The method of controlling these is dependent on the type and size of the turbine and the steam conditions for which it is designed. The main requirement of the automatic run-up and loading system is to limit the thermal stresses within the turbine rotor and valve chests during changes of speedĪnd load. The operator must then decide whether there are sufficent desk indications to permit progress, or to hold at a safe condition whilst a repair is effected, or to shut down the turbne. The turbine governor will provide a limitation on the rate-of-change of speed or load, but this will not necessarily be safe, particularly if a cold start is in progress.
SIEMENS GENERATOR STOPPED ALARM GOVERNOR FAULT MANUAL
If further signals fail, only manual control may be possible. If several minor input signals are lost or one of a duplicate pair of major signals, automatic control may be restricted such that there is only a fixed safe acceleration rate (if in run-up mode) or fixed safe loading rate (if on load control). The failed transducers are identified to the operator. Thus, if one of the minor input signals is lost, fully automatic operation may still be possible. Most inputs are either duplicated by 'master' and 'check' transducers at the same measuring point, or there is functional duplication built into the system because of measurements made at entirely different measuring points (e.g., separate measurement of inlet steam pressure in left-hand and right-hand steam chests). A digital state signal will indicate that each of these conditions or prestart interlocks has been satisfied.īecause of the large number of plant-mounted transducers providing inputs, careful consideration is given at the design stage to provide enough redundancy to permit fully automatic run-up and loading with high availability. Thus lubricating oil, main and auxiliary CW systems, etc., will have previously been brought into service. The scope of the system described here assumes that separate operator actions or sequencing systems bring all the auxiliary systems necessary for the safe operation of the turbine to a satisfactory state of readiness. The inputs to system depend on the degree of sophistication, in the most comprehensive case they would be as shown. The inputs and outputs are shown on Fig 2.10. Some outputs of digital state signals provide interlock or initiation signals to the governor and auto-synchroniser, whilst others provide indications to the operator.
The primary output of a typical system is to the basic speed governor, either to increment the speeder gear or to the governor in such a way that failure of the output signal gives a similarly rate-limited change in demand. Sophisticated schemes can be provided where the rate of run-up or loading is faster and less stressful for the machine than a human operator could reasonably achieve. To run-up and subsequently load the turbine in a safe and consistent manner.To assist the operator in making the complex sequence of checks necessary prior to and during start-up.Automatic run-up and loading systems are provided for two main reasons:
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