Since the mechanical emergency interrupt requires the actual overspeed test and is tested many times during the service of the turbine, the life of the unit is greatly reduced, and the test itself is dangerous. In addition to the actual overspeed test during the commissioning period or during the acceptance of the turbine, the new design does not require an actual overspeed test after normal operation. When the 350MW unit of Rizhao Power Plant was commissioned, only the channel test was carried out, and the trip setting value was reduced to 3050r/min. After the trip test, the original value was restored. As long as the speed measurement system is reliable, the test will be no problem.
The new design of the security system and lubricating oil system of large steam turbines has been applied in foreign countries for many years. Siemens units have eliminated mechanical emergency breakers 10 years ago. With the increasing application of digital control systems on steam turbines, the maturity of control software and the improvement of reliability of electronic products, China's manufacturing industry has already had the conditions to use this technology, especially with the DEH transformation of large units. The stator grounding protection circuit is correct, the structure is reasonable, and the action is reliable; the protection relay has good performance (but the 3X stator grounding protection LD-8 type relay has high operating power, so the 3X stator grounding protection sensitivity is not high). The 3UO stator grounding protection is set at 10V, and the turn-to-turn protection is set at 4V. The setting is reasonable. According to the test and operation conditions, the daytime protection and 3UO stator grounding protection tripping, 3X stator grounding protection temporarily cast signals.
(Finish)