Vega MINITRAC 31 Installation and operating instructions

Installation & Maintenance Instructions
MINITRAC 31
4 … 20 mA/HART - four-wire
Radiation-based sensor for density measurement
Reading Office
Cutbush Park, Danehill, Lower Earley,
Reading, Berkshire. RG6 4UT. UK.
Tel: [phone]
Email: [email protected]
Aberdeen Office
Unit 6 Airside Business Park, Kirkhill Industrial Estate,
Dyce, Aberdeen. AB21 0GT. UK.
Tel: [phone]
Email: [email protected]
Internet: www.able.co.uk
e-procurement: www.247able.com
Registered in England No: 01851002
VAT No: GB 417 2481 61

2
Contents
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
Contents
1 About this document
1.1 Function ........................................................................................................................... 4
1.2 Target group ..................................................................................................................... 4
1.3 Symbolism used............................................................................................................... 4
2 For your safety
2.1 Authorised personnel ....................................................................................................... 5
2.2 Appropriate use................................................................................................................ 5
2.3 Warning about incorrect use............................................................................................. 5
2.4 General safety instructions............................................................................................... 5
2.5 CE conformity................................................................................................................... 6
2.6 NAMUR recommendations .............................................................................................. 6
2.7 Environmental instructions ............................................................................................... 6
3 Product description
3.1 Conguration.................................................................................................................... 7
3.2 Principle of operation........................................................................................................ 8
3.3 Packaging, transport and storage................................................................................... 10
3.4 Accessories and replacement parts ............................................................................... 10
3.5 Corresponding source container.................................................................................... 11
4 Mounting
4.1 General instructions ....................................................................................................... 13
4.2 Mounting instructions ..................................................................................................... 14
5 Connecting to power supply
5.1 Preparing the connection ............................................................................................... 19
5.2 Connection-Density,massowratemeasurement....................................................... 22
5.3 Connection - Level detection.......................................................................................... 24
6 Set up with the display and adjustment module
6.1 Insert display and adjustment module............................................................................ 26
6.2 Adjustment system......................................................................................................... 27
6.3 Parameter adjustment - Level measurement.................................................................. 27
6.4 Parameter adjustment - Density measurement .............................................................. 32
6.5 Parameter adjustment - Level detection ......................................................................... 44
6.6 Parameter adjustment - X-ray alarm............................................................................... 53
6.7 Parameter adjustment/Real value correction.................................................................. 55
6.8 Saving the parameter adjustment data........................................................................... 57
7 Setup with PACTware
7.1 Connect the PC.............................................................................................................. 59
7.2 Parameter adjustment with PACTware............................................................................ 60
7.3 Saving the parameter adjustment data........................................................................... 61
8 Set up with other systems
8.1 DD adjustment programs ............................................................................................... 62
8.2 Field Communicator 375, 475 ........................................................................................ 62
9 Diagnostics and service
9.1 Maintenance .................................................................................................................. 63
9.2 Status messages............................................................................................................ 63
9.3 Rectify faults................................................................................................................... 67

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Contents
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
9.4 Exchanging the electronics module................................................................................ 68
9.5 Software update ............................................................................................................. 69
9.6 How to proceed in case of repair.................................................................................... 69
10 Dismounting
10.1 Dismounting steps.......................................................................................................... 71
10.2 Disposal ......................................................................................................................... 71
11 Supplement
11.1 Technical data ................................................................................................................ 72
11.2 Dimensions .................................................................................................................... 77
Safety instructions for Ex areas
PleasenotetheEx-specicsafetyinformationforinstallationandop-
eration in Ex areas. These safety instructions are part of the operating
instructions manual and come with the Ex-approved instruments.
Editing status: 2013-04-29

4
1 About this document
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
1 About this document
1.1 Function
This operating instructions manual provides all the information you
need for mounting, connection and setup as well as important instruc-
tionsformaintenanceandfaultrectication.Pleasereadthisinforma-
tion before putting the instrument into operation and keep this manual
accessible in the immediate vicinity of the device.
1.2 Target group
This operating instructions manual is directed to trained specialist
personnel.The contents of this manual should be made available to
these personnel and put into practice by them.
1.3 Symbolism used
Information, tip, note
This symbol indicates helpful additional information.
Caution: If this warning is ignored, faults or malfunctions can result.
Warning: If this warning is ignored, injury to persons and/or serious
damage to the instrument can result.
Danger: If this warning is ignored, serious injury to persons and/or
destruction of the instrument can result.
Ex applications
This symbol indicates special instructions for Ex applications.
• List
The dot set in front indicates a list with no implied sequence.
→ Action
This arrow indicates a single action.
1 Sequence
Numbers set in front indicate successive steps in a procedure.
Battery disposal
This symbol indicates special information about the disposal of bat-
teries and accumulators.

