Abstract: The described methods and systems enable a control panel for a safety valve in a safety system of a process control environment to couple to a safety loop that couples a logic solver to a valve positioner for the safety valve. The control panel may drive a loop current on the safety loop to a desired range, thereby causing the valve positioner to respond by initiating a desired function triggered by the loop current entering the desired range. The desired function may be a trip function, a reset function, or a stroke test function.

Abstract: The present disclosure provides a circuit comprising: a 4-20 mA transmitter; a transformer having a primary winding and a secondary winding; a first current-sense resistor connected in series with the primary winding and a current regulator, wherein the current-sense resistor is configured to measure a first voltage and provide the measured first voltage to the current regulator, the current regulator being configured to output a current proportional to the measured first voltage; and a second current-sense resistor connected in series with the secondary winding, wherein the current-sense resistor is configured to measure a second voltage such that a current associated with the 4-20 mA transmitter is determined based on the second voltage.

Abstract: The present disclosure provides a circuit comprising: a 4-20 mA transmitter; a transformer having a primary winding and a secondary winding; a first current-sense resistor connected in series with the primary winding and a current regulator, wherein the current-sense resistor is configured to measure a first voltage and provide the measured first voltage to the current regulator, the current regulator being configured to output a current proportional to the measured first voltage; and a second current-sense resistor connected in series with the secondary winding, wherein the current-sense resistor is configured to measure a second voltage such that a current associated with the 4-20 mA transmitter is determined based on the second voltage.

Abstract: The described methods and systems enable a control panel for a safety valve in a safety system of a process control environment to couple to a safety loop that couples a logic solver to a valve positioner for the safety valve. The control panel may drive a loop current on the safety loop to a desired range, thereby causing the valve positioner to respond by initiating a desired function triggered by the loop current entering the desired range. The desired function may be a trip function, a reset function, or a stroke test function.

Abstract: An example visual indicator includes a base defining a light chamber and a first cover removably coupled to the base to cover the light chamber. A light assembly is positioned in the light chamber of the base. The light assembly has a first connector projecting from the base and the first connector is to pass through an access opening formed in an outer surface of a control panel when the visual indicator is coupled to the control panel. The base is to engage the outer surface of the control panel when the visual indicator is coupled to the control panel. The visual indicator is to enable an ingress protection rating of the control panel to be maintained when at least one of the visual indicator is removed from the control panel or the first cover of the visual indicator is replaced with a second cover different than the first cover.

Abstract: Visual indicator apparatus for use with control panels and related methods are disclosed. An example visual indicator disclosed herein includes a base defining a light chamber and a first cover removably coupled to the base to cover the light chamber. A light assembly is positioned in the light chamber of the base. The light assembly has a first connector projecting from the base and the first connector is to pass through an access opening formed in an outer surface of a control panel when the visual indicator is coupled to the control panel. The base is to engage the outer surface of the control panel when the visual indicator is coupled to the control panel. The visual indicator is to enable an ingress protection rating of the control panel to be maintained when at least one of the visual indicator is removed from the control panel or the first cover of the visual indicator is replaced with a second cover different than the first cover.

Abstract: Switch apparatus for enclosures having environmental protection are disclosed. In one example, an apparatus includes a housing having a first cavity and a second cavity, and a mounting plate coupled to the housing. The mounting plate is to cover the first and second cavities. An indicator light is coupled to the mounting plate adjacent the first cavity, and a hand-operated switch coupled to the mounting plate adjacent the second cavity.

Abstract: Switch apparatus for enclosures having environmental protection are disclosed. An example apparatus includes a hand-operated switch actuator spaced apart from a first side of a wall of an enclosure having environmental protection. The apparatus also includes a magnet attached to the switch actuator and a magnetically-responsive switch disposed adjacent a second side of the wall. Movement of the switch actuator is to change a position of the magnet to operate the magnetically-responsive switch.