version appear after the English text.
Les corrections à la version française sont données après le texte anglais.

FOREWORD
B) Information about the background of 'Major Technical Changes'
Replace the existing text of C2 with the following new text:
C2 – For Ex Equipment having Level of Protection "ta" only sealed primary cells or batteries
shall be used. A control device shall be provided to prevent overheating of the cell or battery
during normal operation, expected malfunctions, or rare malfunctions. The control device may
also be considered as a thermal protective device or overcurrent protective device. For Ex
Equipment having Level of Protection "tb" and "tc" only sealed cells or batteries shall be used.
A control device shall be provided to prevent overheating of the cell or battery during normal
operation or expected malfunctions (“tb”) or during normal operation (“tc”). The control device
may also be considered as a thermal protective device or overcurrent protective device.
IEC 60079-31:2022-01/COR1:2023-10(en-fr)

– 2 – IEC 60079-31:2022/COR1:2023
© IEC 2023
Table 2 – Overload or malfunction conditions for Level of Protection "tb"
Replace existing Table 2 with the following new table:
Type of Ex Equipment Overload or malfunction conditions
Luminaires (without ballast) None
Luminaires with electro-magnetic ballasts U + 10 % Rectifier effect simulated by diode
n
Luminaires with electronic ballasts As specified for the applicable standard for industrial
equipment
Electric Machines – mains supply connected None
Electric machines – converter connected None if electric machine is evaluated with a specific
converter and a specified duty as described by
IEC 60079-0, or;
If the electric machine is not evaluated with a specific
converter and a specified duty as described by
IEC 60079-0, overload as necessary to confirm that
the required direct thermal protection, normally in the
stator winding, has sufficient margin to be able to
detect excessive temperatures at the bearings,
bearing caps and shaft extensions. The margin may be
determined by test or calculation. In this case, the use
of the thermal protection is made mandatory by
identification of this Specific Condition of Use in the
certificate.
NOTE Direct thermal protection of the bearings is
often appropriate to represent the maximum surface
temperatures of the parts of concern. It has been
found that for some motors, direct thermal protection
of the winding set at 160 °C can be appropriate for
maximum surface temperature T200°C, but this would
still need to be confirmed by test or calculation.
Resistors None
Electromagnets U and worst-case air-gap
n
Other equipment As specified by the applicable standard for industrial
equipment
NOTE For test voltage and current parameters, see the maximum surface temperature requirements in
IEC 60079-0.
----------------------
...