5
2 For your safety
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
2 For your safety
2.1 Authorised personnel
All operations described in this operating instructions manual must
be carried out only by trained specialist personnel authorised by the
plant operator.
During work on and with the device the required personal protective
equipment must always be worn.
2.2 Appropriate use
The MINITRAC 31 is a sensor for density measurement and level
detection.
Youcannddetailedinformationontheapplicationrangeinchapter
"Product description".
Operational reliability is ensured only if the instrument is properly
usedaccordingtothespecicationsintheoperatinginstructions
manual as well as possible supplementary instructions.
2.3 Warning about incorrect use
Inappropriate or incorrect use of the instrument can give rise to
application-specichazards,e.g.vesseloverllordamagetosystem
components through incorrect mounting or adjustment.
2.4 General safety instructions
This is a state-of-the-art instrument complying with all prevailing
regulations and guidelines.The instrument must only be operated in a
technicallyawlessandreliablecondition.Theoperatorisresponsible
for the trouble-free operation of the instrument.
During the entire duration of use, the user is obliged to determine the
compliance of the necessary occupational safety measures with the
current valid rules and regulations and also take note of new regula-
tions.
The safety instructions in this operating instructions manual, the na-
tional installation standards as well as the valid safety regulations and
accident prevention rules must be observed by the user.
For safety and warranty reasons, any invasive work on the device
beyond that described in the operating instructions manual may be
carried out only by personnel authorised by the manufacturer. Arbi-
traryconversionsormodicationsareexplicitlyforbidden.
The safety approval markings and safety tips on the device must also
be observed.
This measuring system uses gamma rays.Therefore take note of the
instructions for radiation protection in chapter "Product description".
All work on the source container may only be carried out under the
supervisionofaqualiedradiationprotectionocer.

6
2 For your safety
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
2.5 CE conformity
ThedevicefulllsthelegalrequirementsoftheapplicableECguide-
lines.ByaxingtheCEmarking,VEGAconrmssuccessfultesting
of the product.
Only with class A instruments:
The device is a class A instrument designed for use in an industrial
environment.Whenusedinadierentenvironment,e.g.,inaliving
area, the electromagnetic compatibility must be ensured by the user.
If necessary, suitable screening measures against conducted and
emitted disturbances must be taken.
Youcanndtheconformitycerticateinthedownloadsectionunder
www.vega.com.
2.6 NAMUR recommendations
NAMUR is the automation technology user association in the process
industry in Germany. The published NAMUR recommendations are
acceptedasthestandardineldinstrumentation.
ThedevicefulllstherequirementsofthefollowingNAMURrecom-
mendations:
• NE 21 – Electromagnetic compatibility of equipment
• NE 43 – Signal level for malfunction information from measuring
transducers
• NE53–Compatibilityofelddevicesanddisplay/adjustment
components
• NE107–Self-monitoringanddiagnosisofelddevices
For further information see www.namur.de.
2.7 Environmental instructions
Protection of the environment is one of our most important duties.
That is why we have introduced an environment management system
with the goal of continuously improving company environmental pro-
tection.Theenvironmentmanagementsystemiscertiedaccording
to DIN EN ISO 14001.
Pleasehelpusfulllthisobligationbyobservingtheenvironmental
instructions in this manual:
• Chapter "Packaging, transport and storage"
• Chapter "Disposal"

