TEFC motors in Class 1, Division 2 - abnormal conditions (ignition source)?

Status
Not open for further replies.

Shells

Member
So I have TEFC motors that meet NEC requirements for use in Class 1, Division 2 location - no arcing/sparking etc.
My question is around the operating surface temperature of the motors.

According to IEEE Std. 841, IEEE Standard for Petroleum and Chemical Industry — Premium-Efficiency, Severe-Duty, Totally Enclosed Fan-Cooled (TEFC) Squirrel Cage Induction Motors — Up to and Including 370kW (500 HP), Section 5.4.2, states: “Temperature Rise ― When operated at rated voltage, frequency, and power, the average temperature rise of any phase of the stator winding shall not exceed 80°C as determined by the winding resistance method. Maximum exposed internal and external surface temperatures shall not exceed 200°C under typical service conditions at 1.0 service factor (SF).” However, this refers to typical conditions so was wondering if it is possible that under electrical fault conditions or mechanical failures, that the max surface temp may increase to the AIT of the area and pose and ignition risk?

Thanks
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Division 1 assumes fuel is commonly present and so must protect from both common and uncommon ignition sources.

Division 2 assumes fuel is not commonly present and so must only protect common ignition sources under normal conditions.

As an interesting observation for motors see Section 500.8(B)(5).
 
Status
Not open for further replies.
Top