![]() A reduction in the purity of the hydrogen coolant increases windage losses in the turbine due to the associated increase in viscosity and drag. These losses can be significant due to the rotors high rotational speed. Hydrogen has very low viscosity, a favorable property for reducing drag losses in the rotor. The second (0-100% H 2) and third (0-100% CO 2) measuring ranges allow safe opening of the turbines for maintenance. The first range (80-100% H 2) to monitor the hydrogen purity during normal operation. The working pressure is up to 6 bar.Īn on-line thermal conductivity detector (TCD) analyzer is used with three measuring ranges. ![]() Hydrogen gas is circulated in a closed loop to remove heat from the active parts then it is cooled by gas-to-water heat exchangers on the stator frame. In such cases, eddy currents are generated in the rotor, and the resulting Joule heating could in extreme cases destroy the generator. #Helium electric generator generatorThe rotor usually contains caps or cage made of nonmagnetic material its role is to provide a low impedance path for eddy currents which occur when the three phases of the generator are unevenly loaded. ![]() The amount of excitation power ranges between 0.5-3% of the generator output power. The excitation current on larger generators can reach 10 kA. Modern generators have the excitation generator on the same shaft as the turbine and main generator the diodes needed are located directly on the rotor. Older generators used dynamos and slip rings for DC injection to the rotor, but the moving mechanical contacts were subject to wear. The turbogenerator also contains a smaller generator producing direct current excitation power for the rotor coil. Two-pole machines typically operate at 3000 rpm for 50 Hz and 3600 rpm for 60 Hz systems, half of that for four-pole machines. To control the centrifugal forces at high rotational speeds, the rotor diameter typically does not exceed 1.25 meters the required large size of the coils is achieved by their length and so the generator is mounted horizontally. The generated power is sent to a nearby step-up transformer, where it is converted to the electric power transmission line voltage (typically between 1 kV). For generators up to 40 MVA, the voltage is 6.3 kV large generators with power above 1000 MW generate voltages up to 27 kV voltages between 2.3-30 kV are used depending on the size of the generator. The generators produce high voltage the choice of voltage depends on the tradeoff between demands of electrical insulation and handling high electric current. For the highest power generators, up to 1800 MW, hydrogen and water cooling is used the rotor is hydrogen-cooled, the stator windings are made of hollow copper tubes cooled by water circulating through them. Between 60-450 MW hydrogen cooling is employed. For generators up to 60 MW, air cooling can be used. Generally, three cooling approaches are used. K) was considered as coolant as well, however its high cost hinders its adoption despite its non-flammability.Helium with a thermal-conductivity of 0.142 W/(m A hydrogen-cooled generator can be significantly smaller, and therefore less expensive, than an air-cooled one. Another advantage of hydrogen is its easy detection by hydrogen sensors. K)) of all gases it is 7-10 times better at cooling than air. ![]() The use of gaseous hydrogen as a coolant is based on its properties, namely low density, high specific heat, and the highest thermal conductivity (at 0.168 W/(m Based on the air-cooled turbo generator, gaseous hydrogen first went into service as the coolant in a hydrogen-cooled turbo generator in October 1937, at the Dayton Power & Light Co. ![]()
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