IEC 60079-14:2013/ISH1:2017

– 2 – IEC 60079-14:2013/ISH1:2017
 IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
IEC 60079-14
Edition 5.0  2013-11
EXPLOSIVE ATMOSPHERES –
Part 14: Electrical installations design, selection and erection

INTERPRETATION SHEET 1
This interpretation sheet has been prepared by subcommittee 31J: Classification of hazardous
areas and installation requirements, of IEC technical committee 31: Equipment for explosive
atmospheres.
The text of this interpretation sheet is based on the following documents:
ISH Report on voting
31J/268/ISH 31J/270/RVD
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.
___________
INTERPRETATION SHEET
Interpretation sheet for IEC 60079-14:2013, Explosive atmospheres – Part 14: Electrical
installations design, selection and erection
Following decision No 1 of the SC 31J meeting in Frankfurt in 2016, the issuing of an
Interpretation Sheet for IEC 60079-14:2013 was requested, in order to clarify the issues
relating to the installation of the converter supply or reduced voltage starting of electric
motors.
Details of interpretation:
Interpretation of sub clauses 11.2.1 b), 11.2.2 b), 11.3.5 b), 11.4.1 b) 11.4.2 b), 11.5.1 b),
11.5.2 b), 11.6.1 b) and 11.6.2 b) for Motors with converter supply or reduced voltage
starting
The motor has not been type-tested for this duty as a unit in association with the converter.
In this case, means (or equipment) for direct temperature control by embedded temperature
sensors specified in the motor documentation or other effective measures for limiting the
surface temperature of the motor housing shall be provided. The effectiveness of the
temperature control shall take into consideration power, speed range, torque and frequency
for the duty required and shall be verified and documented. The action of the protective
device shall cause the motor to be electrically disconnected.”

ICS 26.260.20
IEC 60079-14:2013-11/ISH1:2017-02(en-fr)

 IEC 2017
Question
Is physical disconnection, such as a switch (circuit breaker) or contactor, required to
accomplish the intent of this requirement ?
Interpretation
The intention of this requirement is to protect the machine from excessive surface
temperatures.
Any action within the control circuit for the motor that accomplishes one of the following
satisfactorily meets the intent of this requirement:
• direct physical disconnection resulting in no output voltage to the motor, or,
• control circuit intervention such as ceasing modulation, resulting in the motor not
operating.
NOTE In this case, voltage to a motor may still exist, but the motor does not operate.

– 4 – IEC 60079-14:2013/ISH1:2017
 IEC 2017
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
IEC 6
...