BA405C intrinsically safe 2-wire 4/20mA manual set point ... · BA405C intrinsically safe 2-wire...

BA405C intrinsically safe 2-wire 4/20mA manual set point station issue 6

Issue: 617th November 2009

ul. Lechicka 14 ; 02-156 Warszawa Fax. (+48 022) 846 50 37 [email protected] Automatyka Sp. z o. o. Tel. (+48 022) 886 10 16 www.trautomatyka.pl

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1. Description

2. Operation

3. Intrinsic Safety Certification3.1 ATEX certificate3.2 FM Approval for use in the USA3.3 Safety parameters3.4 Zones, gas groups & T rating3.5 Certification label information

4. System Design for Hazardous Areas4.1 4/20mA loop using Zener barriers4.2 4/20mA loop using Galvanic

Isolators.4.3 Optional backlights

4.3.1 Separately powered backlight4.3.2 Loop powered backlight

5. Installation5.1 Location5.2 Installation procedure5.3 EMC

6. Calibration6.1 Internal display

6.1.1 Zero adjustment6.1.2 Span adjustment6.1.3 Decimal point6.1.4 Reverse action6.1.5 Calibration example6.1.6 Over & under-range

7. Maintenance7.1 Fault finding during commissioning7.2 Fault finding after commissioning7.3 Servicing7.4 Routine maintenance7.5 Guarantee7.6 Customer comments

8. Accessories8.1 Scale card.8.2 Tag strip

Appendix 1FM Approval for use in the USA

The BA405C is CE marked to show compliance with theEuropean Explosive Atmospheres Directive 94/9/EC

and the European EMC Directive 2004/108/EC

CONTENTS

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1. DESCRIPTIONThe BA405C is an intrinsically safe loop poweredset point station which enables the current flowingin a 4/20mA loop to be manually adjusted fromwithin a hazardous process area.

The main application of the BA405C is theadjustment of plant parameters. Controller setpoints, actuator positions or any variablerepresented by a 4/20mA signal may be manuallyadjusted.

The BA405C has a high resolution ten turn controlallowing accurate adjustment of the 4/20mAcurrent and a 3½ digit indicator to display the4/20mA loop current in any linear engineeringunits. Optional separately powered and looppowered display backlights are available for thedisplay.

The BA405C and the optional display backlightscomply with the European ATEX Directive 94/9/ECand have been issued with an EC-TypeExamination certificate by Notified Body ITSTesting and Certification Ltd.

For use in the USA the BA405C has intrinsic safetyand nonincendive FM Approval - see Appendix 1.

2. OPERATIONThis instruction manual describes ATEX systemdesign and installation, please refer to Appendix 1for details of the FM Approval.

Fig 1 shows a simplified block diagram of theBA405C manual set point station. The ten turncontrol knob enables the current flowing in the loopto be manually set at any value betweenapproximately 3.5 and 21mA. The outputresistance of the BA405C is very high so the loopcurrent will be unaffected by changes in the supplyvoltage.

CautionThe 4/20mA output should not be used for

critical safety applications.

The 3½ digit internal indicator can easily becalibrated on-site to show the loop current inengineering units. For example, in an applicationwhere the BA405C is being used to adjust the setpoint of a speed controller, the internal indicatormay be calibrated to display the requested speedin RPM.

Two types of optional display backlighting areavailable. The loop powered backlight producesgreen background illumination enabling the displayto be read at night or in poor lighting conditions.The separately powered backlight has a brightorange output which enhances daylight viewing.

Fig 1 Simplified block diagram of BA405C

3. INTRINSIC SAFETY CERTIFICATION

3.1 ATEX certificateThe BA405C has been issued with an EC-TypeExamination Certificate ITS03ATEX21103 byNotified Body Intertek Testing Services (ITS)confirming compliance with the European ATEXDirective 94/9/EC for Group II, Category 1 Gapparatus, EEx ia IIC T5. The instrument bearsthe Community Mark and, subject to local codes ofpractice, may be installed in any of the EuropeanEconomic Area (EEA) member countries. ATEXcertificates are also acceptable for installations inSwitzerland. This manual describes installationswhich conform with BS EN60079:Part14 ElectricalInstallation in Hazardous Areas. When designingsystems for installation outside the UK, the localCode of Practice should be consulted.

3.2 FM Approval for use in the USAPlease refer to Appendix 1 for information aboutFM intrinsic safety and nonincendive approval ofthe BA405C.

