INTRINSICALLY SAFE AMPLIFIER Type 2506 Reference Manual IS Amplifiers/2506... · STRAINSTALL U.K. LTD. INTRINSICALLY SAFE AMPLIFIER Type 2506 Reference Manual Strainstall Document

STRAINSTALL U.K. LTD.

INTRINSICALLY SAFE AMPLIFIERType 2506

Reference Manual

Strainstall Document Ref: #11457

Strainstall U.K. Ltd.Denmark RoadCowesIsle of WightPO31 7TB

STRAINSTALL U.K. LTD.

INTRINSICALLY SAFE AMPLIFIERType 2506

Reference Manual

Strainstall Document Ref: #11457

Revision History

Issue: 1 2 3 4 5Date: May 2001 June 2001 Nov 2001 Oct 2002Author: JP JC/JP JC/JP CE/JPApproved:Comments: Initial issue Clarification Barrier info.

+ fig.5Drg.up-issuesee appendix

©2001 STRAINSTALL U.K. LIMITED.

The information contained in this document may be used only for the intended purpose and by the intendedrecipient. It must not be divulged to third parties or reproduced in whole or in part without the express writtenpermission of STRAINSTALL U.K. LIMITED.

Strainstall UK is a member of the Strainstall Group

Strainstall UK LimitedDenmark RoadCowesIsle of Wight PO31 7TBUnited Kingdom

STRAINSTALL U.K. LIMITED

2506 AMPLIFIER

Reference Manual

Doc.ref. #11457 Issue 4 Page 3

Health & Safety

All relevant health and safety standards shall apply to anyone involved in the maintenance of theequipment described. See also Section 15.

The Health and Safety at Work Act 1974 requires that all personnel involved in the use, installation,service or repair of such equipment shall be aware of any potential hazards and the precautions indicated.Such personnel must be qualified and competent for the tasks to be undertaken.

Full details of the Act may be obtained from the UK Health and Safety Executive (www.hse.gov.uk).

Contact address

This Manual is intended to meet the requirements of responsible personnel engaged in installation,supervision and usage of the equipment. For further information or assistance, please contact theCommercial Department at:

Strainstall U.K. LimitedDenmark RoadCowesIsle of Wight, PO31 7TBUnited Kingdom

Telephone (international) +44 1983 203600Telephone (inland) 01983 203600Facsimile (international) +44 1983 291335Facsimile (inland) 01983 291335E-mail [email protected]

Liability for Equipment Commissioned by Strainstall

The Company's liability, under the Company's standard conditions of guarantee, will extend to the repairor replacement (at its option) of any item of the Company's supply that fails due to faulty materials orworkmanship. This will be subject to an investigation at the Customer's site when necessary, providingsuch faults are reported to the Company within twelve calendar months from the date of commissioning.

Liability for Equipment Commissioned by Others

The Company's liability under the Company's standard conditions of guarantee, will extend to the repairor replacement (at its option) of any item of the Company's supply which fails due to faulty materials orworkmanship, on return of the equipment to the Company's address, as shown above.

Acceptance of liability will be subject to investigation on return of the equipment, providing such faultsare reported to the Company within twelve calendar months from the date of despatch. If the customerrequires repairs to be carried out on site, then the Customer will be liable for all associated costs.

In all cases, the Company's liability will exclude any modifications or repairs carried out by, or damagecaused by, the Customer or any third party. The Company’s liability does not extend to consequential losses,howsoever caused.


