How to get value out of HART Ensure HART is always connected Topics - - PowerPoint PPT Presentation

How to get value out of HART

Ensure HART is always connected

Topics Covered

 Background  Training  Design  Procurement  Integration  Configuration  Factory Acceptance Test (FAT)  Installation  Commissioning  Change Work Practices  Network Maintenance  System Management

Design Procurement Integration Configuration FAT Installation Commissioning Operation

Background

Put HART to good use

Consumption Gap

 Plants are built with intention to use HART  Plants struggle to utilize HART  HART only used for commissioning with the handheld field communicator

• The control system uses only 4-20 mA signal

 Only some plants use HART always connected

• Only some devices use HART always connected

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Digital HART is Not the Same as Analog 4-20 mA

 HART does not get designed and procured correctly  Not installed and commissioned correctly  Not integrated and setup properly  Not maintained properly  People don’t get trained  Plant ends up using only handhelds or laptop with HART modem, missing out on the smart always connected capabilities

If you will only use a handheld you need not worry about most of this…

HART Training

Competency is a critical success factor

HART Training Required

 There are many misconceptions around HART

• The reason why in the end HART is underutilized

 Use consultants, EPC contractors, and subcontractors trained in HART  Train plant personnel on HART to ensure continuity

• If not HART will fall into disuse

 Get trained on HART

250 ohm Filter Line Conditioner Capacitance Noise 600 ohm Master conflict HART7 DD file Report by Exception

HART Design

Design for digital, not just analog

System HART Pass-Through

New systems  Make sure analog input and analog output cards support HART communication  Compliant with HCF_SPEC- 054  HART pass-through across the higher level network Existing control systems not supporting HART  Install wireless adapters on selected instruments  Plant-wide wireless gateway infrastructure

HART Cable Selection

 Individually shielded twisted pair cable

• Single pair or multi-pair

 Minimum conductor size:

• 0.2 mm2 (#24 AWG) for cable runs less than 1.5km
• 0.5 mm2 (#20 AWG) for longer distances

 Compliant to the HCF_SPEC-054 specification  Polyethylene (PE) insulation is preferred

• Lower capacitance than PVC insulation
• More stable, will not increase as much over time

 Low capacitance good-quality cable

• Mutual capacitance of 60 nF/km is available

 Additional cable requirements may apply depending on the hazardous area classification and local regulations etc.

Similar to FF and

• ther digital

communication

an

Loop Resistance

 HART loop resistance max 600 ohm

• Distance limitation on the wires

 250 ohm resistor not required for valve positioner  Calculate the voltage drop to ensure I/O card voltage is sufficient for all the loads in the loop:

• Transmitter, positioner, indicator, signal conditioner, wireless

adapter, filter, line conditioner, wire resistance

 Each type of device and option is different  Replacement device may be different  Loop current may be as high as 23 mA

200 400 600 12 14 16 18 VDC

• hm

4-20 mA Operating Area 4-20 mA/HART Operating Area

Loop Resistance Example

 Max loop current is 23 mA  Device requires a minimum of 12 VDC at terminals  Voltage source from the AI card 15 VDC

• Internal 250 ohm shunt resistor

 Maximum permitted loop resistance for the cable is (15- 12)/0.023 = 130 ohm

Loop Capacitance

 Maximum device capacitance is 5 nF  Cable capacitance limits length  Determine max allowable cable length from the 65 microsecond chart  Use low capacitance cable (PE insulation) with large conductor cross section

• A full 1.5 km is possible
• PE insulation cable with mutual capacitance
• f 60 nF/km is available from many vendors

 Additional cable requirements may apply depending on the hazardous area classification and local regulations etc.

HART Capacitance 65 us Chart

Loop Capacitance Example

 Single device, 5 nF device capacitance, 250 ohm shunt resistor  Cable Capacitance: 180 nF/km  Conductor Resistance: 49 ohm/km (22 AWG)

1 km

HART Safety Barriers

 Intrinsic safety barriers have to be HART compatible  Compliant to the HCF_SPEC-054 specification  All intrinsic safety rules apply

Cabling Route Planning (Cable Trays)

 4-20 mA/HART separate from power cables  4-20 mA/HART together with other signal wiring including fieldbus and other data communication  Signal wiring cross power cables at a right angle

Same as FF and

• ther digital

communication >30 cm

Shield Connection

 Shield must be maintained all the way from the field device to the control system I/O card  Shield shall not be connected to the device housing (HCF_SPEC-054 recommendation)

