1. Process Control Loop and Calibration

2. Electrical Safety, 4-20 mA, 24V, No Harm
Normal instrumentation signals are 4-20 mA and voltages 24 V and below.
Older instrumentation systems can be mA
48 V and 96 V supplies
Many instruments require line power, 120 V ac
Many instrumented systems switch 120, 240, even 480 V ac.
Process heating circuits
Pump controls
Never assume low voltage, always take the same precautions you would take working with high power electrical circuits .

3. Process loops Process loop and control signals take many forms.
Analog:
4-20 mA signal, most common
3-15 PSI, old control system technology, still in use
10-50 mA signal, old technology, isolated use
Digital equivalents
Foundation Fieldbus
ProfiBus
HART
ControlNet – DeviceNet
Ethernet IP

4. Control Loop Basics Current Loop
4 to 20 mA analog (2-wire) signal for communication between instruments, controllers, and indicators
Instrumentation
Transmitter
2200 ºC
2200 ºC
SENSOR
zero
span
Controller
PLC, DCS
Indicator
CONTROL ELEMENT

5. Transmitter basics
Primary function: Accurately “transmit” a signal proportionate to the measured PV.
4-20 mA (common),1-5 V (rare) analog outputs
HART, Fieldbus, ProfiBus digital outputs
Analog and smart versions
HART smart versions can be mA, digital output or both
Analog versions are fixed range.
Basic signal conditioner technology
Smart versions can be digitally re-ranged.
Microprocessor controlled
PV: Primary variable, e.g.: temperature, pressure, flow…
HART: Highway Addressable Remote Transducer

6. As Found / As Left Test As found
The verified condition of a device prior to adjustment
If the test results are within the specified values no adjustment is required.
Adjustment if necessary
As left
The verified condition of a device after adjustment
If the results are within the specified values no further adjustment is required.
If fails, readjust, re-run as left until the test passes.
If the device fails as left after several re-tries, it may be defective and need replacement.

7. What is calibration? Calibration does not mean adjustment…
Calibration is:
Comparison of a measured value to a traceable measurement standard.
Adjust to agree with a standard, if necessary.
Reasons to calibrate:
Product quality, quality standards
Regulatory compliance
Personal safety

8. Calibration Documentation
A documented calibration requires:
Tag, model and serial number of the device.
Name of person performing the task.
Calibration device and its’ certification information.
When calibrated and when due for re-calibration
Date and time performed.
Test tolerance.
As found data.
Applied value, measured value, error calculation
As left data if adjustment is performed.

9. Typical Transmitter, Temperature
Converts low level, non-linear thermocouples, RTD signals to linear mA or dc voltage.
Millions in service, require service and calibration
“A temperature controlled current regulator” + –
Sensor Input
Thermocouple
RTD
Thermistor
24 V Loop Supply
ZERO
SPAN
Thermocouple Transmitter
0 to 300 Deg C 7 6

10. Typical Transmitter, Pressure
Converts pressure to linear or square root responding mA or DC voltage
Millions in service, require service and calibration
“Pressure controlled current regulator” + –
Sensor Input
Gage
Absolute
Differential
24 V Loop Supply
Pressure
Input
Current
Output
Percent
of Span
3 PSI
4 mA 0%
6 PSI
8 mA
25%
9 PSI
12 mA
50%
12 PSI
16 mA
75%
15 PSI
20 mA
100%
Pressure Transmitter
3 to 15 PSI 7 6

11. I to P Transmitters
I to P converts a 4-20 mA signal to a 3-15 PSI signal
Often used with control valves
Used as a bridge between 4-20 mA loop and 3-15 PSI pneumatic technology
Typically operate from a 20 PSI or greater pressure supply
“A current controlled pressure regulator”
Pressure Output
4-20 mA Current input
Current
Input
Pressure
Output
Percent
of Span
4 mA
3 PSI 0%
8 mA
6 PSI
25%
12 mA
9 PSI
50%
16 mA
12 PSI
75%
20 mA
15 PSI
100%
Supply
Pressure
~20 PSI

12. Current loop devices Transmitters
Temperature, pressure, flow, analytical
I to P, 4-20 mA input, 3-15 PSI output
Control valves
PLC and DCS analog inputs
Indicators
Controllers
Flow computers
Chart recorders
PLC: Programmable Logic Controller
DCS: Distributed Control System

13. HART Communication “101” What is HART? The HART Foundation
Highway Addressable Remote Transducer
An industry standard developed to define the communications protocol between intelligent field devices and a control system.
The most popular digital communication standard in the field today.
The HART Foundation
An independent not-for-profit organization that supports the application of HART technology worldwide
Fluke is a member of this organization. .

14. Why HART?
Enhances operation of field devices by allowing digital communication
Important benefits:
Allows simultaneous 4-20 mA analog signal and digital over same wiring.
Existing cabling can be used.
Current control strategies remain secure.
Additional information can be transmitted.
Tag numbers, measured values, range and span data, product information and diagnostics.
Reduces operation costs.
Important information is available for installation, calibration and maintenance.
Improved management and utilization of “smart” instrument networks.

15. Simultaneous Analog and Digital
Asynchronous serial communication
Very much like RS-232
HART uses a Frequency Shift
Keying (FSK) signal superimposed
upon the 4-20 mA analog signal.
FSK used is the same as
American Bell 202 standard.
1200 baud
1 start bit, 8 data bits, 1 parity
bit (odd), 1 stop bit, signal
4-20 mA Analog
Average value is zero; no DC signal is
added to low level (4-20 mA) analog.
Low pass (noise) filtering easily removes communication signal.
+0.5 mA
0 mA
-0.5 mA
1200 Hz
“1”
2200 Hz
“0”
넓은 의미의 주파수 변조(FM)의 한 형태로, 디지털 신호를 아날로그 전송로를 통하여 전송할 때 사용하는 변조 방식. 중심 주파수를 삽입한 고주파수와 저주파수 2개의 주파수에 2진수 1과 0이 대응한다. 즉 1과 0의 신호에 각각 f1, f0의 2개 주파수가 할당된다. 고주파수와 저주파수의 2개의 상태를 사용하기 때문에 잡음에 강한 반면 고속 전송에는 부적합하다. 200~1,200bps의 저속 회선용 모뎀에서 사용된다.