2506 AMPLIFIER

Reference Manual


CONTENTS1. GENERAL........................................................................................................................................................5

2. INSTALLATION.............................................................................................................................................6

3. CHOOSING THE BARRIER.........................................................................................................................6

3.1 APPLICATIONS WITH LOCAL TEST/CAL..........................................................................................................73.2 APPLICATIONS WITH REMOTE TEST/CAL .......................................................................................................7

4. POWER SUPPLY............................................................................................................................................8

5. EARTHING THE BARRIERS.......................................................................................................................8

CONNECTING UP ...................................................................................................................................................9

6.1 CONNECTIONS IN THE HAZARDOUS AREA....................................................................................................106.2 CONNECTIONS TO THE SAFE AREA...............................................................................................................10

7. INTERCONNECTING CABLES.................................................................................................................11

8. ZERO OUTPUT CURRENT........................................................................................................................11

9. INPUT ZERO ADJUSTMENT ....................................................................................................................12

10. SPAN ADJUSTMENT...................................................................................................................................12

11. INTERNAL CALIBRATION CHECK .......................................................................................................12

12. EXTERNAL CAL CHECK ..........................................................................................................................13

13. INTRINSIC SAFETY....................................................................................................................................13

14. CERTIFICATION.........................................................................................................................................13

15. ATEX INSTALLATION NOTES.................................................................................................................14

16. ELECTROMAGNETIC COMPATIBILITY..............................................................................................14

Figure 1 - 2506 amplifier .............................................................................................................5Figure 2 - Example of use with Load Cell (2506A) ...................................................................9

Figure 3 - Example of use with Strain Gauge (2506B) .............................................................9

Figure 4 - Example of use with Half-Bridge Strain Gauge and Local Indicator ...................9

Figure 5 - PCB............................................................................................................................11

DRAWINGS (for information only)


2506 AMPLIFIER

Reference Manual


1. GeneralThe 2506 amplifiers are available in two versions, namely the 2506A for full-bridge straingaugeinputs from sensors such as load cells and pressure transducers, and the 2506B for quarter orhalf-bridge straingauge elements as may be used in structural measurements.

They are normally used in conjunction with a double-channel Zener safety barrier on a 24 Voltsupply. Some compatible combinations are shown below and are documented in BASEEFAsystem certificates, see sections 3 and 14.

They deliver a 4-20mA output (as a source) and are therefore compatible with all conventionalprocess control systems. The output load resistance may be any value up to 300Ω - the inputterminals of a process control system will normally provide 250Ω (1-5V), while an analogue ordigital meter will normally drop between 1 and 3V at 20mA.

The amplifier includes a regulated 8V supply for the bridge, at the maximum available currentwhich is limited by the output resistance of the selected Zener barrier or isolation interface.Minimum values of bridge resistance are shown in section 3 below.

Figure 1 - 2506 amplifier

CAL button

GAIN (RV2)fine adjust

ZERO (RV1)fine adjust

GAIN (S1,S2)coarse adjust

ZERO (S3,S4)coarse adjust


2506 AMPLIFIER

Reference Manual


2. InstallationThe amplifier is built into a conventional enclosure for mounting on a standard symmetricalDIN-rail (TS35 x 7.5 or TS35 x 15). Units will normally be installed in an outer enclosure, bothfor environmental protection and the completion of EMC screening - suitable enclosures ineither metallised polycarbonate or stainless steel are available from Strainstall.

The amplifier should normally be located in the hazardous area near the transducer, so that theintegral transducer cable makes connection to the amplifier terminals without intermediatejunctions.

The amplifier must be installed and operated in an ambient temperature between -20ºC and+60ºC. Further advice on installation requirements is given in section 15 below.

3. Choosing the barrierThe optimum Zener barrier interface will depend on the supply voltage, the lowest value ofresistance of the connected transducer or strain gauge and the gas group of the hazardousatmosphere. The following table shows the majority of the practical combinations:

Supply Voltage Supply Barrier Min Bridge res.2506A

Min Gauge res.2506B

Gas Group

24 - 25 28V300R 500 ohms 350 ohms IIC

24 - 25 28V240R 350 240 IIC

24 - 25 28V164R 175 120 IIB

12 - 13 15V60R 700 500 IIC

12 - 13 15V50R 500 350 IIB

(20 - 25 Isolator 350 240 IIC)

With each barrier example above, a diode return barrier channel will also be needed. In mostcases the supply barrier channel and the diode return may be found packaged together in onedouble-channel unit.


