English to Greek Tech/Engineering Mechanics / Mech Engineering

Steam turbine
Pressure ratio trip device

If steam flows drop below a certain level the pressure ratio between the steam pressure upstream of the HP blading and the pressure in cold reheat line before nonreturn valve can result in violation of a minimum permissible level and thus pose a risk of damage to the HP blading.
The protection circuit is linked to a limit control device, which try to prevent the final trip actuation.
When the HP-Proportion Pressure rises towards trip value the main steam control valves open a little bit more and the reheat control valves close a little bit (Valve-Trimmimg).

The relationship given by the limit pressure characteristic determines the activation level.
The trip signals are connected in a 2-out-of-3 logic.