Same as FF and

• ther digital

communication

Do not connect shield +

Enclosure Grounding

 The device housing shall be connected to ground through a large cross-section conductor

Same as FF and

• ther digital

communication

Shield Grounding

 The shield shall be grounded at the control system I/O card (HCF_SPEC-054 recommendation)

Same as FF and

• ther digital

communication

Junction Box

Control System Panel

Shield not connected at device

DCS AI card R Transmitter Filter HART Communicator + R

HART Input Filters

 If system has no low-pass filter in the AI card  Installed near control system AI card  Safe side of safety barrier  May not be suitable for surge controllers  Compliant to the HCF_SPEC-054 specification

HART Output Filters

 If system has no filter in AO card  Installed near control system AO card  Safe side of safety barrier  Need sufficient AO card compliance voltage  Some 4-20 mA simulators (loop calibrators) also require a HART output filter  Compliant to the HCF_SPEC-054 specification

DCS AO card Valve Positioner Filter HART Communicator

Logic Solver DO card Partial Stroke Test Device HART Communicator Line Conditioner S Solenoid Valve +

HART Line Conditioners

 Used with Partial Stroke Test (PST) device on shutdown valve  Most logic solvers have no filter in the DO card  Compliant to the HCF_SPEC-054 specification

Similar to FF

HART Compliant Devices

 Devices which have not been registered may not be fully compliant  Configuration, diagnostics, auxiliary variables may not work properly  Nuisance alarms  Specify “Device shall be HART Registered”

Same as FF and

• ther digital

communication

HART Loop Power Supply

 Free from ripple and noise

• Less than 2.2 mV RMS

 Old, faulty, or overloaded power supply may be a source

• f noise

 Compliant to the HCF_SPEC-054 specification

HART Master Conflict

 Only two HART masters  Masters must be different class;

• One primary; control system, MUX, wireless adapter,

smart signal conditioner

• One secondary; handheld, laptop with HART modem,

wireless adapter, smart signal conditioner  If two or more masters of the same class are connected the communication will fail

• Smart signal conditioner will set the analog output < 4

mA or > 20 mA tripping loop

HART Burst Communication

 Do not use burst in devices connected to a control system

• r multiplexer
• Mostly used for stand-alone smart signal conditioners

 Cause diagnostics and auxiliary variable monitoring etc. to slow down

• Nuisance alarms in the IDM software

Unpolled Address

 Use a HART version 7 (HART7) host to ensure all devices are detected  Version 5 of HART (HART5) only supports address up to 15  Older hosts do not support polling of addresses up to 63

• Will not detect newer devices such as wireless

adapters which use default addresses above 15

HART Command 48 (Diagnostics)

 Used for the IDM software alarm management function to filter the instrument diagnostic alarms from the devices

• Optional in HART5 devices
• Mandatory in HART7 devices

 Specify devices shall support command 48

DD Files

 DD files are not required to get a 4-20 mA signal  DD files are required for configuration and diagnostics  Without a DD file it is not possible to properly configure a device to get a correct measurement  Warning: Not all devices come with a DD file

• Configured form a local display or by proprietary

software

• Setting up instrument diagnostic alarm management

filters becomes very challenging  Specify device shall come with DD file

Not all devices come with DD files

Same as FF and

• ther digital

communication

HART7

 HART5 systems cannot support HART7 devices

• Only specify HART7 devices if the system is HART7

compatible  Some devices can be configured to operate as HART5 or HART7

• Essentially two different devices so have two DD files

HART5 system do not support HART7 devices

HART Polling

 Set the polling time as short (fast) as possible  If the polling time is set longer than a minute;

• Intermittent problems may be missed
• Too short time left for operators to respond

 Use polling for diagnostics of 4-20 mA devices

• Triggered burst mode and event notification (“report by

exception”) functions are intended for WirelessHART  Burst communication may interfere with diagnostics polling

HART Procurement

Buy only tested and registered products

HART Procurement

 A non-compliant component could jeopardize the ability to utilize HART capabilities

• The analog 4-20 mA signal will work but the smart

features cannot be accessed and the benefits not reaped  Verify products in bids are tested and registered

HART Integration

Load your DD

Load DD Files on Control System

 Needed to configure diagnostics filtering to display as human readable text  Some control system may also need an internal system specific file for each device type

Load DD Files on IDM Software

 Without DD file

• The device cannot be made to work correctly
• The 4-20 mA signal may not be correct

