Delta 2HT User Manual

Smart 2HT transmitter

Issue Feb 10

How can we help you?

Technical Datasheets and IOM Instructions for all
Delta Controls' pressure and temperature
measurement products are available from our
website at www.delta-controls.com.

For Service and Repair enquiries, please contact the
Sales Engineering Teams on [phone]
or email [e-mail].

Delta Controls Limited

Island Farm Avenue, West Molesey, Surrey KT8 2UZ, UK

T [phone] F [phone] E [e-mail] W www.delta-controls.com

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CONTENTS

Warranty - - - - - - - - 3
Glossary - - - - - - - - 3 - 4
Product Introduction - - - - - - - - 5

Features
Sensor, Electronics - - - - - - - - 5

Software & Local Display - - - - - - - - 5 - 6

Installation
General - - - - - - - - 6
Mechanical - - - - - - - - 7
Electrical - - - - - - - - 7 - 9

Commissioning
Blind Instrument - - - - - - - - 9 -10
Multi-Drop - - - - - - - - 11
Trouble Shooting - - - - - - - - 11

Specifications - - - - - - - -
Functional, Performance 12
Physical & Drawings - - - - - - - - 13
Certified Products - - - - - - - - 14-15

Options, Spares and Maintenance - - - - - - - - 16
Re-Calibration Procedure - - - - - - - - 16
Product code - - - - - - - - 17

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WARRANTY

This instrument is guaranteed against faulty workmanship and material for a period of one year from the
date of delivery. The company undertakes to repair, free of charge, ex-works any instrument found to be
defective within the specified period provided the instrument has been used within the specification in
accordance with these instructions and has not been misused in any way. Detailed notice of such defects
and satisfactory proof thereof must be given to the company immediately after the discovery and the
goods have to be returned free of charge to the company, carefully packed and accompanied by a
detailed failure report.

HEALTH AND SAFETY

To comply with health and safety requirements, any returned instrument must be clean and safe to
handle and accompanied by a formal statement to that effect duly signed by an authorised officer of the
user company. Any instrument returned without certification will be quarantined and no action will occur
until cleared. We reserve the right to refuse to handle, and to return to the user, subject to transportation
charge, any instrument for which a declaration of safety is not received.

COPYRIGHT

Copyright © 1994 - 2007 Delta Controls Limited. All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system or transmitted in any form or by any means without the express
prior written permission of Delta Controls Limited.
Copyright © 1994 - 2007 Delta Controls Limited. All rights reserved. All software and firmware supplied
with this instrument, on disc or embedded are the sole property of Delta Controls Limited.

DISCLAIMER

Delta Controls Limited does not authorise or warrant any product for use in life support devices and/or
systems without the express written approval of an officer of the Company. All information contained
within this manual is provided in good faith as a guide only; for specific applications, Delta Controls
Limited should be contacted directly. The information contained within this manual is subject to change
without notice.

NOTE

HART® is a registered trademark of the HART Communication Foundation.
Hastelloy C® is a registered trademark of Cabot Corporation.
Monel® is a registered trademark of International Nickel Co.

GLOSSARY

Characterise Factory procedure used to calibrate the electronics so that sensor errors and

Configurators To take advantage of the extra features within a smart transmitter a "configurator" is

Damping Software function used to increase the response time of the transmitters analogue

Descriptor A sixteen character field for additional identification of the field device, this may

EEPROM Electrically erasable programmable read only memory, that retains its memory even

EMC Electro Magnetic Compatibility, the ability of a product to function without influencing

HART® Highway Addressable Remote Transducer. This protocol has become the de facto

temperature shifts are eliminated.

used. This normally allows viewing and editing of variables via a keyboard and
integral display.

output. This helps to smooth the output when there are rapid input variations.

contain its plant location, or name.

during long term power removal

any other product, or being influenced

standard for digital communications with smart field devices. The HART®
Communications Foundation is the owner of the registered trademark and provides
support for end users and developers.

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LRL Lower Range Limit (pressure): The lowest measured value (pressure) that the

transmitter can sense, governed by the sensor.

LRV Lower Range Value (pressure): Normally the lowest measured value (pressure) that

the analogue output (mA) of the transmitter can represent, but this may be reversed
with URV (pressure) for reverse analogue outputs (mA).

Master Name used to describe any system that is in control of the slave field devices, HART

can support two masters, primary and secondary.

Message A thirty two character field for additional information, name of installation engineer,

calibration technician etc.

MODEM Modulator \ Demodulator: a device that converts serial computer signals to and from

an FSK (Frequency-Shift-Keyed) format.

Multidrop This mode allows several field devices to share a common twisted pair of cables, a

total of 15 devices may use one cable.

Polling Address Unique number (1 - 15) used to identify an instrument when it is used in a multi-drop

circuit. Transmitters that are not used in a multi-drop configuration have a poll number
of zero.

Protocol A set of rules or specifications that defines the structure of a communications

language.

PV Prime Variable, in this case pressure.
Re-ranging Function that allows the transmitters analogue output to be scaled differently from the

sensors upper and lower range limits (pressure).

SV Secondary Variable, in this case temperature.
Slave Name used to describe any device that will respond when requested to by a master.
Smart A generic name used to describe any field device that can be configured from a

remote location, and shows some form of intelligence.

Span Difference between the upper and lower range values (pressure).
Sputtering A process used to bond glass and other materials to each other at a molecular level.
Tag An eight character field for identification of the transmitter, this is used in long frame

format to build the unique identifier

URL Upper Range Limit (pressure): The highest measured value (pressure) that the

transmitter can sense, governed by the sensor.