2506 AMPLIFIER

Reference Manual


3.1 Applications with Local Test/CalFor the majority of applications, the 28V240R or 28V234R rating with 28V diode return is thebest choice, examples of typical manufacturer's models are as follows:

RTK S985POS

P&F Z787.H

MTL 787SP+ or 7187SP+

Elcon µZ631+

See system drawing and Section 6 for typical connection arrangements.

Where isolation interfaces are mandatory, then the Pepperl & Fuchs type KFD2-SD-Exl.17together with KFD2-CR-Exl.30-300 may be used.

3.2 Applications with Remote Test/CalWhen the optional Test/Cal facility is to be used remotely in the safe area, an additional 28Vdiode return barrier channel is required. The three barrier channels required may be provided bya variety of single and double channel models available. For example, a single resistive barriermight be combined with a double-channel diode return. Some examples are listed below:

RTK S985POS with S961POS or S967POS with S963POS

P&F Z787.H with half Z786 or Z728.H with Z786

MTL 787SP+ with half 786+ or Z728P+ with 786+

Elcon µZ631+ with half µZ631+ or 1631-3D-P alone

The arrangements include channels in dotted outline in Section 6.

Where isolation interfaces are used, then the Test/Cal facility needs the addition of the optionalintrinsically safe relay interfaces shown in system drawing SYS5570-11-3.


2506 AMPLIFIER

Reference Manual


4. Power SupplyWhere the installation forms part of a larger plant control and instrumentation scheme, theamplifier will usually be powered by the existing bulk +24V DC supply. In stand-aloneapplications, a 12V DC supply is a permitted alternative, with some restriction on bridgeresistance range.

CAUTIONPOWER MUST NOT BE APPLIED DIRECTLY TO THE UNIT WITHOUT THE USE OF A ZENER

BARRIER OR THE CORRECT ISOLATOR.

If bench testing the amplifier without a barrier or isolator, then a series resistor of minimumvalue 180Ω (0.5W) must be included in the supply line, or damage will result.

5. Earthing the barriersFundamental to the safe operation of Zener barriers is the provision of a secure earthconnection. Some users express great concern about earthing, and have been led to believe thatit can be difficult to carry out. In fact, the opposite is usually the case - satisfactory earthing isnormally a straightforward matter.

In many installations, the 2506 amplifier system will be an addition to a plant where a barriercubicle with earthing provision already exists. However, if a new connection to earth is to bemade, a 4sq.mm. green/yellow wire may be run to the earth bar or stud in a local switch-room.Otherwise, use a nearby sound earthing point, for example on the structural steel of the buildingwhose potential can be relied upon to be similar to the earth potential in the hazardous area.

The barrier bus-bar should have its own dedicated earth conductor - do not allow it to be usedfor earthing any other electrical equipment.

Practical advice about the earthing of intrinsically safe installations can be found in BritishStandard EN60079-14 – Electrical Installations in Hazardous Areas.


2506 AMPLIFIER

Reference Manual


6. Connecting up

Figure 2 - Example of use with Load Cell (2506A)

Figure 3 - Example of use with Strain Gauge (2506B)

Figure 4 - Example of use with Half-Bridge Strain Gauge and Local Indicator

2506AAMPLIFIER

Load cell

Zener barrier

Zener barrier

Load250R

Zener barrier24V DC

0V

CALswitch

Optional remote CALswitch connection

P1

P2

S2 S1

9

8

11

7

324

1

SAFE AREA

HAZARDOUS AREA

2506BAMPLIFIER

Strain gauge(¼-bridge

shown)

Zener barrier

Zener barrier

Load250R

Zener barrier24V DC

0V

CALswitch

Optional remote CALswitch connection

P1

DUMMY

S1

9

8

7 (350 ohm)

324

1

(12 if 120 ohm)

SAFE AREA

HAZARDOUS AREA

2506BAMPLIFIER

Strain gauge(½-bridge)

P1

S1

9

8

11P2

24V DC

0V

32

4

SAFE AREA

HAZARDOUS AREA

Zener barrier

54-20mA loop

poweredIS display

(300R max)