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3.3 Safety parametersThe BA405C EC-Type Examination Certificatespecifies the maximum input safety parameters forthe two 4/20mA terminals 1 and 3, and theequivalent internal capacitance and inductancethat appears between the terminals. Using theentity concept and these safety parameters,suitable Zener barriers or galvanic isolators maybe selected and the maximum permissable cableparameters calculated.

The following figures are reproduced from theATEX certificate ITS03ATEX21103

Terminals 1 and 3:(4/20mA output terminals)

Basic BA405C set point station withoutoptional loop powered display backlight.

Maximum input safety parametersUi = 30V dcIi = 200mA dcPi = 0.85W

Equivalent capacitance and inductanceCi = 40nFLi = 0.01mH

With loop powered display backlightTerminals 1 and 13(3 and 12 connected in series)



Separately powered display backlightTerminals 12 and 13



3.4 Zones, Gas Groups and T ratingThe BA405C and both the optional displaybacklights have been certified as Group II category1G apparatus, EEx ia IIC T5. When powered viaa compatable Zener barrier or galvanic isolator theBA405C manual set point station may be installedin:

Zone 0 explosive gas air mixturecontinuously present.

Zone 1 explosive gas air mixture likelyto occur in normal operation.

Zone 2 explosive gas air mixture notlikely to occur, and if it does willonly exist for a short time.

Be used with gases in groups:Group A propaneGroup B ethyleneGroup C hydrogen

Having a temperature classification of:T1 450°CT2 300°CT3 200°CT4 135°CT5 100°C

WARNING installation in Zone 0When installed in a Zone 0 potentiallyexplosive atmosphere requiring apparatusof Category 1G, the set point station shall beinstalled such that even in the event of rareincidents, an ignition source due to impactor friction between the aluminium enclosureat the rear of the instrument mounting paneland iron/steel is excluded.

3.5 Certification label informationThe ATEX certification information is shown on alabel fitted in a recess on the top outer surface ofthe enclosure.

BA405C ATEX certification label

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4. SYSTEM DESIGN FOR HAZARDOUSAREAS

4.1 4/20mA loop using Zener barriersThe required operating voltage depends on whichoptions are fitted as shown below.

Options Voltage range TerminalsBA405C 6.1 to 30V 1 & 3WithoutOptions.

BA405C with 10 to 30V 1 & 13Loop powered (3 & 12display joinedbacklight. together)

Fig 2 illustrates a typical application in which aBA405C is being used to adjust the septpoint of aspeed controller. To enable the negative side ofboth the load and the power supply to be earthed,a Zener barrier is required in series with both wiresgoing into the hazardous area.

Any Zener barrier or barriers certified by an EECapproved body to EEx ia IIC, having outputparameters equal to or less than the maximumBA405C certified input safety parameters may beused. For this type of application a 28V, 93mA0.65W (28V 300Ω) device is normally used topower the loop, plus a diode return barrier. Thesetwo devices are available as two channels in onepackage.

The maximum permitted cable parameters arethose specified on the Zener barrier certificate lessthe set point stations equivalent input capacitanceor inductance Ci & Li.

When designing the loop it is necessary toestablish that the maximum voltage drop causedby the manual set point station, both Zenerbarriers, the load and cable resistance is alwaysless than the minimum supply voltage.

Fig 2 Typical application using barriers

In this example:Minimum operating voltage of BA405C 6.1V

Maximum voltage drop caused by 28V 6.8V93mA, 0.65W Zener barrier(340Ω end-to- end resistance x 20mA)

Maximum voltage drop caused by 1.3Vdiode return barrier

Maximum voltage drop caused by 5.0V250ohm load(250ohms x 20mA)

Maximum voltage drop caused by 0.2VCable resistance(10ohms x 20mA)

______Total maximum voltage drop 19.4V

The power supply voltage must therefore be above19.4V, but below 25.5V which is the maximumworking voltage of a typical 28V Zener barrier. Ifthe optional loop powered backlight was includedin the circuit this introduces a further 3.9V drop sothat the supply voltage would have to be regulatedbetween 23.3 and 25.5 See section 4.3.2.

4.2 4/20mA loop using Galvanic IsolatorsGalvanic isolators, although more expensive thanZener barriers, do not require a high integrity earthconnection. For small systems where a highintegrity earth is not already available, the use ofgalvanic isolators often reduces the overallinstallation cost.

The example described in section 4.1 can besimplified by the use of galvanic isolators as shownin Fig 3.

Fig 3 Typical application using a galvanic isolator

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Any galvanic isolator certified EEx ia IIC by anEEC approved body with output parameters equalto or less than the maximum BA405C certifiedinput parameters may be used.