 Need DD files to commission device

• Configure sensor type and many other settings
• Perform sensor trim and other functions

 Some IDM software may also need an internal system specific file

Load DD Files on Portable Tools

 Without DD file

• The device cannot be made to work correctly
• The 4-20 mA signal may not be correct

 Need DD files to commission device

• Configure sensor type and many other settings
• Perform sensor trim and other functions

DD File for Correct HART Version

 The DD file for HART5 and HART7 version of device is different

• Buy as HART5 or HART7
• Configure as HART5 or HART7

 If the device is configured to operate as HART7 but the HART5 DD has been loaded, the system cannot access the device features

HART Configuration

Engineer to avoid alarm flooding

Avoid Alarm Flooding: Instrument Diagnostic Alarm Management

 If the instrument diagnostic alarm management system is not configured there will be a flood of nuisance alarms

• System will not be used

 ISA108 guidance to being developed  Interim guide:

• http://www.eddl.org/DeviceManagement/Pages/DeviceDiagnostic

s.aspx

 Engineer and setup IDM software before start-up  Specify a control system which is able to categorize instrument diagnostic alarms for command 48  Specify a control system which uses the DD file to display the possible instrument diagnostic alarms from the device as plain text

Instrument Diagnostics Alarm Rationalization

 Categorize severity of diagnostics:

• NAMUR NE107

 Identify criticality to the process for each device tag  Configure system and devices

Same as FF and PROFI

• the
• System shall

display diagnostics items as plain text

Instrument Diagnostic Alarm Routing

Operator Instrument Tech

• Failure
• Function Check
• Failure
• Maintenance Required
• Out of Specification

Devices Nuisance Alarms Same as FF and PROFI

Valve Tight-Shutoff

 If the valve tight-shutoff output current in the control system is configured to 0 mA, HART communication stops when valve is closed

• No power to smart valve positioner
• No power to wireless adapter
• Nuisance communication alarms
• No diagnostics

 The valve tight-shutoff current setting in the control system shall be somewhere in the range 3.6-3.8 mA

• Ensures the positioner still performs diagnostics and

devices plus accessories are able to communicate

HART Factory Acceptance Test (FAT)

Test to make sure instrument diagnostics alarm management will work as intended

Interoperability / Integration Test at FAT

 Connect one of each type of device  Open each type of device in the IDM software

• Verifies the DD file has been loaded for each type and

version of the device

• Verifies the device displays correctly

 Download a device configuration

• Verify the download is error free

Same as FF and

• ther digital

communication

Instrument Diagnostic Alarm Routing Test at FAT

 Simulate instrument diagnostic alarms of different severity (Advisory, Maintenance, and Failure ) for each device type

• Verify they are routed to the right person such as
• perators or instrument technicians

HART Installation

Wiring

Poor Installation Jeopardize the Ability to Utilize HART Capabilities

 The HART signal is small, only 1 mA  Poor installation picks up noise  Communication stops updating in the system:

• Diagnostics
• PV, SV, TV, and QV

 Nuisance communication alarms  Smart signal conditioner output < 4 or > 20 mA which may cause a nuisance trip

Same as FF and

• ther digital

communication

Don’t Ground Shield at Device

 Do not connect the shield or drain wire to ground in the device housing  Ground the shield only in a single point, at the power supply  Only the signal wires are connected at the device  This is the recommendation in the HCF_SPEC-054 specification

• Some plants have other practice

Same as FF and

• ther digital

communication

+

Insulate Shield at Device

 Do not leave the shield or drain wire “flying” as it may come in contact with the device housing  Cut the shield inside the device housing  Isolate the drain wire and shield using shrink tube or tape to make sure it does not come in contact with grounded metal parts  For armored cable, make sure shield drain wire is not touching the cable armor

Same as FF and

• ther digital

communication

+

Maintain Shield Through Junction Boxes

 The shield shall be continuous from system panel, through junction box, up to the device

• But not connected to the device

 Do not ground the shield in the junction box  Do not leave ‘flying’ shield or drain wire as it may touch

• ther wires or grounded metal parts

 If two cables are joined, make sure the junction (splice) also joins the shields of the two cables

Same as FF and

• ther digital

communication

Junction Box

Control System Panel

Shield not connected at device

Route Signal Cables In Separate Tray From Power Cables

 Do not lay communications signal cable in the same tray as power cable  Route signal cable and power cable in separate trays  If signal cable and power cable is laid in the same tray, maintain maximum possible separation, keeping power cable and signal cables on separate sides of grounded metal dividing wall