1

CALswitch


2506 AMPLIFIER

Reference Manual


6.1 Connections in the Hazardous Area2506A connections for a full-bridge load cell or other transducer:

Supply positive (P1) terminal 9

negative (P2) terminal 11

Signal positive (S2) terminal 7

negative (S1) terminal 8

2506B connections for structural strain gauges:

Supply positive (P1) terminal 9

negative (P2) terminal 11

Signal (S1) terminal 8

dummy (D350) terminal 7

(D120) terminal 12

Half-bridge uses Pl, S1, P2. Quarter-bridge uses Pl, S1, D

6.2 Connections to the Safe AreaTerminal 3 connects through the supply barrier channel to the 24V(12V) supply.

Terminal 4 connects through the diode return barrier for the 4-20mA output.

Terminal 2 connects to the barrier earth return terminal (if fitted) or to the barrier earth busbar.The cable screen is only connected to the barrier screen terminal (it fitted) or direct to the earthbusbar.

Terminals 10 and 6 on the amplifier are provided for the purpose of making a throughconnection for cable screen continuity, free of the intrinsically safe circuit. Cable screens shouldnot be bonded to the outer enclosure, although separate cable armouring may be locally bondedif so required.

Note that, as barrier terminal numbering varies between manufacturers, care will be neededwhen connecting. In case of any doubt, contact Strainstall. The correct connections for isolatorsare given in the installation drawing SYS 5570-11-3.

In the case of installations wholly within the hazardous area (e.g. where an intrinsically safedisplay is used) only one isolator KFD2-SD-Exl.17 will be required, on the DC supply lines.


2506 AMPLIFIER

Reference Manual


7. Interconnecting cablesTo ensure compliance with the requirements for electromagnetic compatibility, it isrecommended that screened cables be employed on both sides of the amplifier.

Limiting reactance (capacitance and inductance) figures for the cables - the cable parameters -are listed on the system drawings, see section 14 below.

In general, none of these figures is at all restrictive in normal instrumentation cables ofmoderate length. However, if the hazard involves Group IIC risks it may be necessary to usecables of conductor size no larger than 0.5mm², while in Group IIB, cable sizes of up to 1.5mm²will be perfectly satisfactory. If in doubt, the cable characteristics must be checked against thesystem drawings before installation.

Large multi-core or multi-pair cables carrying several amplifier circuits are acceptable, but notethat it is not permitted to share a single common (earthed 0V) line between amplifiers - everyamplifier must have its own return conductor.

8. Zero Output CurrentThe output current at zero input signal is factory set to 4mA on the 2506A and 12mA on the2506B, the latter to allow for bi-directional strain measurements. To change this setting,proceed as follows:

1. Withdraw the amplifier from its case by first removing the knob from the pushbuttonswitch, then easing apart the sides of the case at the top while pulling out by the terminalblocks. It may also be necessary to depress the spindle of the pushbutton switch to clear thecase.

2. Locate the test-points TP1 and TP2, and connect a digital multimeter, 2V DC range. Withthe amplifier fully connected up with a transducer (and using a supply resistor if the barrieris not present – see section 4) adjust the zero controls (section 9 below) so that the voltagebetween TP1 and TP2 is zero.

3. Monitor the current between terminal 4 and the load (or 0V) using the 20mA DC range.Adjust RV3 on the circuit board to obtain the required output current. Reassemble theamplifier into its case.

Figure 5 - PCB

Test Points

RV3


2506 AMPLIFIER

Reference Manual


9. Input Zero AdjustmentZero adjustment of the input signal is carried out by use of the top adjuster (Fig.1) inconjunction with the switches S3 and S4 alongside. On the 2506A the range of adjustment isgreatest in the direction needed to offset the positive tare load signals that are a feature of manyload cell applications.

If a particularly large zero offset cannot be reached by the zero controls, then use an externalshunt resistor, e.g. across terminals 8-9 or 8-11 according to the polarity required.

On the 2506A, the zero control will null offsets from –0.05mV/V to +0.40mV/V based on a350Ω bridge, while on the 2506B, the nulling range is from -1000µe to +2000µe (irrespectiveof the strain-gauge resistance).