7
3 Product description
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
3 Product description
3.1 Conguration
Thenameplatecontainsthemostimportantdataforidenticationand
use of the instrument:
2
1
9
9
4
5
3
6
7
8
Fig. 1: Layout of the type label (example)
1 Instrument version
2 Product code
3 Electronics
4 Protection rating
5 Ambient temperature
6 Hardware and software version
7 Order number
8 Serial number of the instrument
9 ID numbers, instrument documentation
With the serial number of the instrument on the type label you have
access to the following data on our homepage:
• Article number of the instrument (HTML)
• Delivery date (HTML)
• Order-specicinstrumentfeatures(HTML)
• Operating instructions at the time of shipment (PDF)
• Order-specicsensordataforanelectronicsexchange(XML)
• Testcerticate"MeasuringAccuracy"(PDF)
For this purpose, move to www.vega.com and "VEGA Tools".
As an alternative, you have access to these data via your Smart-
phone:
• Download the Smartphone-App "VEGA Tools" from the "Apple
App Store " or the "Google Play Store"
• Scan the Data-Matrix-Code on the type label of the instrument or
• Enter the serial number manually into the App
This operating instructions manual applies to the following instrument
versions:
• Hardware from 1.0.4
• Software from 1.4.2
• Modicationstatus,electronicsasof-01
Type plate
Serial number
Scope of this operating
instructions manual

8
3 Product description
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
Theinstrumentisavailableindierentelectronicsversions.Eachver-
sioncanbeidentiedviatheproductcodeonthetypelabel:
• Standard electronics type PT30E-XX
The scope of delivery encompasses:
• Radiation-based sensor
• Documentation
– this operating instructions manual
– Operating instructions manual "Display and adjustment mod-
ule" (optional)
– Ex-specic"Safety instructions" (with Ex versions)
– ifnecessary,furthercerticates
3.2 Principle of operation
The instrument is suitable for applications in liquids and bulk solids in
vesselsunderdicultprocessconditions.Thereareapplicationpos-
sibilities in nearly all areas of industry.
The measured value is detected contactlessly right through the vessel
wall.Neitheraprocessttingnoravesselopeningarerequired.The
instrument is thus ideal for retro installation.
Theinstrumentcanbeusedformanydierentmeasuringtasks.Apart
from the main applications such as density measurement and level
detection, the MINITRAC 31 can also detect residues and the mass
owrateinconjunctionwithaowmeter.
Electronics versions
Scope of delivery
Application area

9
3 Product description
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
12
3
4
Fig. 2: MINITRAC 31 - Application possibilities
1 Level measurement - Residue detection
2 Point level detection
3 Density measurement
4 Massowmeasurement
Further application possibilities are also the use as X-ray alarm or real
value correction.
If X-ray alarm is selected, the instrument detects radiation from exter-
nal sources. Possible external radiation sources can be, for example,
a weld joint test in a neighbouring facility or other radiation-based
instruments.
When the instrument operates as real value correction it transmits the
real value to correct another radiation-based sensor.The measure-
ment can thus be adapted perfectly to the situation in the vessel.
In radiation-based measurement, a Caesium-137 or Cobalt-60 iso-
tope emits focussed gamma rays that are attenuated when penetrat-
ing the tube wall and the medium.The NaI detector on the opposite
side, on a pipeline for example, receives the radiation. The intensity
of the radiation is dependent on the density of the measured media.
The measuring principle has proven to be very reliable in conjunction
with extreme process conditions because it measures contactlessly
from outside through the tube wall. The measuring system ensures
Functional principle

10
3 Product description
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
maximum safety, reliability and plant availability independent of the
medium and its properties.
3.3 Packaging, transport and storage
Your instrument was protected by packaging during transport. Its
capacity to handle normal loads during transport is assured by a test
based on ISO 4180.
The packaging of standard instruments consists of environment-
friendly, recyclable cardboard. For special versions, PE foam or PE
foil is also used. Dispose of the packaging material via specialised
recycling companies.
Transport must be carried out under consideration of the notes on the
transport packaging. Nonobservance of these instructions can cause
damage to the device.
The delivery must be checked for completeness and possible transit
damage immediately at receipt. Ascertained transit damage or con-
cealed defects must be appropriately dealt with.
Up to the time of installation, the packages must be left closed and
stored according to the orientation and storage markings on the
outside.
Unless otherwise indicated, the packages must be stored only under
the following conditions:
• Not in the open
• Dry and dust free
• Not exposed to corrosive media
• Protected against solar radiation
• Avoiding mechanical shock and vibration
• Storage and transport temperature see chapter "Supplement -
Technical data - Ambient conditions"
• Relative humidity 20 … 85 %
3.4 Accessories and replacement parts
The display and adjustment module PLICSCOM is used for measured
value indication, adjustment and diagnosis. It can be inserted into the
sensor or the external display and adjustment unit and removed at
any time.
Youcanndfurtherinformationintheoperatinginstructions"Display
and adjustment module PLICSCOM" (Document-ID 27835).
TheinterfaceadapterVEGACONNECTenablestheconnectionof
communication-capable instruments to the USB interface of a PC. For
parameter adjustment of these instruments, an adjustment software
suchasPACTwarewithVEGA-DTMisrequired.
Youcanndfurtherinformationintheoperatinginstructions"Interface
adapter VEGACONNECT" (Document-ID 32628).
Packaging
Transport
Transport inspection
Storage
Storage and transport
temperature
PLICSCOM
VEGACONNECT

