IEC 60034-11-2020 ROTATING ELECTRICAL MACHINES – Part 11 : Thermal protection.
This part of IEC 60034 specifies requirements relating to the use of thermal protectors and thermal detectors incorporated into the stator windings or placed in other suitable positions in induction machines in order to protect them against serious damage due to thermal overloads. It applies to single-speed three-phase 50 Hz or 60 Hz cage induction motors in accordance with IEC 60034-1 and IEC 60034-1 2 that:
•have a rated voltage up to 1 000 V;
• are intended for direct-on-line or star-delta starting. Not included are:
• direct protection of the rotor winding; the methods of protection only protect rotor windings indirectly; for large motors (particularly 2 pole motors) and for motors starting large inertia loads, special attention is given to rotor heating both when starting and especially after a “trip” has occurred;
• the protection of bearings and other mechanical parts; • the protection methods to be used for particular applications. NOTE 1 Although temperature values given in this document are higher than those specified in IEC 60034-1 , they are not in conflict. NOTE 2 Additional requirements may apply to particular motor types, such as those used in household appliances, or for motors used in explosive atmospheres.
2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60034-1 :201 7, Rotating electrical machines – Part 1: Rating and performance IEC 60034-1 2:201 6, Rotating electrical machines – Part 12: Starting performance of single- speed three-phase cage induction motors
3 Terms and definitions For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 thermal protection protection of windings of a machine against excessive temperature resulting from conditions of overload or loss of cooling
3.2 thermal protection system system for the protection of a machine winding against excessive temperature resulting from conditions of overload or loss of cooling by means of either thermal protector(s) or thermal detector(s)
3.3 thermal detector electrically insulated device that is only sensitive to temperature, capable of initiating a switching function in a protection system when its temperature reaches a predetermined level
3.4 thermal protector electrically insulated device that is sensitive to the temperature of the machine winding which carries machine current, capable of directly switching off the machine when its temperature reaches a predetermined level Note 1 to entry: Some thermal protectors are sensitive to both temperature and current, the combination of which activates the direct switching off of the machine.
3.5 thermal overload with slow variation overload condition or loss of cooling that produces a rise of temperature that is sufficiently slow that the temperature of the thermal protector or detector follows it without appreciable delay
3.6 thermal overload with rapid variation overload condition or loss of cooling that produces a rise of temperature that is too rapid for the temperature of the thermal protector or detector to follow without appreciable delay resulting in a significant temperature difference between the thermal device and the part to be protected.IEC 60034-11 pdf download.