10. Span AdjustmentAdjustment of the span sensitivity or gain of the amplifier is by the top adjuster (Fig.1) inconjunction with the switches S1 and S2 alongside. Clockwise rotation increases the sensitivity,while the switches S1, S2, S1+S2, provide four ranges of adjustment. The greatest sensitivity isprovided with both switches ON.

If calibrating without a known load on the transducer, the calibration check provision can beused to obtain a close setting to the desired sensitivity. See section 11 below.

On the 2506A, the full scale sensitivity can be varied from 0.23mV/V to 3.5mV/V, while on the2506B, the range is from 200µe to 3000µe (±100µe to ±1500µe for bipolar applications) basedon a single active arm at gauge factor K=2.

11. Internal Calibration CheckThe amplifier includes an in-built 350K one-arm shunt calibration resistor. Operation of thepushbutton CAL switch applies this resistor across the S1 and P2 bridge terminals, resulting inan offset of 0.25mV/V or 0.50mV/V on a 350 ohm or 700 ohm symmetrical bridge transducerrespectively.

In normal operation, the CAL switch is used periodically as a check on the response of thesystem, without having to perform the ultimate check of applying a known load to thetransducer which, especially on large load cells, may be difficult to arrange.

For initial setting-up purposes, this offset may be calculated as a proportion of the known full-scale sensitivity of the transducer. For example, on a 700 Ohm 30 tonne load cell having anoutput of 1.50mV/V at full load, the offset would be equivalent to a 10 tonne change in load.

If the transducer is not symmetrical (for example it may contain scaling or compensatingresistors that affect its symmetry or its input/output resistance), then the 350K CAL resistor mayinstead be compared to the value of a calibration resistor which may be stated on the load cellcalibration sheet. For example, if a calibration resistor of 120K is said to reproduce an 87% fullscale reading, then the CAL switch would give an approximately 30% scale signal, by inverseproportion.


2506 AMPLIFIER

Reference Manual


12. External Cal CheckThe amplifier also contains a solid-state relay to switch in the CAL resistors remotely thatperforms the same function as the pushbutton CAL switch. Terminal 1 on the amplifier is closedto 0V (e.g. terminal 5) to energise the relay.

If required, a switch may be mounted within the same hazardous area to make a calibrationcheck, such a switch may be any simple type chosen for its application suitability. In the contextof intrinsic safety, it does not need to be a certified switch.

Alternatively, if it is required to be able to perform a CAL check in the remote safe area, then anadditional conductor from terminal 1 may be routed back to the barrier cubicle within the samecable as the power and signal. This additional core would be connected to an additional Zenerbarrier channel of the diode return type and the safe area CAL switch would connect to the safearea terminals of the additional barrier. In the case of installations using isolation interfaces, theextra CAL line is handled by the addition of one of three types of intrinsically safe relayinterfaces listed in the approved system drawing, see section 14 below.

13. Intrinsic SafetyThe intrinsic safety of the 2506 amplifiers is characterised by the following parameters:

Ui = 30V Ii = 300mA Pi = 1.2W

Ci = 0 Li = 0.1mH L/R = 19µH/Ω

The unit may be connected to any combination of Zener safety barriers whose total outputparameters do not exceed any of the Ui, Ii or Pi parameters stated above. If used with isolationinterfaces, only those specified in the relevant system drawing may be used, the use of otherisolators would be the subject of a new system certification.

14. CertificationThe amplifier is certified by EECS (BASEEFA) to BS EN50014 and BS EN50020 as follows:

Certificate No. BAS01ATEX1025X

Category EEx ia IIC T4 -20ºC ≤ Ta ≤ 60ºC II 1 G

The following intrinsically safe system certificates are also issued:

Certificate No. Ex01E2031 - IIC system with Zener barriers.

Strainstall drawing No. SYS5570-11-1 applies.

Certificate No. Ex01E2032 - IIB system with Zener barriers.


