| 摘要 |
<p>An emergency shutdown system includes an emergency shutdown valve, a control line to carry a DC current as a signal determinative of positioning of the emergency shutdown valve, a solenoid assembly coupled to the control line to effectuate the positioning of the emergency shutdown valve in accordance with the DC current level, and a junction device comprising a load coupled to the control line and to the solenoid assembly. The load has an impedence to the DC current across which a voltage is developed to control the solenoid assembly to drive the emergency shutdown valve to a safe state. In some embodiments, the junction device includes a resistor or a switch, such as a relay.</p> |