The maximum permitted cable parameters for theloop should be calculated by subtracting Ci & Li forthe BA405C from the cable parameters specifiedon the galvanic isolator certificate.

When designing the loop it is necessary toestablish that the supply voltage between terminals1 & 3 of the BA405C set point station alwaysexceeds the minimum operating voltage shown insection 4.1

4.3 Optional BacklightsThe BA405C set point station can be supplied withtwo different backlights. The loop poweredbacklight produces green background illuminationenabling the display to be read at night or in poorlighting conditions. No additional power supply, ISinterface or field wiring are required, but theminimum operating voltage drop of the set pointstation is increased to 11.1V.

Alternatively, the separately powered backlight hasa bright orange output which enhances daylightviewing, but it requires an additional IS interfaceand field wiring.

4.3.1 Separately powered backlightThis backlight is segregated from the measuringcircuit and has been certified as a separateintrinsically safe circuit.

The maximum input safety parameters are

Maximum inputUi = 28V dcIi = 159mA dcPi = 0.8W


Any Zener barrier or isolator certified EEx ia IIC byan EEC approved body which has outputparameters equal to, or less than, the maximuminput parameters specified above may be used.Most installations would use a 28V, 93mA 0.65W(28V 300Ω) device as shown in Fig 4.

The display brilliance depends upon the currentflowing through the backlight which is determinedby the supply voltage and the end-to-endresistance of the Zener barrier or output resistanceof the galvanic isolator. Brilliance will not besignificantly reduced until the current falls below20mA.

Fig 4 Separately powered backlight

The separately powered backlight requires aminimum supply voltage of 14V, The backlightcurrent can be calculated from:

Backlight current = Vsupply –14 End-to-end resistance of barrier#

# Or output resistance of galvanic isolator

Two BA405C separately powered backlights maybe powered in parallel from a single 28V 300ΩZener barrier or galvanic isolator, but the displaybrilliance will be reduced.

4.3.2 Loop powered backlightThe loop powered backlight is connected in serieswith, and powered by, the 4/20mA current from theset point station This eliminates the need for aseparate Zener barrier or galvanic isolator and foradditional wiring, thus significantly reducing theinstallation cost.

Fig 5 Loop powered backlight

Fig 5 shows how the loop powered backlightshould be connected in series with the set pointstation. Any Zener barrier or galvanic isolatorcertified EEx ia IIC by an EEC approvedcertification body may be used providing the outputsafety parameters do not exceed:

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Uo = 30V dcIo = 159mAPo = 0.8W

The maximum permitted cable parameters for theloop should be calculated by subtracting Ci & Li forthe BA405C with a loop powered backlight fromthe cable parameters specified on the Zenerbarrier or galvanic isolator certificate.

Inclusion of the loop powered backlight increasesthe minimum operating voltage of the BA405C to10V

5. INSTALLATION

5.1 LocationThe BA405C is housed in a robust aluminiumenclosure with a polyester front panel and a Norylbezel. The front panel provides IP65 protectionand a gasket seals the joint between theinstrument and the panel. The BA405C may beinstalled in any panel providing the environmentallimits shown in the specification are not exceeded.The front of the instrument should not be cleanedwith, or exposed to solvents.

Please refer to BEKA associates if high vibration isanticipated.

Fig 6 shows the enclosure dimensions and therecommended panel cut-out sizes.

5.2 Installation Procedurea. Insert the BA405C set point station into the

panel aperture from the front. Ensure thatthe gasket is correctly positioned under thebezel.

b. Fix two panel mounting clips to oppositesides of the instrument and tighten until theindicator is secured as shown in Fig 7.

c. Connect the panel wiring to the rear terminalblock as shown in Fig 6. To simplifyinstallation, the terminals are removable sothat the panel wiring can be completedbefore the instrument is installed.

5.3 EMCThe BA405C complies with the requirements of theEuropean EMC Directive. For specified immunityall wiring should be in screened twisted pairs withthe screen earthed within the safe area. Theenclosure may be earthed locally by securing a tagunder one of the rear panel corner fixing screws,

Fig 6 BA405C Dimensions

Fig 7 Fitting panel mounting clips

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6. CALIBRATIONThe BA405C output currrent does not require anycalibration, the front panel multi-turn control willalways adjust the output current betweenapproximately 3.5 and 21mA.

6.1 Internal displayThe internal display requires calibrating so that the4/20mA loop current is shown in the requiredengineering units.