Certificate No. Ex01E2033 - IIC system with isolation interfaces.



2506 AMPLIFIER

Reference Manual


15. ATEX Installation NotesIn accordance with ATEX Directive 94/9/EC, Essential Health & Safety Requirements (AnnexII), attention is drawn to the following:

• The user must verify that the product Category and Group as stated on the product label andin the installation instructions are appropriate for the hazardous area circuit to which it isconnected.

• This product is intended for installation by competent trained personnel into a larger pieceof equipment or system.

• This product must be fixed into a suitable enclosure where it is free from attack by existingor foreseeable aggressive substances and where it is protected against excessiveaccumulation of dust.

• This product should be installed and maintained in accordance with the standards applicablein the country or state of use, in addition to any local or site requirements that may apply.

• Apart from the terminals provided for the purpose, the user is not permitted access to thecircuitry of this product.

• This product must be mounted using the standard mounting arrangements provided, and notbe subject to mechanical stresses.

• This product must be installed in an ambient temperature not exceeding that stated in theinstallation instructions, and not be subjected to thermal stresses.

• The user is required to suppress high-energy transients, such as those caused by lightningstrikes. Non-resistive loads and contact arcing must be suppressed at source.

• Anti-static precautions and engineering best practice must always be observed.

• No attempt should be made to repair this product other than by the manufacturer or hisauthorised repair agent. It should be replaced by an identical or equivalent certified product.

• This product has been designed to avoid physical injury or harm, high surface temperaturesor radiation, or any other non-electrical dangers that can be foreseen.

16. Electromagnetic CompatibilityIn accordance with the EMC Directive this product has been tested for the industrialEnvironment (BS EN50081-2 and BS EN50082-2). Operation in any other environment is notguaranteed and is at the risk of the User.

The performance of this product will meet the requirements of the relevant performance criteriaas determined by the particular tests listed in the EMC standards. The product may be affectedtemporarily by the application of some electromagnetic disturbances, but will return topublished specification thereafter.

Doc.ref. #11457 Issue 4 Appx.

Drawings(for information only)

SYS 5570-11-1SYS 5570-11-2

SYS 5570-11-3 (Iss.2)

A

B

C

D

E

F

A

B

C

D

E

F

21 3 4 5 6 7 8

1 32 76 8

THIRD ANGLE PROJECTIONDRAWN TO BS308

DIMENSIONS IN MILLIMETRESDRG

NO

.

DRAWN CHECKED APP.D DATE SCALE DRG NO.

TITLE

NO. ALTERATION DESCRIPTION

MATERIAL

FINISHC STRAINSTALL UK LTD

AND MUST NOT BE SHOWN TO THIRD PARTIES. THIS SHEET AND ALL COPIES MUST BE RETURNED ON DEMAND.THE INFORMATION ON THIS SHEET MAY BE USED ONLY FOR THE PURPOSE FOR WHICH IT IS SUPPLIED BY THE COMPANY

