1 Subject Content and Application Scope
This standard specifies the humid heat test method, technical requirements and inspection rules of the rotating electrical machine for service in general environmental condition.
This standard is applicable to all kinds of rotating electrical machines (except mini-type control machine, hereinafter referred to as electrical machine). According to GB 755, the electrical machines in the environment where the relative humidity of service environment is: the average relative humidity in the wettest months is 90% and the average minimal temperature in that month is not higher than 25℃ shall meet the requirements of this standard.
2 Normative References
GB 755 "General Requirements for Rotating Electrical Machines"
GB 2423.3 "Basic Environmental Testing Procedures for Electric and Electronic Products--Test Ca: Damp Heat, Steady State"
GB 2423.4 "Basic Environmental Testing Procedures for Electric and Electronic Products --Test Db: Damp Heat, Cyclic"
GB 5170.5 "Inspection Methods for Basic Parameters of Environmental Testing Equipments for Electric and Electronic Products-Constant Damp Heat Testing Equipments"
GB 5170.6 "Inspection Methods for Basic Parameters of Environmental Testing Equipments for Electric and Electronic Products-Cyclic Damp Heat Testing Equipments"
3 Test Methods
3.1 Preparation before the test
3.1.1 Test facilities and equipments
Damp heat test chamber (box) shall meet the requirements of GB 5170.6 or GB 5170.5.
The voltage grade of tramegger measuring the insulation resistance shall be in accordance with those specified in Table 1. When the spare parts are tested by using tramegger, if it is difficult to judge whether the spare parts are qualified or not due to the limit of measuring range, then the high insulation resistance tester shall be adopted for measuring.
Table 1 V
Rated voltage of electrical machine Operating voltage of tramegger
≤36
>36~500
>500~1000
>1000 250
500
1000
2500
3.1.2 Sample requirements
When the spare parts of the large electrical machine are tested, the measurement electrodes for high tension stator coil and DC electrical machine compensation coil shall adopt the aluminium foils, the coil with slot insulation and dipping paint shall be made into simulated slot and the aluminium foil electrode length shall be identical with the actual core length generally. If limited by the product dimension, the smaller simulating units with identical material, insulation structure and process may be adopted for the test.
3.1.3 Sample pretreatment conditions
Before damp heat test, the sample shall be placed in the damp heat test chamber (box) for preheating treatment at 25℃~35℃ for not less than 8h since the temperature of the chamber (box) reaches 25℃.
3.2 Damp heat test method
Generally, the damp heat test shall be carried out according to the 40℃ cyclic damp heat test method, the conditions of every period shall be in accordance with GB 2423.4, the provisions on 40℃ cyclic damp heat test are shown in Figure 1 and the test shall be carried out for 6 periods.
The damp heat test of electrical machine shall adopt the sample with indistinct respiration effect, and the relative humidity in temperature drop stage may not be less than 85% (shown in dotted lines).
If necessary, the products of relevant specialties may also be carried out with the damp heat test according to GB 2423.3 and the constant damp heat test method under the conditions of 40±2℃, 90%~95% and 48h.
