From a usage point of view, power plant generators have been greatly improved. They were originally air-cooled and purely air-cooled. Current generators include water cooling, single water internal cooling and double water internal cooling, as well as water-hydrogen cooling (stator water cooling, rotor and air gap hydrogen cooling), and those over 300,000 kilowatts are all water-hydrogen cooled. They all have their own advantages and disadvantages: air cooling is bulky and expensive, and the system is simple. Water-cooled hydrogen cooling is small in size, inexpensive, complex in terms of system, has many fault points, and is inconvenient to use. The excitation system has also been greatly improved. It turns out that the exciter is driven coaxially with two and threeis excitement levels, and the brushes tend to catch fire and wear out. It is now a statically excited silicon rectifier, with no sparking or wear. etc.
A ground fault at one point on the rotor does not cause damage to the generator, but a second ground point occurs one after the other. That is, when the rotor is grounded at two points, a considerable fault. the current passes through the fault point and burns the rotor body. Increasing the current in the field winding can lead to burns due to overheating, because part of the winding is short-circuited, the air gap flux is unbalanced, causing vibration and even magnetization of the body . shaft and turbine. The consequences of a two-point earth fault are serious