CHKD APPD DATE

ANGULAR DIMENSIONSTWO PLACE DECIMALSONE PLACE DECIMALSUNITS

TOLERANCES UNLESSOTHERWISE SPECIFIED

± 0.15± 0.07± 1/2°

± 0.5

StrainstallDenmark Road, Cowes, Isle of Wight, PO31 7TB

25/3/02 N/A

SYS

5570

-11-

3

2 MODIFIED TO M2396

SYS 5570-11-3

GROUP C HAZARDOUS AREA - ZONE 0, 1 OR 2 NON HAZARDOUS (SAFE) AREA

SEE NOTE 2

SEE NOTE 3

SEE NOTE 4

SEE NOTE 6SEE NOTE 5

SEE NOTE 10L/RLmHCµFGROUP

0.421.574.18

30125250

CBA

TABLE 1.MAXIMUM CABLE PARAMETERS

B 2061.13A 3.01 412

TABLE 2.GROUP

CCµF LmH

0.38L/R412.01

16.475.0

AMPLIFIER TYPE 2506 SYSTEM DRAWING

(ISOLATION INTERFACES)C

NOTES. 1.NON-HAZARDOUS AREA EQUIPMENT IS UNSPECIFIED EXCEPT THAT IT SHALL NOT GENERATE NOR CONTAIN A SOURCE OF EMF IN EXCESS OF 250V AC OR DC. 2.ONE PEPPERL AND FUCHS TYPE KFD2-CR-Exl.30-300 ISOLATOR, CERTIFICATE NO.Ex89C2003 OR BAS 00ATEX7164. CONNECT ONLY AS SHOWN 3.ONE PEPPERL AND FUCHS TYPE KFD2-SD-Exl.17 ISOLATOR, CERTIFICATE NO.Ex97D2072 OR BAS 00ATEX7216. CONNECT ONLY AS SHOWN 4.OPTIONAL INTRINSICALLY SAFE RELAY INTERFACE WHICH MAY BE EITHER PEPPERL AND FUCHS TYPE ZG40/Ex (CERT NO.Ex86B2162), RTK TYPE RLSH1A (CERT. NO. Ex96D2019) OR MTL TYPE MTL4215 OR MTL4216(CERT. NO. Ex94C2015). WHOSE TERMINALS MAY BE CONNECTED ONLY AS IN TABLE 3. 5.ONE AMPLIFIER TYPE 2506A OR 2506B TO CERTIFICATE NO. BAS01ATEX1025X. 6.RESISTIVE FIELD APPARATUS WHOSE TERMINAL CHARACTERISTICS CONFORM TO THOSE OF SIMPLE APPARATUS AS DESCRIBED IN PARAGRAPH 5.4 OF EN50020:1995. 7.INTERCONNECTING CABLE WHOSE REACTIVE PARAMETERS DO NOT EXCEED THE VALUES GIVEN IN TABLE 1. 8.INTERCONNECTING CABLE WHOSE REACTIVE PARAMETERS DO NOT EXCEED THE VALUES GIVEN IN TABLE 2. 9.IF THE FIELD CIRCUIT IS ISOLATED FROM EARTH, THE SYSTEM MAY OPTIONALLY BE EARTHED AS SHOWN IF IT IS REQUIRED TO AVOID THE ELECTROSTATIC CHARGING OF THE FIELD CABLES10.OPTIONAL TEST SWITCH WHOSE TERMINALS CONFORM TO THOSE OF SIMPLE APPARATUS AS DESCRIBED IN PARAGRAPH 5.4 OF EN50020:1995.11.IF SCREENED CABLES ARE USED, THEN THEY MUST BE EARTHED AT ONE POINT ONLY AND BE ABLE TO WITHSTAND AN INSULATION TEST OF 500V FOR 1 MINUTE TO THE INTRINSICALLY SAFE CIRCUIT.12.THE INSTALLATION SHOULD BE CARRIED OUT IN ACCORDANCE WITH THE RELEVANT INSTALLATION REQUIREMENTS, e.g. BS5345, BS EN60079, ETC.13.THE SYSTEM SHOULD BE MARKED EITHER ON THE PRINCIPAL ITEM OF EQUIPMENT OR AT THE HAZARDOUS AREA INTERFACE WITH A DURABLE LABEL SHOWING "BASEEFA SYSTEM CERTIFICATE NO. Ex01E2033".

SEE NOTE 8

SEE NOTE 7

2.068.50

0.353

2

3

8

7

11

12

1

2

7

8

4-20mA

+ 24V

OV

SEE NOTE 9

SEE NOTE 1

H S

11

9

8

7(12) 1

3

4

2

1 5

TABLE 3

MTL

RELAYRTKP & F

1-3 or 4-61-3 or 2-4

11-14TERMINALS" H"

8-9 or 10-115-6

+ and -TERMINALS"S"

or

or

-+

+-

+

4-20mA

INTRINSICALLY SAFE AMPLIFIER Type 2506 Reference Manual IS Amplifiers/2506... · STRAINSTALL U.K. LTD. INTRINSICALLY SAFE AMPLIFIER Type 2506 Reference Manual Strainstall Document

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