Category: Fault-tolerant management systems
Turbine overspeed protection is one of the critical areas in turbine control, and electronic trip systems can come useful, especially when the rotation speed is at 10 000 rpm or more. The Electronic Overspeed Trip system was designed as an electronic overspeed trip that can be used on new turbines or could be retrofitted into an already installed system. The range of turbines covered is from small industrial to large power industry turbines.
The Electronic Overspeed Trip system measures the rotation frequency and compares it with an emergency setpoint. When a critical speed is reached, the system sends a digital signal to stop the turbine while taking into account its acceleration. That is, if there is acceleration, the Electronic Overspeed Trip recalculates and reduces setpoint so that the rpms don’t overshoot the critical value.
The system is Triple Modular Redundant (TMR) and is built around frequency measurement DA 03 021 custom-designed module with integrated software and frequency generator. The system has three of these modules, and each is connected to one or two frequency sensors.
The power is supplied to the modules and sensors from separate external power sources. Discrete signals are joined together in the external majority circuit according to 2‑out-of-3 principle.
To perform safety checks when the turbine is shut down, the system switches from sensor input to the frequency generator, built into the DA 03 module. The generator provides a set frequency to the measurement circuit, taking into consideration acceleration.
The CPU module in this systems server only to perform diagnostics and to generate tasks for the tests.