11
3 Product description
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
VEGADIS81isanexternaldisplayandadjustmentunitforsensors
with single or double chamber housing.
For the double chamber housing there is also an interface adapter for
VEGADIS81required.
Youcanndfurtherinformationintheoperatinginstructions"VE-
GADIS 81" (Document-ID 43814).
TheVEGADIS62issuitableformeasuredvalueindicationofsensors.
It is looped into the 4 … 20 mA/HART signal cable.
Youcanndfurtherinformationintheoperatinginstructions"VE-
GADIS 62" (Document-ID 36469).
The electronics module PT30E.XX is a replacement part for radiation-
based sensors MINITRAC 31.
TheelectronicsmodulecanonlybeexchangedbyVEGAservice
technician.
3.5 Corresponding source container
A radioactive isotope in a suitable source holder is the prerequisite for
a radiation-based measurement setup.
The handling of radioactive material is regulated by law. The radiation
protection rules of the country in which the system is operated apply
rstandforemost.
In Germany, for example, the current radiation protection ordinance
(StrlSchV)basedontheAtomicEnergyLaw(AtG)applies.
The following points are important for measurement with radiation-
based methods:
A handling permit is required for operation of a system using gamma
rays.Thispermitisissuedbytherespectivegovernmentoceorthe
responsibleauthority(inGermany,forexample,ocesforenviron-
mental protection, trade supervisory boards, etc.)
Youcanndfurtherinstructionsintheoperatinginstructionsmanual
of the source container.
When handling a radioactive source, unnecessary radiation exposure
must be avoided. An unavoidable radiation exposure must be kept as
low as possible.Take note of the following three important measures:
VEGADIS 81
External indicating unit
Electronics module
Handling permit
General instructions for
radiation protection

12
3 Product description
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
1 2 3
Fig. 3: Measures for protection against radioactive radiation
1 Shielding
2 Time
3 Distance
Shielding - Provide good shielding between the radioactive source
and yourself as well as all other persons. Special source containers
(e.g.VEGASOURCE)aswellasallmaterialswithhighdensity(e.g.
lead,iron,concrete,etc.)provideeectiveshielding.
Time: Stay as short a time as possible in radiation exposed areas.
Source:Your distance to the source should be as large as possible.
The local dose rate of the radiation decreases in proportion to the
square of the distance to the radiation source.
Theplantoperatormustappointaradiationsafetyocerwiththe
necessary expert knowledge. He is responsible that the radiation
protection ordinance is maintained and that all radiation protection
measures are implemented.
Control areas are areas in which the local dose rate exceeds a certain
value.Onlypersonswhoundergoocialdosemonitoringareallowed
intothesecontrolareas.Youcanndtherespectivelyvalidlimitvalues
for control areas in the guideline of the respective authority (in Ger-
many, for example, the radiation protection ordinance).
We are at your disposal for further information concerning radiation
protection and regulations in other countries.
Radiationsafetyocer
Control area

13
4 Mounting
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
4 Mounting
4.1 General instructions
The source container is part of the measuring system. In case the
source container is already equipped with an active isotope, the
source container must be locked before mounting.
Danger:
Before mounting; make sure that the source is securely closed. Use
a padlock to secure the source container in the closed condition and
prevent it from being inadvertently opened.
Protect your instrument through the following measures against
moisture penetration:
• Use the recommended cable (see chapter "Connecting to power
supply")
• Tighten the cable gland
• Loop the connection cable downward in front of the cable gland
This applies particularly to:
• outdoor mounting
• installations in areas where high humidity is expected (e.g. through
cleaning processes)
• installations on cooled or heated vessels
Make sure that all parts of the instrument exposed to the process are
suitable for the existing process conditions.
These are mainly:
• Active measuring component
• Processtting
• Process seal
Process conditions are particularly:
• Process pressure
• Process temperature
• Chemical properties of the medium
• Abrasionandmechanicalinuences
Youcanndthespecicationsinchapter"Technical data" and on the
nameplate.
In the case of instrument housings with self-sealing NPT threads, it is
not possible to have the cable entries screwed in at the factory. The
openings for the cable glands are therefore covered with red protec-
tive caps as transport protection.
Prior to setup you have to replace these protective caps with ap-
proved cable glands or close the openings with suitable blind plugs.
The suitable cable glands and blind plugs come with the instrument.
Switchosource
Protection against mois-
ture
Suitability for the process
conditions
Protective caps

