Safety instrumented process control apparatus and methods

摘要

Example apparatus and methods to remove power from a field device are disclosed. An example apparatus includes a first switch to control power to the field device, and a second switch comprising a first gate and a second gate. The second gate is electrically coupled in parallel to the first gate, and the second switch is electrically coupled in series to the first switch. The example apparatus also includes a first diagnostics controller to control the first and second gates, a first processor to control the first switch, a third switch to control power to the field device, and a fourth switch comprising a third gate and a fourth gate. The fourth gate is electrically coupled in parallel to the third gate, and the fourth switch is electrically coupled in series to the third switch. The example apparatus also includes a second processor to control the third switch, and a second diagnostics controller to control the third and fourth gates.

主权项

1. An apparatus comprising:
a first switch to control power to a field device; a second switch comprising a first gate and a second gate, the second gate electrically coupled in parallel to the first gate, wherein the second switch is to provide parallel current paths through the second switch, the first and second switches defining a current path between a source of the power and the field device; a first diagnostic controller to control the first and second gates independently of one another to verify a first redundant control of the field device; a first processor to control the first switch; a third switch to control power to the field device; a fourth switch comprising a third gate and a fourth gate, the fourth gate being electrically coupled in parallel to the third gate, wherein the fourth switch is to provide parallel current paths through the fourth switch, the third and fourth switches defining a current path between the source of the power and the field device; a second processor to control the third switch; and a second diagnostic controller to control the third and fourth gates independently of one another to verify a second redundant control of the field device.