1. The voltage is too high during operation and the insulation is broken
2 Long-term overload causes the stator coil temperature to increase and the insulation to age significantly
4. Most 500 kW units have a low-voltage line voltage of 0.4 kV, a long-term operating voltage of 0.38 ~ 0.42 kV, and a rated current of 902 A. Generally speaking, they do not can only work beyond that. the nominal value for a short period.
Because when the generator operates, the leakage magnetic field at the end of the stator winding turns equalement against the stator at a synchronous speed. Part of the leakage magnetic field passes through the gap at the end of the stator. the stator winding, the rotor protection ring, the air trap and the iron core at the end of the stator form a magnetic circuit, so that eddy currents are generated on the plane of the iron core at the end of the stator and heat is generated. In addition, the excitation winding is close to the guard ring, so its leakage magnetic field is mainly closed through the guard ring when the phase is running. When the excitation current decreases, the leakage magnetic field at the end of the excitation winding is weakened. thus the saturation level of the guard ring decreases, which reduces the magnetic group of the magnetic circuit through which the leakage field passes at the end of the stator, thereby increasing the leakage magnetic field at the end of the stator .Iron shoots are enlarged. , causing significant heating of the iron core at the end of the stator.
The generator is mainly composed of stator, rotor, end cover, brush, frame and bearings. The stator consists of a machine base, a stator core, a wire winding and other structural parts that secure these parts. The rotor consists of the rotor core, rotor magnetic poles (with magnetic yoke and magnetic pole windings), slip rings (also called copper rings and slip rings), fans and rotating shafts. The stator and rotor of the generator are connected and assembled through the bearing, base and end cover, so that the rotor can rotate in the stator. A certain excitation current passes through the slip ring to make the rotor a rotating magnetic field. and the stator coil moves tocutting the magnetic lines of force, thereby generating an induced electrical potential, which is drawn through the terminal block and connected in the circuit to generate a current. Due to a broken connection between the brush and the rotor, the rotor rotates in a certain direction and generates alternating current. Therefore, alternating current in household and other circuits is called alternating current.