IEC 60034-11-2004 pdf – Rotating electrical machines – Part 11: Thermal protection

IEC 60034-11-2004 pdf – Rotating electrical machines – Part 11: Thermal protection.
1 Scope 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 machines manufactured in accordance with IEC 60034-12 with the voltage limits specified in IEC 60034-12. The protection of bearings and other mechanical parts is not included. NOTE 1 Although temperature values given in this standard 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 referenced documents are indispensable for the application 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 60034-1:2004, Rotating electrical machines – Part 1: Rating and performance IEC 60034-12:2002, Rotating electrical machines – Part 12: Starting performance of single- speed three-phase cage induction motors 3 Terms and definitions For the purposes of this part of IEC 60034, the following terms and definitions apply. 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 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 3.7 maximum temperature after tripping the maximum value of the temperature that is reached by the protected part of the machine during the period which follows tripping by the thermal protection system 3.8 direct thermal protection form of protection where the part of the machine in which the thermal detector(s) or thermal protector(s) are incorporated is the part for which protection is being provided 3.9 indirect thermal protection form of protection where the part of the machine in which the thermal detector(s) or thermal protector(s) are incorporated is not the part for which protection is being provided 4 Thermal protection limits Machines shall be capable of operating at rated output and at all operating conditions according to IEC 60034-1 without activation of the thermal protection device. The thermal protection device shall limit the winding temperature in accordance with Clauses 5 or 6.
7 Restart after tripping Before restarting a machine that has tripped, an investigation shall be made to try to identify the cause of the operation of the machine protection. When attempting to restart the machine, account shall be taken of the conditions stated in 6.3 or 8.3 of IEC 60034-12. The methods of protection included in this standard only protects rotor windings indirectly. For large motors (particularly 2 pole motors) and for motors starting large inertia loads, special attention needs to be given to rotor heating both when starting and especially after a “trip” has occurred. NOTE The provision of the facility to enable machines to be automatically restarted after tripping is a matter for special agreement taking full account of all safety implications. 8 Type tests 8.1 General Type tests are to verify the compliance of a thermal protection system with the requirements of this standard. Tests shall be made on a machine which is representative of the machine type. The proposed thermal protection system shall be installed. Temperature sensors used for testing shall be located in positions representative of the location of the thermal detectors used by the thermal protection system.