Same as FF and

• ther digital

communication >30 cm

Min

Observe Cable Minimum Bend Radius

 Loop/bend cable too tight will damage the shield

• Reducing noise immunity

 Cable minimum bend radius

• Cable type dependent
• For armored cable it can be space taking

 Do not turn corners too tight in cable trays

• Use proper cable tray bend, cross, and tee pieces to allow cable

to round corners with wide radius

 “Pig tails” must have a sufficiently large radius to not damage the internal shield  Cable trunking / wire troughs / trays are usually too narrow to permit looping of the cable

Same as FF and

• ther digital

communication

Ground Device Housing

 Without a ground connection the device EMI/RFI suppression will not work  Make sure the device housing is safety grounded to the plant structural steel with a low impedance connection to ensure personnel safety and EMI/RFI suppression  It is particularly important for those devices where surge protection is used

Same as FF and

• ther digital

communication

Ground Junction Boxes

 Make sure the junction box is safety grounded with a low impedance connection  When using plastic junction boxes and metal cable glands, these glands must be connected to the safety ground bar inside the junction box, typically using a metal plate inside junction box

Same as FF and

• ther digital

communication

Cable lug Spring washer Tooth washer

Don’t Coil Signal Cables And Power Cables Together

 Do not coil signal cables and power cables together inside the device terminal compartment

• For example, in separately powered devices such as

Coriolis and magnetic flow meters, etc.  Cables shall be:

• Short
• Jacket on
• Shielded
• Separated

Same as FF and

• ther digital

communication

Signal AC Power

AC Power

Don’t Damage Shield And Conductor Insulation

Cutting Cable Jacket  Do not damage shield and conductor insulation  Do not use a knife

• It might damage the shield

and conductor insulation  Use a cable jacket/sheath stripper Cutting Cable Armor  Do not use a hacksaw

• It might damage the inner

jacket, shield, and conductor insulation  For tube armor use a pipe/tubing cutter  For SWA use a wire cutter to cut strand by strand

Same as FF and

• ther digital

communication

Don’t Strip-Off More Than Necessary

 Maintain shield and jacket as far as possible, close to the connection terminals  Do not remove shield or jacket for cable running in cabinet or junction box

• Bare shields (and drain wire) of different cables will

touch and may cause ground loops  Do not untwist the twisted pair

Same as FF and

• ther digital

communication

Ground Overall Shield For Multi-pair Cable

 The overall shield shall be grounded in the power supply- end  Do not leave overall shield floating  Make sure overall shield does not touch any of the individual pair shields

Same as FF and

• ther digital

communication

Overall Shield Control System Panel

Ground The Cable Armor

 Do not leave the cable armor floating  The metal cable gland must make contact with the amour of the cable at the device and in the junction box  If plastic cable glands are used at the junction box, or the junction box is plastic, the cable armor shall be grounded to safety ground bar  Ground the armor in multiple points:

• Before cable enters marshalling cabinet
• In cable tray
• And in the field junction box

Same as FF and

• ther digital

communication

Armor

Other Good Installation Practices

 Do not pull cable with too much force  Make sure cable glands are tight  Seal unused conduit entries  Use correct size ferrule/fork and tool  Do not cram wires in device terminal compartment  Do not over/under-tighten terminal screws  Make sure covers are tight  Do not tighten cable-tie too much  Label wires  Observe polarity

Same as for any cables

HART Commissioning

Digital loop check

HART Communication Check at Loop Check (Loop Test)

 Also verify the HART communication

• Loop calibrator with HART communication capability
• Handheld field communicator

 Communicate with the device to ensure communication is error free

• Monitor the 4 dynamic variables (PV, SV, TV, and QV)

for some time  Confirms the design and installation is done correctly, so digital communication will be reliable

Similar to FF and

• ther digital

communication

In addition to traditional 5- point loop check

Digital Integration Verification at Loop Check

 Open up each device in the IDM software  Confirms:

• Communication is enabled
• Communication is working from the system end
• The DD file matches the device type and version

 Open the diagnostics page to see if any problem

• Incorrectly wired temperature sensor
• Valve supply air
• Flow meter auxiliary power

Same as FF and

• ther digital

communication Ranges, units…

Change Work Practices for HART

Getting into the habit of using the IDM software as part of the daily routine

Instrument Technician Culture Change

 Review instrument diagnostic alarms

• Instrument technicians must review the instrument

diagnostic alarm summary and log every day

• Spend time on devices which need attention

 Check the software first

• When operations say a device is not working,

instrument technicians must check the software first, before going to the field to take a look

