The six categories of turbine instrumentation are1
Supervisory instrumentation
Efficiency instrumentation
Auxiliary system instrumentation
Condition-monitoring instrumentation
Instrumentation associated with protection and control equipment
Instrumentation to provide postincident records
The most important of these six categories are supervisory and efficiency instrumentation. This is due to the significant role they play in monitoring plant safety and power production.
The supervisory instruments are required continuously to determine the condition of the main rotating and stationary components. The main functions of supervisory instruments include the following:
To ensure safe operation within acceptable limits.
To provide advanced warning of deterioration in the performance of the turbine generator. Maintenance or temporary restriction in the operating mode may be required. The measured parameters include the following:
Rotor axial position. These measurements provide the relative axial movement of the rotor. They are used to ensure that clearance margins are maintained under all operating conditions. These measurements are normally taken on each cylinder of the machine.
Cylinder expansions. These measurements provide the relative radial movement between the rotors and the stators. They are used to ensure that radial clearance margins are maintained under all operating conditions. These measurements are normally taken on each cylinder of the machine.
Bearing pedestal vibrations. These measurements are taken at each bearing. They continuously monitor the dynamic behavior of the machine.
Shaft eccentricity. The radial excursion of the rotor (peak-to-peak) relative to the stationary parts is measured on...
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