16. A Smart System
The HART Signal

17. 744 HART “Communication Tree”

18. 744/HART Terminology PV - Primary measured variable
PVAO - Digital representation of analog output
PV LRV - PV lower range value
PV URV - PV upper range value
SV - Secondary measured variable
TV - Tertiary measured variable
QV - Quaternary measured variable
Trim - Digital adjustment

19. Analog vs. Smart Transmitters
Analog Transmitter
Zero
Span
Analog Electronics
Input Sensor
4-20 mA Output
Smart Transmitter
PV URL
PV LRL
Sensor Trim
Pressure Zero
Loop Test
Output Trim
Input
Sensor
Sensor
Input
Range Computation
Instrument Output
4-20 mA
Output PV
PVAO

20. Smart Transmitter Adjustments
When and what do you adjust?
If only analog signal is used:
Treat just like other analog transmitters; adjust the zero and span as needed.
If operated in the digital mode:
Sensor trim is needed – only the PV is used.
Sensor
Input
Range Computation
Instrument Output
4-20 mA
Output PV
PVAO
Sensor Trim
Pressure Zero
PV URL
PV LRL
Loop Test
Output Trim
Smart Transmitter

21. Do smart transmitters need maintenance ?
Yes!!!
True, smart transmitters are generally more stable and are much higher performance.
They have to be calibrated (or at least verified) with real, traceable standard - this is no different than any other analog measuring device!
At regular intervals
Requires a communicator and a calibrator
<or>
A calibrator with an integrated HART communicator.

22. Commissioning Utilities
In initial commissioning, the transmitter needs to be:
Tagged.
PV units set.
Ranging set.
Damping adjusted.
Transfer function changed .
Pressure only
Sq, root, linear
Use Fluke 744 or HART Communicator

23. Configuring the temperature sensor on a smart temperature transmitter
Smart temperature transmitters can be configured for a variety of sensors.
Thermocouples (many types)
RTD (many types); 2-, 3- or 4-wire

24. Multi-variable Transmitters
Many smart transmitters have multiple temperature and pressure sensor inputs.
Temperature:
Sensor burnout protection (back up sensor)
Temperature differential measurements
Temperature averaging measurements
Pressure:
Static pressure
Differential pressure

25. HART Utilities Smart Transmitter
“Loop test” sets the transmitter output to a specified 4-20 mA signal by issuing a PVAO command.
Tests output stage of transmitter, input of PLC or other device
Input trim, trim the sensor block
Output trim, adjust the output D/A, mA output circuit
Smart Transmitter
Sensor Trim
Pressure Zero
PV URL
PV LRL
Loop Test
Output Trim
Input
Sensor
Sensor
Input
Range Computation
Instrument Output
4-20 mA
Output PV
PVAO

26. HART Summary
HART is the most widely used digital communication protocol in the process industry.
Supported by an industry backed non-profit organization
HART allows traditional 4-20 mA signals to co-exist with more modern digital communication.
Offers an opportunity for Fluke to continue its leadership position in the high-end of the Process Calibration market.
Not the most talked about digital communication protocol but the largest installed base.
5 million instruments installed worldwide in over 10,000 plants.

27. Software for calibration data management
Software solutions complete the documenting requirements for a documenting calibrator.
Many different solutions from fully integrated CMMS to stand alone CMS.
Vary in complexity (and price, $2K to $100K)
CMMS = Computerized Maintenance Management Software
CMS = Calibration Management Software

28. Calibration Management Software Solutions; Docking
Fluke DPC/TRACK
Honeywell DocuMint
Fisher Rosemount AMS
Yokogawa PRM
AST Cornerstone
Beamex QM6
ProCal V
Meridium

29. Example CMS Software: DPC/TRACK
Entry level instrumentation database, simple CMS product

30. What does a CMS package do?
Creates custom procedures.
Allows results to be uploaded and stored in database .
Prints reports that support ISO 9000 documentation.
Searches for particular tags and reports their history.
Keeps track of all tags “touched” by a particular piece of instrumentation.
Tracks due dates for specific tags.

31. Sample DPCTRACK (free)
Sample software included with the 743B/744.
Real Software, limited by:
Includes 10 sample tags, 5 user tags; SampleTag1, SampleTag2...
Only sample tags allowed in database.
Sample tag information & history is editable.
History data on sample tags is maintained.
All DPC calibration data can be uploaded, reports printed, and exported to CSV data files.
Perfect for use as an unloading utility.

32. Instrument View Search Screen
Search for tags by:
Tag Id
S/N
Location
Device type
Other sort masks

33. Tag Instrument Data

34. Transmitter Data

35. Calibrator Setup Data

36. Develop Test Procedures

37. Custom Test Procedures
Task prompts
Pre- or post-test prompts
Use for procedure steps, location of tags, hook up instructions, lockout/tagout.
User defined pick lists
Imbed in procedures loaded into DPCs
Document observations and related maintenance tasks.
Documented with as found/as left results.

38. Schedule Workload

39. Upload and download information to DPCs

40. Review Test Results

41. Graph, Analyze Test Results

42. Evaluating Long Term Performance
Graphical trending analysis