BEKA BA307E Intrinsically Safe 4 20ma Loop Powered Indicators Installation Guide

BEKA BA307E Intrinsically Safe 4 20ma Loop Powered Indicators

Product Information

BA3xx Series Intrinsically Safe 4/20mA Loop Powered Indicators

The BA3xx Series Intrinsically Safe 4/20mA Loop Powered Indicators are a fourth-generation range of instruments designed for use in hazardous areas. These indicators have international intrinsic safety certifications, allowing their installation in gas and dust hazardous areas worldwide.

Intrinsic Safety Certifications

• IECEx certification: All models have an IECEx Certificate of Conformity issued by Intertek Testing & Certification Ltd. IECEx certificates allow worldwide installation, conforming to EN 60079:14 Electrical installations design, selection, and erection.
• ATEX & UKEX certification: The BA3xx series indicators also have ATEX and UKEX certifications, enabling their use in European hazardous areas.
• US and Canadian certification: The BA307E, BA308E, BA327E, BA328E, BA304G, and BA324G models have FM, ETL, and cETL certifications for use in North America.

Description

• 4/20mA Loop Powered: The indicators are loop powered by the 4/20mA current they are measuring and do not require an additional power supply.
• Backlighting: The indicators have optional display backlighting, which can be loop-powered or separately powered.
• Alarms: Optional alarms are available for the indicators.
• Special Functions: The indicators have special functions such as a square root extractor, linearizer, and tare.
• Rugged Panel Indicator Application: The BA307E-SS, BA327E-SS, BA304G-SS-PM, and BA324G-SS-PM models are rugged stainless steel panel mounting indicators suitable for various panel enclosures.

Product Usage Instructions

1. 4/20mA Loop Design

The BA3xx series indicators are loop powered by the 4/20mA current they are measuring. Connect the indicator to the loop circuit according to the electrical installation design, ensuring compliance with local codes and regulations.

2. Remote Indication

The indicators can be used for remote indication by connecting them to the appropriate 4/20mA loop circuit in the desired location.

3. Display Backlight

The indicators have optional display backlighting. To power the backlight using the loop circuit, follow the loop powering instructions provided in the user manual. Alternatively, if separate powering is desired, follow the separately powering instructions.

4. Optional Alarms

If required, optional alarms can be installed on the indicators. Refer to the user manual for detailed instructions on installing and configuring alarms.

5. Special Functions

The indicators have special functions such as a square root extractor, linearizer, and tare. Consult the user manual for instructions on utilizing these functions.

6. Rugged Panel Indicator Application

For installation in an Ex e or Ex p panel enclosure, refer to the specific instructions provided in the user manual for the BA307E-SS, BA327E-SS, BA304G- SS-PM, and BA324G-SS-PM models.

Note: For installation in hazardous areas in the USA and Canada, follow the instructions provided in the user manual for the FM, ETL, and cETL certified models.

INTRODUCTION

The first BA3xx series intrinsically safe loop powered 4/20mA indicator was introduced in 1984, since then the range has been continuously developed through the B, C and D models. This edition of Application Guide AG300 describes the use of the fourth generation intrinsically safe E & G instruments including the rugged stainless steel panel mounting models introduced in 2014 and extended in 2018.
For applications in Zone 2 without the need for an intrinsically safe interface such as a Zener barrier or galvanic isolator, the Ex eb certified BA304SG and the BA324SG field mounting indicators are already available. Panel mounting BA307SE and BA327SE indicators having Ex ec certification will be available in February 2023.
The BA5xx series duplicates the complete range of field and panel mounting models for safe area applications.

DESCRIPTION

The BA3xx series indicators are loop powered by the 4/20mA current they are measuring and do not require an additional power supply. All the models can be calibrated to display the 4/20mA input current in engineering units, they may be used in new installations and are electronically backwards compatible allowing them to replace earlier B, C and D suffix models.
Fig 1 shows a simplified block diagram of a BA3xx series indicator. The 4/20mA input current flows through resistor R1 and forward biased diode D1. The voltage developed across D1, which is relatively constant, is multiplied and used to power the analogue to digital converter and the liquid crystal display. The voltage developed across R1, which is proportional to the 4/20mA input current, provides the input signal for the analogue to digital converter. This technique allows all models to drop less than 1.2V in the 4/20mA loop, and enables the two input terminals to comply with the requirements for simple apparatus.

Fig 1 Simplified block diagram of a BA3xx intrinsically safe indicator.
The features of all the intrinsically safe BA3xx models are summarised in Tables 1 and 2. Detailed specifications for each model are contained in individual datasheets available from BEKA associates sales department or they may be downloaded from the BEKA website at www.beka.co.uk/datasheets.html.

INTRINSIC SAFETY CERTIFICATIONS

The BA3xx series indicators have international intrinsic safety certifications allowing them to be installed in gas and dust hazardous areas worldwide.

IECEx certification
All models have an IECEx Certificate of Conformity issued by Intertek Testing & Certification Ltd. IECEx certificates allow worldwide installation, either directly or as a means to obtain local approval. This guide describes installations which conform to EN 60079:14 Electrical installations design, selection and erection. When designing systems the local Code of Practice should be consulted.