The BA405C will be supplied with the displaycalibrated as requested at time of ordering. Ifcalibration is not requested, the display will be setto show 00.0 with 4.000mA loop current and 100.0with 20.000mA loop current.

The display is calibrated by plug-in links and twomulti-turn potentiometers which are accessiblethrough holes in the rear panel. Togain access to the links the rear panel must beremoved as shown in Fig 8.

For maximum accuracy the display should becalibrated using a traceable current measuringdevice with an accuracy greater than 4µA.

Fig 8 Removal of rear panel

6.1.1 Zero adjustmentZero is defined as the number displayed when theBA405C output is 4.000mA, and may adjustedbetween -1000 and 1000. The zeropotentiometer has two ranges 0 to 500 and 500 to1000. Tthe polarity of the zero is defined by theposition of the suppression / elevation links.

Fig 9 shows the position of the zero links and zeropotentiometer.

Suppression / elevation linksElevation Positive zero 0 to 1000

or Suppression Negative zero 0 to -1000

Zero link0 to 500

or 500 to 1000

6..1.2 Span adjustmentSpan is defined as the difference between thenumber displayed at 4.000mA and the numberdisplayed at 20.000mA output. The spanpotentiometer has four ranges defined by the spanlinks, and may be adjusted to any number between0 and 1999.Fig 9 shows the position of the span links and spanpotentiometer.

Span links000 to 500

or 500 to 1000or 1000 to 1500or 1500 to 1999

6.1.3 Decimal pointA dummy decimal point may be displayed betweenany of the four digits. The position or absence ofthis decimal point is determined bythe position of the decimal point link shown in Fig9. When calculating the required span and zerosetting the decimal point should be ignored.

6.1.4 Reverse actionNormally the BA405C display increases as theloop current increases, but this can be reversed.Please contact BEKA associates for details.

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6.1.5 Calibration exampleA BA405C set point station is required to display25.0 with a 4.000mA output and 115.0 with at20.000mA output.

i.e. A zero of positive 250 Ignoring decimalpoint.A span of 900A dummy decimal point in position 00.0

The following adjustments are required:

Step 1 The BA405C is required to display apositive zero therefore thesuppression / elevation links should beput in the elevation position.

Step 2 The required zero is 250, therefore thezero link should be put in the 0 to 500position.

Step 3 The required span is 900, therefore thespan links should be placed in the 500 to1000 position.

Step 4 A dummy decimal point is requiredbetween the least two significant digits,therefore the decimal point link should beplaced in the 00.0 position.

Step 5 Adjust the BA405C front panel controluntil the output current measured byexternal ammeter is 4.000mA. The zeropotentiometer at the rear of the BA405Cshould then be adjusted until theBA405C displays 25.0

Step 6 Adjust the BA405C front panel controluntil the external current measured by anexternal ammeter is 20.000mA. Thespan potentiometer at the rear of theBA405C should then be adjusted untilthe BA405C displays 115.0

Step 7 Repeat steps 5 and 6 until bothcalibration points are correct. The spanand zero controls are almostindependent so it should only benecessary to repeat each adjustmenttwice.

Fig 9 Position of calibration plug-in links and potentiometers

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6.1.6 Over and under-rangeThe BA405C can display numbers between -1999 and 1999. If this range is exceeded the threeleast significant digits will be blanked. Under-range is indicated by -1 and over-range by 1.

7. MAINTENANCE

7.1 Fault finding during commissioningIf a BA405C set point station fails to functionduring commissioning the following procedureshould be followed:

Symptom Cause SolutionNo loop Incorrect Check wiringcurrent wiring or no and power

power supply supply polarity

BA405C Positive The display has beendisplays 1 over-range incorrectly calibrated

& is trying to show anumber greater than1999.

BA405C Negative The display has beendisplays -1 over-range incorrectly calibrated

& is trying to show anumber less than-1999.

Unstable Insufficient Check that voltageloop supply between terminalscurrent voltage 1 & 3 is greater than

6.1V, or 10V betweenterminals 1 & 13 if aloop poweredbacklight is fitted.

Unstable Power supply Reduce rippledisplay has voltage.

ripple

7.2 Fault finding after commissioning

ENSURE PLANT SAFETY BEFORESTARTING MAINTENANCE

Live maintenance is permitted on intrinsicallysafe equipment installed in a hazardous area,

but only certified test equipment should beused unless a gas clearance certificate is

available.

