초록 ▼

An emergency shutdown system for a process control system includes an emergency shutdown (ESD) valve and an associated valve actuator. An emergency shutdown (ESD) controller provides output signals to the ESD valve in the event of a failure in the process control system. A solenoid valve responds to

An emergency shutdown system for a process control system includes an emergency shutdown (ESD) valve and an associated valve actuator. An emergency shutdown (ESD) controller provides output signals to the ESD valve in the event of a failure in the process control system. A solenoid valve responds to the ESD controller to vent the actuator to a fail state. A digital valve controller (DVC) test strokes the ESD valve. An impedance booster device enables the dc powering of the solenoid valve and the DVC over a two wire line while still permitting digital communication over the same two wire line.

대표청구항 ▼

[ What is claimed is:] [8.] An emergency shutdown system for a process control system comprising:an emergency shutdown valve and associated valve actuator located within a desired portion of the process control system;an emergency shutdown controller providing output signals for commanding the opera

[ What is claimed is:] [8.] An emergency shutdown system for a process control system comprising:an emergency shutdown valve and associated valve actuator located within a desired portion of the process control system;an emergency shutdown controller providing output signals for commanding the operation of the shutdown valve in response to sensing of a failure event in the process control system;a solenoid valve coupled to the shutdown valve actuator and responsive to the shutdown controller output signals for venting the actuator to a fail state;digital valve controller means for testing the operability of the emergency shutdown valve, the digital valve controller means including a pressure output coupled to the shutdown valve actuator for ramping the shutdown valve from a normal position to a test position and returning to the normal position;a two-wire line connected at one end to the emergency shutdown controller, and at the opposite end to the solenoid valve and the digital valve controller means, the solenoid valve and the digital valve controller means being coupled in parallel across the two-wire line; anda digital communications device coupled to the two-wire line, wherein the digital valve controller means is adapted to receive digital control signals from the digital communications device, and responsively ramp the shutdown valve from the normal position to the test position and return to the normal position.