Electronically controllable and testable turbine trip system

Abstract

A tripping control system for use with, for example, turbines, includes a block circuit having two or more redundant blocking valves disposed or connected in series within a pressure supply line to block the supply of hydraulic fluid within the pressure supply line and a bleed circuit having two or more bleed valves connected in parallel between the pressure supply line and a return or dump line to bleed to the hydraulic fluid from the pressure supply line. The blocking valves and the bleed valves are actuated by one or more control valves under the control of a process or safety controller which trips the turbine by first performing a bleed function using the bleed valves, which then causes the block function to automatically actuate. Pressure sensors disposed at various locations in the tripping control system provide feedback to the controller to enable the controller to test each of the block and bleed valves individually, during operation of the turbine, without causing an actual trip of the turbine. The tripping control system thereby provides reliable trip operation during a trip by providing redundant block and bleed functionality in combination with enabling the individual components of the block and bleed circuits to be tested while the turbine is online and operating but without preventing the turbine from being tripped, if necessary, during the test.