The basis for not drying the rotor without drying the rotor is whether the gap between the stator and rotor can wear the heating coil. After consulting the drawing and the gap between the actual measuring element and the rotor is 40mm, it is possible to wear the heating excitation coil. This saves time by eliminating the need to pump and wear the rotor. At the beginning, the Russian experts insisted on extracting the rotor for heating and drying. However, after many discussions with Russian experts and the chief engineer of the generator factory, the Russian side believed that this method proposed by our company was both feasible and advanced, so it agreed.
Eddy Current Vacuum Drying The general drying method for steam turbine generators is the static iron loss drying method and the direct current coil heating method. A brief introduction to the method of heating the stator core with a magnetized winding is given. The method of heating the stator core with a magnetized winding is derived from the stator core loss test. An insulated wire is passed through the stator and the rotor gap to form a coil, and the coil is sinusoidal alternating current. The heating and drying of the stator core can be realized, which is based on the iron loss of the iron core by the sinusoidal alternating current to heat the iron core. Generally, the steam turbine generator can not be vacuumed, but the structural characteristics of the water-oil-cooled steam turbine generator, the stator winding and the iron core are sealed by the insulation, and the oil pressure test of the manufacturer is not leaked for 24 hours. Therefore, it is permissible to evacuate during the drying process. This can greatly shorten the drying time.
In order to increase the temperature rise rate and the heating effect of the stator winding, a direct current is applied to the stator winding. The stator windings are connected in series in three phases, and the current of 500A is used to obtain a heating power of 10 KW, which is provided by a DC welding machine. Since the DC heating is provided by the electric welder, it cannot be continuously heated, and the safety of the welding machine is premised. Preparation for heating and drying In order to carry out the drying smoothly, the following preparations should be made before heating. Use a rock wool felt to heat the generator casing three layers to prevent heat dissipation. Prepare the following instrumentation multiplexed clamp ammeter (measured AC current value). Each of the 500V and 2500V megohmmeters has one AC and DC 0-450V voltmeter. Five alcohol thermometers (one at room temperature).
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