14
4 Mounting
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
4.2 Mounting instructions
Note:
During the planning stage, our specialists will analyse the conditions
of the measuring point and dimension the source (isotope) accord-
ingly.
Yougeta"SourceSizing"documentspecifyingtherequiredsource
activity and containing all relevant mounting information for your
measuring point.
Youmustfollowtheinstructionsofthis"SourceSizing"documentin
addition to the following mounting instructions.
The following mounting information is applicable as long as there is
nothingelsespeciedinthe"SourceSizing"document.
Youcanndinformationonprotectivebarriersandthemounting
of the corresponding source container in the operating instructions
manualofthesourcecontainer,e.g.VEGASOURCE.
You can mount the MINITRAC 31 in any position. If you have ordered
your instrument with a lead cover as a protection against ambient
radiation (optionally), the the sensor is shielded laterally against X-ray
radiation. In this case, the radiation can only penetrate frontally.
Fasten the sensors in such a way that they cannot fall out of the
holder.
Direct the exit angle of the source container to the MINITRAC 31.
Mount the source container as close as possible to the vessel. If there
are gaps, secure the area with a safety fence and protective grating
so that no one can reach into the dangerous area.
Caution:
Makesurethatthetubeisalwayscompletelylled.Mainlyinhorizon-
tally arranged tube measuring distances, air bubbles or buildup in
thetubecaninuencethemeasuringresult.Measurementshouldbe
preferably through the centre of the tube.
1
2
Fig. 4: Installation on a horizontal pipeline
1 Air bubbles
2 Buildup
Installation position

15
4 Mounting
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
Density measurement
A density and concentration measurement is possible on pipelines
and vessels. The accuracy of the measurement increases in propor-
tion to the radiated length (L) of medium.This is particularly important
in the case of products with low density or small tube diameters.
Therearedierentwaystoincreasetheradiatedlength(L)ofthe
medium.
L
L
L
1
4
a
b
2
3
Fig. 5: Installation possibilities - Density measurement or concentration meas-
urement
1a Direct radiation - Horizontal mounting
1b Direct radiation - Vertical mouting or when the lead cover is used as protec-
tion against ambient radiation
2 Inclined radiation for extention of the radiated length (L)
3 Extension of the radiated length (L) by adding a tube angle piece as meas-
uring distance
4 Integrated lead cover as protection against ambient radiation - the instru-
ment is hence shielded laterally

16
4 Mounting
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
Withdensitymeasurement,theradiationdierencewithdiering
density is very low. Especially with small tube diameters, the change
is negligible.
Therefore it is important to shield from interfering X-ray radiation. To
protect the instrument against X-ray radiation, it can be be equipped
withanoptionalleadring.Alaterretrottingoftheleadringisnot
possible.
Massowrate
ThemassowratecanbedeterminedwiththeMINITRAC31in
conjunctionwithaowmeter.
1
2
Fig.6:Massowratemeasurement
1 Flow meter
2 MINITRAC 31
Point level detection
Forleveldetection,thesensorisgenerallymountedhorizontallyatthe
height of the requested limit level. Make sure that there are no struts
or reinforcements at this position in the vessel.
Direct the exit beam of the source container exactly towards the
measuring range of MINITRAC 31.

17
4 Mounting
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
3
2
1
Fig. 7: Mounting position - level detection
1 Mounting horizontal
2 Mounting vertical
3 Mounting horizontally, at right angles to container
Level measurement - Residue detection
The MINITRAC 31 can be used for residue detection, e.g. in storage
tanks for high-cost liquids. For this purpose, the instrument must be
mounted at the lowest point of the vessel.