URV Upper Range Value (pressure): Normally the highest measured value (pressure) that

the analogue output (mA) of the transmitter can represent, but this may be reversed
with LRV (pressure) for reversed analogue outputs( mA).

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PRODUCT INTRODUCTION

The Delta HT Series of SMART transmitters accurately measures gauge or absolute pressure and
transmits a traditional 4-20 mA signal as well as a digital signal using the HART® protocol. The HART®
protocol gives the ability to integrate into one system, products from different manufacturers with
predictable functionality and control. HART® has become the most widely used digital communication
system for process instruments and controllers.

These transmitters complement the popular Delta 387 transmitters. Digital technology has been used to
ensure accuracy, stability and range-ability across the full temperature range. Like its smaller brother the
HT series of transmitters features a robust all stainless steel case.

The extensive use of surface-mount components and custom micro-power devices has resulted in a
transmitter that is small, light and self supporting, although pipe mounting brackets are available if
required.

In addition to the remote digital communications, the unit has, as standard, local zero and span
adjustment at the touch of a button. If more than just local span and zero are required, there is a local
display module available, the D-CAL. This can directly access more than 80% of the SMART
transmitter’s commands, for installation, commissioning and maintenance checks. The display may be
fitted within the unit with no change to the external dimensions or supplied in a small hand-held case for
repeated use when configuring blind instruments.

The transmitter is manufactured within a quality system, approved to ISO 9001:2000.

FEATURES

THE SENSOR :-

Gauge and Absolute Pressure - The preferred sensor below 10 Bar is a precision piezo-resistive
transducer, with a silicone fill and a 316 stainless steel diaphragm. Above 10 Bar the sensor is a one
piece, machined diaphragm with a sputtered thin film strain gauge. The diaphragm is specially designed
to optimise the sensor for each range. The wetted parts of the sensor (diaphragm and inlet) can be
selected from stainless steel, Monel or Hastelloy C to suit the process fluid being used. Gauge or
absolute reference can be offered on all ranges.

THE ELECTRONICS :-

The heart of the HT transmitter is an electronics module that uses surface mount technology
and a 16 bit micro-controller, supervising all functions of the transmitter and performing
continuous self checks to make sure the software is running properly.

The micro-controller takes the digital output from the sensor electronics and, using calibration
coefficients, compensates the sensor signal for linearity and local temperature. Because the actual
pressure is now digitised, any mathematical function may be applied to change the output. This allows
conversion between different engineering units to be shown and square root extraction to be applied
where required.

Any changes to the transmitter configuration are stored in EEPROM which is non volatile in the event of
power supply failure. If a power failure occurs the transmitter will restart safely and signal digitally to a
controller that a power failure has occurred.

The digital, linearised signal is fed to the output circuits. One signal is converted into a 4 to 20 mA
current, the other is a superimposed audio tone conforming to the HART® protocol.

The input and output circuits of the transmitter are fully protected against over voltage, reverse polarity
and RFI ; the local display/configurator is IP rated and protected against RFI.

THE SOFTWARE :-

The software controls all functions of the transmitter, continuous self-diagnostics, communications,
pressure calculations and display (if fitted). The firmware program is permanently stored within the
micro-controller, all calibration and run time variables are stored in EEPROM. The software has built-in
checks for sensor failure, loss of voltage reference and many other very unlikely failures. The software
also contains complex algorithms for temperature and sensor linearisation, to mathematically
characterises the sensor and electronics over its full temperature range to guarantee accuracy and
repeatability. Within the software there is also a powerful state machine which is the set of statements
that make decisions within the local configurator, and allows the transmitter to be set up as required.

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THE DISPLAY / CONFIGURATOR (“D_CAL”) :-

The Local display unit is constructed from a single stainless steel puck that when fitted gives the
transmitter a protection rating of IP 54 with the cover removed. The unit continuously shows prime
variable and units of measure in monitor mode. If current or percentage output is required, then this may
be selected on the D-CAL. The display unit also allows access to the state machine that generates a
user friendly menu with access to the internal HART® functions that are commonly used for installation
and maintenance.

To browse, edit and store information from the menu two buttons are used, CHANGE and SELECT. The
SELECT button, when held for 2 seconds, saves a selected value to EEPROM. If the selection is invalid
or out of range the transmitter will not store the change and will reply {REJECTED}.

For full detail, see the D-CAL Manual

INSTALLATION ( GENERAL )

The final accuracy of the transmitter depends to a great
extent on the proper installation of the unit and impulse
piping. Care should be taken to minimise the effects of
vibration, shock and temperature fluctuations. Care
should also be taken to make sure that the transmitter is
in a accessible position, where possible.
Before installation of the unit, ensure that the pressure
range and maximum working pressures selected are
compatible with the expected system pressure. Adequate
lengths of impulse lines, or siphons should be used to
ensure that very high temperature process media do not
come into direct contact with the unit. Precautions should
also be taken against the media freezing within the unit.
As the best location for the transmitter in relation to the process depends upon the process medium,
please consider the following points before installation.

• Keep all impulse lines as short as possible, and of the same length.

• Avoid high points in liquid and low points in gas lines.

• Use piping large enough to prevent blockage.

• Make sure there are no unaccounted static heads that will give false readings.

• Make sure that the transmitter is isolated from high process temperatures.

The 2HT is designed to be self supporting and can be mounted in any position. Brackets are, however,
available should wall or pipe mounting be required.
The pressure connection should be tightened using a 50 mm ( 2" ) AF spanner on the flats of the lower
body, and the appropriate spanner on the pipe-work connector.

DO NOT USE A COMPRESSION WRENCH ON THE 2HT BODY TO TIGHTEN THE PRESSURE
CONNECTION.

Typical Pipe Mounts for 2HT

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