Process control instruments having local intrinsic safety barriers and methods of manufacturing the same

Patent metadata

Field	Value
Publication number	US-12355235-B2
Application number	US-202318176322-A
Country	US
Kind code	B2
Filing date	Feb 28, 2023
Priority date	Feb 28, 2023
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

Process control instruments having local intrinsic safety barriers and methods of manufacturing the same are disclosed. An example field instrument for a process control assembly includes a non-protection compartment, intrinsically safe circuitry positioned in the non-protection compartment, a protection compartment, non-intrinsically safe circuitry positioned in the protection compartment, and local barrier circuitry positioned in the protection compartment to operatively couple the non-intrinsically safe circuitry to the intrinsically safe circuitry, the local barrier circuitry to prevent the intrinsically safe circuitry from receiving an electrical energy that is greater than an electrical energy threshold from the non-intrinsically safe circuitry.

First claim

What is claimed is:

1. A field instrument for a process control assembly comprising:
a non-protection compartment;
intrinsically safe circuitry positioned in the non-protection compartment;
a protection compartment;
non-intrinsically safe circuitry positioned in the protection compartment; and
local barrier circuitry positioned in the protection compartment to operatively couple the non-intrinsically safe circuitry to the intrinsically safe circuitry, the local barrier circuitry including a first portion to prevent the intrinsically safe circuitry from receiving a first signal having a first electrical energy that is greater than an electrical energy threshold from the non-intrinsically safe circuitry, the local barrier circuitry including a second portion to prevent the intrinsically safe circuitry from receiving a second signal having a second electrical energy that is greater than a second electrical energy threshold from the non-intrinsically safe circuitry, the first portion of the local barrier circuitry distinct from the second portion.

2. The field instrument of claim 1 , wherein the protection compartment is mechanically coupled to the process control assembly.

3. The field instrument of claim 1 , wherein the local barrier circuitry includes voltage reduction circuitry, control signal barrier circuitry, and communication signal barrier circuitry, the voltage reduction circuitry to relay the first signal to the control signal barrier circuitry, the control signal barrier circuitry to transmit the first signal to the intrinsically safe circuitry, the communication signal barrier circuitry to receive the second signal from the non-intrinsically safe circuitry upstream of the voltage reduction circuitry, the communication signal barrier circuitry to transmit the second signal to the intrinsically safe circuitry.

4. The field instrument of claim 3 , wherein the voltage reduction circuitry includes a transistor, a resistor, and an operational amplifier, wherein the operational amplifier causes the second signal to pass through the transistor in response to a voltage of the second signal satisfying a voltage threshold, and wherein the operational amplifier causes the second signal to pass through the resistor in response to the voltage not satisfying the voltage threshold.

5. The field instrument of claim 3 , wherein the local barrier circuitry includes a fuse to couple the voltage reduction circuitry to the control signal barrier circuitry.

6. The field instrument of claim 1 , wherein the non-intrinsically safe circuitry includes electromagnetic interference filter circuitry to transmit the first signal and the second signal to the local barrier circuitry.

7. The field instrument of claim 1 , wherein the first signal is to control an actuator of the process control assembly, and wherein the second signal is indicative of a status or configuration of the process control assembly.

8. The field instrument of claim 1 , wherein the intrinsically safe circuitry includes current-to-pressure transducer circuitry to cause a positional adjustment of a valve of the process control assembly based on the first signal.

9. The field instrument of claim 1 , wherein the intrinsically safe circuitry includes user interface circuitry, the non-protection compartment to enable an operator to interact with the user interface circuitry via touch.

