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 o The control system uses only 4-20 mA signal  Only some plants use HART always connected o Only some devices use HART always connected Courtesy - B4B: How Technology and Big Data Are Reinventing the Customer-Supplier Relationship

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 o 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 o If not HART will fall into disuse  Get trained on HART Report by Exception DD file Master conflict 600 ohm 250 ohm Filter HART7 Noise Line Conditioner Capacitance

HART Design Design for digital, not just analog

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

Similar to FF and other digital HART Cable Selection communication  Individually shielded twisted pair cable o Single pair or multi-pair  Minimum conductor size: o 0.2 mm2 (#24 AWG) for cable runs less than 1.5km o 0.5 mm2 (#20 AWG) for longer distances  Compliant to the HCF_SPEC-054 specification  Polyethylene (PE) insulation is preferred o Lower capacitance than PVC insulation o More stable, will not increase as much over time  Low capacitance good-quality cable an o Mutual capacitance of 60 nF/km is available  Additional cable requirements may apply depending on the hazardous area classification and local regulations etc.

Loop Resistance  HART loop resistance max 600 ohm o 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: o 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 ohm  Loop current may be as high as 23 mA 600 400 4-20 mA/HART Operating Area 200 4-20 mA Operating Area 0 12 14 16 18 VDC

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 o 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 o A full 1.5 km is possible o PE insulation cable with mutual capacitance of 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

Same as FF and other digital Cabling Route Planning (Cable Trays) communication  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 >30 cm

Same as FF and other digital Shield Connection communication  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) Do not connect shield + -

Same as FF and other digital Enclosure Grounding communication  The device housing shall be connected to ground through a large cross-section conductor

Same as FF and other digital Shield Grounding communication  The shield shall be grounded at the control system I/O card (HCF_SPEC-054 recommendation) Control System Panel Shield not connected at device Junction Box

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 DCS HART Communicator AI card + R Filter Transmitter R

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 HART Communicator AO card Filter Valve Positioner

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

Same as FF and other digital HART Compliant Devices communication  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 ”

HART Loop Power Supply  Free from ripple and noise o Less than 2.2 mV RMS  Old, faulty, or overloaded power supply may be a source of noise  Compliant to the HCF_SPEC-054 specification

HART Master Conflict  Only two HART masters  Masters must be different class; o One primary; control system, MUX, wireless adapter, smart signal conditioner o 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 o 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 or multiplexer o Mostly used for stand-alone smart signal conditioners  Cause diagnostics and auxiliary variable monitoring etc. to slow down o 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 o 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 o Optional in HART5 devices o Mandatory in HART7 devices  Specify devices shall support command 48

Same as FF and other digital DD Files communication  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 o Configured form a local display or by proprietary software o Setting up instrument diagnostic alarm management filters becomes very challenging  Specify device shall come with DD file Not all devices come with DD files

HART7  HART5 systems cannot support HART7 devices o Only specify HART7 devices if the system is HART7 compatible  Some devices can be configured to operate as HART5 or HART7 o Essentially two different devices so have two DD files HART5 system do not support HART7 devices