If a BA405C fails after it has been functioningcorrectly, the following procedure should befollowed:

Symptom Cause SolutionNo loop Wiring or power Check wiringcurrent supply fault and power

supply

Unstable Insufficient Check that voltageloop supply between terminalscurrent voltage 1 & 3 is greater than

6.1, or 10V betweenterminals 1 & 13 if fittedwith a loop poweredbacklight.

Unstable Power supply Reduce rippledisplay has developed

voltage ripple

If this procedure does not reveal the cause of thefault, it is recommended that the BA405C manualset point station is replaced with a spareinstrument.

7.3 ServicingWe recommend that faulty BA405C set pointstations are returned to BEKA associates or to ourlocal agent for repair.

7.4 Routine maintenenceThe mechanical and electrical condition of theinstrument should be regularly checked. Initiallyannual inspections are recommended, but theinspection frequency should be adjusted to suit theenvironmental conditions.

7.5 GuaranteeSet point stations which fail within the guaranteeperiod should be returned to BEKA associates orour local agent. It is helpful if a brief description ofthe fault symptoms is provided.

7.6 Customer commentsBEKA associates is always pleased to receivecomments from customers about our products andservices. All communications are acknowledgedand whenever possible, suggestions areimplemented.

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8. ACCESSORIES

8.1 Scale cardThe BA405C has a window below the control knobto accommodate a scale card. Set point stationscan be supplied with a printed scale card showingany units specified at the time of ordering e.g. oC,mBar, RPM. If a printed scale card is notrequested, a blank card will be supplied.

Scale cards can easily be marked on site asfollows:

a. Remove the rear terminal block(s) and therear panel as shown in Fig 8.

b. Remove the end cap from the front panelcontrol knob using a thin bladed screwdriver.This will reveal a screw collet which securesthe control knob to the shaft. Loosen thecollet by turning the brass split screwhead anticlockwise and then carefully pull the controlknob from the shaft.

c. Pull the electronic assembly from the rear ofthe enclosure.

d. Remove the blank scale card(s) and markwith the required legend. Replace scalecard(s) taking care to align them within thefront panel window.

e. Slide the electronic assembly into the rear ofthe enclosure and carefully guide the controlshaft through the front panel seal. Replacethe rear panel and terminals.

f. Replace the control knob and tighten thecollet screw. Finally push the knob end capinto place.

8.2 Tag stripThe BA405C can be supplied with a thermallyprinted tag strip on the rear panel. This tag strip isnot visible from the front of the instrument afterinstallation.

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APPENDIX 1FM Approval for use in the USA

A1.0 Factory Mutual ApprovalFor installation in the USA the BA405C has FMIntrinsic Safety and FM Nonincendive approval,project identification 3026081. Copies of theCertificate of Compliance are available from BEKAassociates sales office and www.beka.co.uk.

A2.1 Intrinsic safety approvalThe BA405C is approved to the FM Class 3610intrinsic safety standard for use in indoor andoutdoor hazardous (classified) locations.Installations must comply with BEKA associatesControl Drawing CI405-27 which is attached to thisAppendix, ANSI/ISA RP12.06.01 ‘Installation ofIntrinsically safe Systems for Hazardous(Classified) Locations’ and with the NationalEl;ectrical Code ANSI/NFPA70.

The BA405C has a T4 rating at ambienttemperatures up to 60 oC and may be used withthe following gases:

Intrinsic SafetyDivision 1 or 2

Class I Group A & B Group C Group D

Zone 0, 1 or 2Class 1 Group IIC Group IIB Group IIA

The FM entity parameters are similar to the ATEXparameters. The intrinsically safe systems shownin this manual may therefore be used forinstallations in the USA providing the Zenerbarriers or galvanic isolators are FM Approved. Allinstallations must comply with BEKA associatesControl Drawing CI405-27.

A2.2 Nonincendive approvalThe BA405C is FM Class 3611 nonincendiveapproved allowing it to be installed in Division 2indoor and outdoor hazardous (classified)locations without the need for Zener barriers orgalvanic isolators. US installations must complywith the BEKA associates Control Drawing CI405-27, which is attached to this Appendix, and withthe National Electrical Code ANSI/NFPA70.

The BA414DF has a T4 rating at ambienttemperatures up to +60oC and may be used withthe following gases:

NonincendiveDivision 2

Class I Group A & B Group C Group D

Zone 2Class I Group IIC Group IIB Group IIA

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ul. Lechicka 14 ; 02-156 Warszawa Fax. (+48 022) 846 50 37 [email protected] Automatyka Sp. z o. o. Tel. (+48 022) 886 10 16 www.trautomatyka.pl

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