10. The field instrument of claim 9 , wherein the non-protection compartment is exposed to a flammable media.

11. A field instrument for a process control assembly comprising:
a non-protection compartment;
intrinsically safe circuitry positioned in the non-protection compartment;
a protection compartment;
non-intrinsically safe circuitry positioned in the protection compartment; and
local barrier circuitry positioned in the protection compartment to operatively couple the non-intrinsically safe circuitry to the intrinsically safe circuitry, the local barrier circuitry to prevent the intrinsically safe circuitry from receiving an electrical energy that is greater than an electrical energy threshold from the non-intrinsically safe circuitry, wherein the local barrier circuitry includes a first electrical coupling, a second electrical coupling, a fuse, a Zener diode, and a semiconductor controlled rectifier, wherein the fuse is to couple the first electrical coupling to the non-intrinsically safe circuitry, wherein the Zener diode includes a first terminal and a second terminal, wherein the semiconductor controlled rectifier includes a first terminal coupled to the first electrical coupling, a second terminal coupled to the second electrical coupling, and a gate terminal coupled to the second terminal of the Zener diode, wherein the Zener diode is configured to trip the semiconductor controlled rectifier in response to encountering a voltage that satisfies a first voltage threshold, wherein the semiconductor controlled rectifier is configured to trip the fuse in response to being tripped.

12. The field instrument of claim 11 , wherein the Zener diode is a first Zener diode, wherein the local barrier circuitry further includes a second Zener diode, wherein the second Zener diode includes a first terminal and a second terminal, wherein the first terminal of the second Zener diode is coupled to the first electrical coupling downstream of the first terminal of the first Zener diode, wherein the second terminal of the second Zener diode is coupled to the second electrical coupling, wherein the first Zener diode has a first Zener voltage and the second Zener diode has a second Zener voltage, the second Zener voltage greater than the first Zener voltage to prevent the second Zener diode from delivering an electrical current to the second electrical coupling when the first Zener diode trips the semiconductor controlled rectifier.

13. An apparatus comprising:
a process control assembly;
a power supply; and
a field instrument positioned local mechanically coupled directly to the process control assembly via a first coupling, the field instrument including:
a non-protection compartment;
intrinsically safe circuitry positioned in the non-protection compartment;
a protection compartment;
non-intrinsically safe circuitry positioned in the protection compartment, the non-intrinsically safe circuitry electrically coupled to the power supply via a second coupling distinct from the first coupling; and
local barrier circuitry positioned in the protection compartment to operatively couple the non-intrinsically safe circuitry to the intrinsically safe circuitry, the local barrier circuitry to prevent the intrinsically safe circuitry from receiving an electrical energy that is greater than an electrical energy threshold from the non-intrinsically safe circuitry.

14. The apparatus of claim 13 , wherein the local barrier circuitry includes voltage reduction circuitry, control signal barrier circuitry, and communication signal barrier circuitry, the voltage reduction circuitry to relay a first signal to the control signal barrier circuitry, the control signal barrier circuitry to transmit the first signal to the intrinsically safe circuitry, the communication signal barrier circuitry to receive a second signal from the non-intrinsically safe circuitry upstream of the voltage reduction circuitry, the communication signal barrier circuitry to transmit the second signal to the intrinsically safe circuitry.

15. The apparatus of claim 14 , wherein the voltage reduction circuitry includes a transistor, a resistor, and an operational amplifier, wherein the operational amplifier causes the second signal to pass through th

Assignees

• Fisher Controls Int Llc

Inventors

• Arnold Chris
• Bulleit Gregory R
• Nicholas Davin
• Wittkop Adam
• Brama Marwan Saputera
• Seberger Stephen G

Classifications

• H02H9/02

  responsive to excess current {(current limitation for voltage regulators G05F1/573; disconnection after limiting H02H3/025)} · CPC title

• H02H9/046

  responsive to excess voltage appearing at terminals of integrated circuits · CPC title

• F16K37/0066

  Hydraulic or pneumatic means (F16K37/0075 takes precedence) · CPC title

• A62C3/16

  in electrical installations, e.g. cableways · CPC title

• H02H5/041

  additionally responsive to excess current (H02H5/048 takes precedence) · CPC title