• Avoid unnecessary field visits

 Rewriting Standard Operating Procedures (SOPs)

• Rewrite work procedures to include IDM software
• Inspection, replacement, calibration and other tasks

HART Network Maintenance

Maintain installation in good condition to ensure the HART communication continues to work error free

Safety Instrumented Systems (SIS) Warning

 If device diagnostics is used to claim safety credit, the digital HART communication must maintained functional  Any communication issues must be resolved immediately so the always connected diagnostics monitoring remains functional  If the device is replaced;

• The new device must have the same or better

diagnostics

• Must be digitally integrated

.

Troubleshoot – Don’t Disable

 If nuisance communication alarms appear personnel will disable HART

• Only analog 4-20 mA remains

 Troubleshooting should instead be done to bring HART communication back alive

HART Issues Develop Over Time

 Somebody ground cable shield  Inadvertent contact between shield and ground  High loop resistance due to corroded terminals  Added series devices like a wireless adapter  Device replaced with non-HART device  New source of noise  Moisture in device compartment or field junction box  Loose connections due to vibration  High capacitance in aging cable or stray capacitance  Device replaced with wrong HART protocol version  Replacement device not configured correctly  Additional master connected causing master conflict  Shield damaged  Shield continuity compromised  Housing ground disconnected  Field junction box ground corroded

Similar to FF and

• ther digital

communication

Monitor HART Network Health

 Periodically check HART communication Packet Error Rate (PER) to detect deteriorating communication before alarms appear

• Built-in control system communication diagnostics
• External HART analyzer software with HART modem

Same as FF and

• ther digital

communication

Maintain Installation Integrity

 Technicians must be familiar with the additional requirements of digital HART or mistakes will happen:

• Connecting shield to the ground screw on the device
• Contact between shield and device housing
• Device housing not grounded

 Tighten covers and close doors to make sure and terminals do not corrode  Make sure connections have not come loose due to vibration, including ground connections  Look for shield damage and shield continuity  Check for noise

Management of Change

 Replacement device must be:

• HART-enabled
• Correct HART protocol version
• Tested and registered
• Supports command 48
• Comes with a DD file
• Configured for communication and diagnostics

 If a HART master is added make sure there is no master class conflict  If device is added in the loop make sure the voltage is sufficient  Make sure sources of noise are not introduced  Make sure new cable is laid in the correct trays

HART Troubleshooting

 Troubleshooting digital HART is different from troubleshooting analog 4-20 mA  It is not possible to troubleshoot HART with a multimeter  Troubleshooting guide for HART and other field communication:

• http://www.eddl.org/SiteCollectionDocuments/TechPap

ers/ag_Field%20Communication%20Troubleshooting. pdf

HART System Management

Keep system up to date with new device types and versions

Keep System Up to Date

 Without the DD files the devices cannot be configured or diagnosed  If the IDM software is not loaded with DD for new devices and revisions it will fall into disuse

• Only analog 4-20 mA to control system remains

 Load the DD files for new device types and versions on the control system and IDM software

Same as FF and

• ther digital

communication

DD File Management

 DD files are easy to download from the Internet  It is a good idea to load any DD files available

• This way the system is ready for all kinds of devices

 Some systems have DD wizard that automatically distributes the DD to all workstations  Consider using DD update services which loads DD files

• nto the system automatically as they become available

DTM Driver Software Management

 Ensure DTM for the device is available for the particular Windows version used  Only install the DTMs you really need

• Avoid conflicts
• Reduce burden on the computers

 Ensure instrument technicians can install DTM software for new device types and versions  Instrument technicians may need to be given ‘administrator’ level password  Install DTMs on all IDM workstations  Use only certified DTMs  Use only DTMs from the original device manufacturer

• Not third-party DTMs

 DTM may require license to unlock device capabilities  Make sure all DTMs are available for the new Windows version before upgrading Windows

Make Sure DD Files are Available

 A replacement device must be registered and must come with DD files  Not all HART devices have DD files

• Make sure a device comes with DD files before

purchasing it

Conclusion

“Get Connected”

 Many plants only use HART with handheld  Engineer correctly

• Design according to the rules
• Procure tested and registered
• Install and commission according to the rules
• Integrate and setup properly
• Maintain properly
• Train people

 Get a field communications expert involved