RF ADAPTER FOR FIELD DEVICE WITH LOW VOLTAGE INTRINSIC SAFETY CLAMPING

• US 20090253388A1
• Filed: 06/17/2009
• Published: 10/08/2009
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Orth, Kelly M., Westfield, Brian L., Kielb, John A.
• Granted Patent: US 8,787,848 B2
• Time in Patent Office: Days
• US Class Current: 455/117
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G05B 19/4185 characterised by the network communication
• CPC Class Codes: G05B 2219/31121 Fielddevice, field controller, interface connected to fieldbus
• CPC Class Codes: G05B 2219/33192 Radio link, wireless
• CPC Class Codes: G05B 2219/34313 Power supply for communication delivered by, derived from 4-20-mA current loop
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]
• CPC Class Codes: Y02P 90/80 Management or planning

Abstract

An adapter for coupling to a process control transmitter of the type used to monitor a process variable in an industrial process includes a first connection configured to couple to a first side of a two wire process control loop, a second connection configured to couple to a second side of the two wire process control loop and in series with a first connection to a process control transmitter, and a third connection configured to couple to a second connection of the process control transmitter. Wireless communication circuitry is coupled to at least the third connection and is configured to provide wireless communication for the process control transmitter. Intrinsic safety circuitry coupled to at least one of the first, second and third connections is configured to limit transfer of electrical energy to a value which is less than an intrinsic safety value.

Claims

1. An adapter for coupling to a process control transmitter of the type used to monitor a process variable in an industrial process, the adapter comprising:

a first connection configured to couple to a first side of a two wire process control loop;

a second connection configured to couple to a second side of the two wire process control loop and in series with a first connection to the process control transmitter;

a third connection configured to couple to a second connection of the process control transmitter;

wireless communication circuitry configured to provide wireless communication for the process control transmitter; and

intrinsic safety circuitry coupled to at least one of the first, second and third connections configured to limit energy transfer to a value which is less than an intrinsic safety value.

2. The apparatus of claim 1 wherein the intrinsic safety circuitry comprises a diode.

3. The apparatus of claim 2 wherein the diode comprises a zener diode.

4. The apparatus of claim 2 wherein the diode is connected between the first and second connections.

5. The apparatus of claim 2 wherein the diode is connected between the second and third connections.

6. The apparatus of claim 2 wherein the diode is connected between the first and third connections.

7. The apparatus of claim 1 wherein the intrinsic safety circuitry is coupled between the first, second and third connections.

8. The apparatus of claim 1 including a capacitor configured to store energy for use in operating the wireless communication circuitry.

9. The apparatus of claim 8 wherein the capacitor comprises a super capacitor.

10. The apparatus of claim 1 wherein the intrinsic safety circuitry comprises active circuitry.

11. The apparatus of claim 10 wherein the active circuitry is configured to provide triple redundancy of components.

12. The apparatus of claim 10 wherein the active circuitry comprises an active shunt.

13. The apparatus of claim 1 including a fuse coupled in series with at least one of the first, second and third connections.

14. The apparatus of claim 8 wherein the intrinsic safety circuitry is coupled in series between the capacitor and the at least one of the first, second and third connections.

15. The apparatus of claim 14 wherein the intrinsic safety circuitry comprises a diode.

16. The apparatus of claim 14 wherein the intrinsic safety circuitry comprises a resistance.

17. The apparatus of claim 1 wherein the intrinsic circuitry is configured to limit storage of electrical energy stored in the adapter to a value which is less than the intrinsic safety value.

18. The apparatus of claim 1 wherein the wireless communication circuitry is powered with electrical power received from the two wire process control loop.

19. The apparatus of claim 1 including communication circuitry configured to communicate with the process control transmitter.

25. The method of claim 1 wherein the step of limiting user active circuitry.

20. A method of coupling a wireless adapter to a process control transmitter of the type used to monitor a process variable in an industrial process, the method comprising:

coupling a first connection to a first side of a two wire process control loop;

coupling a second connection to a second side of a two wire process control loop and in series with a first connection to the process control transmitter;

coupling a third connection to a second connection of the process control transmitter;

powering wireless communication circuitry with power received from the two wire process control loop; and

limiting energy transfer to a value which is less than an intrinsic safety value.

21. The method of claim 20 wherein limiting energy transfer comprising limiting energy going into circuitry of the adapter.

22. The method of claim 20 wherein limiting energy transfer comprising limiting energy coming out of circuitry in the adapter.

23. The method of claim 20 including storing energy in a capacitor.

24. The method of claim 23 wherein the capacitor comprises a super capacitor.

26. The method of claim 21 including limiting storage of electrical energy in the adapter to a value which is less than the value of the intrinsic safety value.

27. The method of claim 20 including communicating with the process control transmitter using the third connection.