18
4 Mounting
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
Fig. 8: Level measurement - Residue detection on a storage tank
If the max. ambient temperature is exceeded, you must take suitable
measures to protect the instrument against overheating.
You can protect the instrument by providing a suitable insulation
against the heat or mounting the instrument further away from the
heat source.
Make sure these measures are taken into account already in the plan-
ning stage. If you want to carry out such measures later on, contact
our specialists to ensure that the accuracy of the application is not
impaired.
Ifthesemeasuresarenotsucienttomaintainthemax.ambient
temperature, you could consider using the water cooling system we
oerforMINITRAC31.
The water cooling must also be included in the calculations for the
measuring point. Contact our specialists regarding the dimensioning
of the water cooling.
Protection against heat

19
5 Connecting to power supply
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
5 Connecting to power supply
5.1 Preparing the connection
Always keep in mind the following safety instructions:
• Connect only in the complete absence of line voltage
• If overvoltage surges are expected, overvoltage arresters should
be installed
In this case, the instrument is designed in protection class II.To main-
tain this protection class, it is absolutely necessary that the ground
conductor be connected to the internal ground terminal.Take note of
the general installation regulations.
Supply voltage and current signal are carried on separate connection
cables if reliable separation is required. The supply voltage range can
dierdependingontheinstrumentversion.
Thedataforpowersupplyarespeciedinchapter"Technical data".
For power supply, an approved installation cable with PE conductor is
required.
The 4 … 20 mA current output is connected with standard two-wire
cable without screen. If electromagnetic interference is expected
which is above the test values of EN 61326-1 for industrial areas,
screened cable should be used.
Use cable with a round wire cross section. An outer cable diameter
of6…12mm(0.24…0.47in)ensuresthesealeectofthecable
entry.Ifcablewithadierentdiameterorwirecrosssectionisused,
exchange the seal or use an appropriate cable connection. Free cable
glandshavensucientprotectionagainstmoistureandmustbe
replaced by blind stoppers.
Generally provide all unused cable entries with suitable blind plugs.
The thin foam rubber wahsers int he cable glands are only used as
dust cover during trasport.
In the case of instrument housings with self-sealing NPT threads, it
is generally not possible to have the cable glands screwed in at the
factory. The openings for the cable glands are therefore covered with
red protective caps as transport protection.
You have to replace these protective caps with approved cable glands
beforesetuporcoverthemwithsuitablellerplugs.Unusedcable
glandsdonotprovidesucientprotectionagainstmoistureandmust
bereplacedwithllerplugs.
The suitable cable glands and blind plugs come with the instrument.
If screened cable is necessary, connect the cable screen on both
ends to ground potential. In the sensor, the screen must be connected
directly to the internal ground terminal.The ground terminal on the
outside of the housing must be connected to the potential equalisa-
tion (low impedance).
Safety instructions
Voltage supply via mains
voltage
Select connection cable
Cable entry
Cable gland ½ NPT
Cable screening and
grounding

20
5 Connecting to power supply
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
If potential equalisation currents are expected, the connection on the
processing side must be made via a ceramic capacitor (e. g. 1 nF,
1500V).Thelow-frequencypotentialequalisationcurrentsarethus
suppressed,buttheprotectiveeectagainsthighfrequencyinterfer-
ence signals remains.
Warning:
Signicantpotentialdierencesexistinsidegalvanizationplantsas
well as on vessels with cathodic corrosion protection. Considerable
equalisationcurrentscanowoverthecablescreenifthescreenis
grounded on both ends.
To avoid this in such applications, the cable screen must be connect-
ed to ground potential only at one end (in the switching cabinet).The
cable screen must not be connected to the internal ground terminal in
the sensor and the outer ground terminal on the housing must not be
connected to the potential equalisation!
Information:
The metal parts of the instrument are conductively connected with
the inner and outer ground terminal on the housing.This connection
is either a direct metallic connection or, in case of instruments with
external electronics, a connection via the screen of the special con-
nection cable.
Youcanndspecicationsonthepotentialconnectionsinsidethe
instrument in chapter "Technical data".
The voltage supply and signal output are connected via the spring-
loaded terminals in the housing.
The connection to the display and adjustment module or to the inter-
face adapter is carried out via contact pins in the housing.
Proceed as follows:
The procedure applies to instruments without explosion protection.
1. Unscrew the big housing cover
2. Loosen compression nut of the cable entry
3. Remove approx. 10 cm (4 in) of the cable mantle, strip approx.
1 cm (0.4 in) of insulation from the ends of the individual wires
4. Insert the cable into the sensor through the cable entry
Connection technology
Connection procedure