General Description of Large- and Medium Scale High-speed Electrical Machines

1. Our company develops the special series of large- and medium-scale high-speed electrical machines after we imported the advanced technology from multi-company of foreign countries.
2. Importing technology of the design and manufacture of large-scale electrical machines from Westinghouse of USA.
3. Importing technology of the design and manufacture from ABB of Switzerland
4. Importing technology of the design and manufacture of electrical machines from Germany AEG
5. Importing technology of the design and manufacture of spherical surface sliding bearing from Germany RENK
6. Calculation on Electromagnetism Design
7. We imported and assimilated the technology of computer software of American Westinghouse, and then combined the conditions of our country and factory. We have developed the MY7864 software by ourselves, through which electromagnetic design was developed.
8. Calculating several key technical data of electric machines ,including efficiency, starting torque, maximum torque, starting current, permitted safe starting time of electrical machine, thermal restriction curve at electrical machine overload time and so on.
9. Using Ansoft, which is for electrical magnetic calculation, to perform finite element analysis of three-dimension electrical magnetic field. By this, the parameters of performance become more precise.
10. Mechanical Calculation
11. With using Ansys to make vibration and deformation calculation of frame and stator cores of electrical machine and frequency spectrum are completely analyzed. These keep harmonic frequencies far off the natural frequency of stator cores
12. Using Ansys software to analyze the thermo and stress characteristics of key parts, like the rotor copper bar and the end ring.

Stator Structure

1. Stator structure and that of the basic Y series products are the same. Both adopt steel plate-welded box style and stator cores are pressed outside. The stator structure has been specially strengthened on the base.
2. Little glue VPI insulation treatment of class F ensures a safe and reliable insulation system.
3. Both electrical machines of level 6KV and 10KV are with perfect discharge-resistant mechanism.
4. Stator cores adopt good magnetic conductibility and low depletion electrical silicon steel belt to reduce the iron loss and to control the vibration and the noise of machines. The lamination factor can be large than 0.97.

Rotor Structure

1. According to the moment of the load, the rotor bar has two types that are trapezoid copper rows and rectangular copper rows.
2. For the copper rows fitting in slot fastening measures, our company has the patent. The measures make sure that the slot bars do not loose.
3. The technology for the connection of copper rows and the end rings adopts the advanced structure and are welded using intermediate-frequency method. Simultaneously, we have additionally installed high strength stainless steel protective rings to ensure the safety when starting and operation.
4. The rotor system has calculated for its mechanical strength, mechanical rigidity and whirling speed. It could endure 1.3 times rated speed.
5. Each rotor must pass through the strict dynamic balance verification and the rotor’s dynamic balance precision is then improved through two procedures- high-speed dynamic balancing and overall dynamic balancing.

Bearing Structure

1. Adopting seated spherical self-aligning sliding bearing
2. With self-aligning function
3. Good support rigidity
4. Easy to adjust
5. Non-shaft end adopts bearing insulation to prevent shaft current
6. Adopting forced oil lubrication.
7. Bearing could be installed with thermo sensor and vibration sensor

Ventilation and Cooling System

• Generally the air-water cooler is used
• Parallel ventilating circuit system with two symmetric
• A fan is installed at each side of the rotor as the air pressure generator.
• There is one way of air to cool down the winding ends and another way of air go through the slot open and into stator core radial air way to cool windings.
• Some of rotor heat disperses from surface through the conduction and the radiation effects and other is carried out by a blast of wind that draft through stator slot opens.
• The hot air from both ends reaches water-air cooler exchange heat and then the air flows to the fans on both ends, forming internal air circulation loop.
• Inlet water temperature of cooler shall be no more than 33。C and pressure 0.2—0.3 Mpa. Water volume is determined by the loss of electrical machine.