ATEX and UKCA certification
Notified Body Intertek Italia S.p.A have issued the BA3xxE & BA3xxG series indicators and the BA326C with EU-Type Examination Certificates which have been used to claim compliance with the European ATEX Directive 2014/34/EU.
UK Approved Body Intertek Testing & Certification Ltd have issued the BA3xxE & BA3xxG series indicators and the BA326C with UKCA Certificates of Conformity which have been used to claim compliance with UK statutory requirements for Equipment and Protective Systems Intended for Use in Explosive Atmospheres Regulations UK SI 2016:1107 (as amended).
All models carry both the EU Community and UKCA Marks. Subject to local codes of practice, they may be installed in any of the EEA member countries and in the UK. When designing systems for installation outside the UK, the local Code of Practice should be consulted.

US and Canadian certification
All models except the BA304G-SS-PM, BA324G-SS-PM and the BA326C have certification allowing installation in the USA and Canada which have been issued by two Nationally Recognised Testing Laboratories NRTLs, FM and ETL. For the USA both the traditional NEC500 Class and Division classification, which is acceptable for installation on most North American sites, and the more recent NEC505 Zone classification are included. US NEC505 intrinsic safe equipment is coded AEx and the approval is similar to international IECEx and European ATEX certifications.
Canadian certification also includes both Division and Zone classifications. The Canadian Electrical Code mandates that new installations use Zones, but Class and Divisions are still frequently employed.

Shown with optional backlight

|

|

|

|

Enclosure material & size| Field                      Field

GRP                Stainless steel 316

122 x 120mm          122 x 120mm

| Field GRP

122 x 120mm

| Field

Stainless steel 316

122 x 120mm

Protection| IP66
Number of digits| 4| 4| 5

and 31 segment bargraph

| 5

and 31 segment bargraph

Height of digits| 34mm| 34mm| 29mm| 29mm
Certification International & Europe

IECEx  gas

|

Ex ia IIC T5 Ga -40°C [ Ta [ +70°C

dust| Ex ia IIIC T80°C Da IP66 -40°C [ Ta [ +70°C
ATEX & UKCA gas| II 1G, Ex ia IIC T5 Ga -40°C [ Ta [ +70°C
dust| II 1D, Ex ia IIIC T80°C Da IP66 -40°C [ Ta [ +70°C
Additional certifications| China  CCC

India    CCOE/PESO

Certification USA & Canada

| Class I, Div 1, Gp A, B, C & D T5 Class I, Zone 0, AEx ia IIC T5 Ga (USA only)

-40ºC [ Ta [ 70ºC

Class II, Div 1, Gp E, F & G. Class III, Div 1 Zone 20 AEx ia IIIC T80ºC Da (USA only)

-40ºC [ Ta [ 60ºC

Ex ia T5 Ga -40ºC [ Ta 70ºC Ex ia IIIC Da -40ºC [ Ta [ 60ºC

Additional certification features|

None

Options| Optional items must be specified when indicator is ordered

Certification

IECEx, ATEX & UKCA dust US and Canadian

Backlight Alarms

|

Standard Standard Available Available

|

Standard Standard Available Available

|

Standard Standard Available Available

|

Standard Standard Available Available

|

|

|

|

Panel PPO (Noryl) 96 x 48mm| Panel PPO (Noryl) 96 x 48mm| Panel PPO (Noryl) 144 x 72mm| Panel PPO (Noryl) 144 x 72mm| Panel PPO (Noryl) 144 x 48mm
Front IP66 rear IP20| Front IP65 rear IP20
4| 5

and 31 segment bargraph

| 4| 5

and 31 segment bargraph

| Analogue 95mm long

100 segments

Digital     4½ digits

15mm| 11mm| 34mm| 29mm| 5.5mm

Ex ia IIC T5 Ga -40°C [ Ta [ +70°C

| Ex ia IIC T5 Ga

-40°C [ Ta [ +60°C

Ex ia IIIC T80°C Da IP20 -40°C [ Ta [ +70°C| –
II 1G, Ex ia IIC T5 Ga -40°C [ Ta [ +70°C| II 1G, Ex ia IIC T5 Ga

-40°C [ Ta [ +60°C

 II 1D, Ex ia IIIC T80°C Da IP20 -40°C [ Ta [ +70°C|
China  CCC

India    CCOE/PESO

|

–

Class I Division 1 Groups A, B, C & D T5 Class I Zone 0 AEx ia IIC T5

-40ºC [ Ta [ +70ºC

|

–

None

Standard Standard Available Available

|

Standard Standard Available Available

|

Standard Standard Available Available

|

Standard Standard Available Available

| See Section 10 N/A

N/A

Only separately powered

Available

Shown with optional backlight

|

|

|

|

Enclosure material & size| Panel Stainless steel 316

105 x 60mm

| Panel Stainless steel 316

122 x 120mm

Protection| Front impact resistant & IP66 rear IP20
Number of digits| 4| 5

and 31 segment bargraph

| 4| 5

and 31 segment bargraph

Height of digits| 15mm| 11mm| 34mm| 29mm
Certification International & Europe

IECEx  gas

|

Ex ia IIC T5 Ga -40°C [ Ta [ +70°C

dust| Ex ia IIIC T80°C Da IP66 -40°C [ Ta [ +70°C
ATEX & UKCA  gas| II 1G, Ex ia IIC T5 Ga -40°C [ Ta [ +70°C
dust| II 1D, Ex ia IIIC T80°C Da IP66 -40°C [ Ta [ +70°C
Additional certification features| Certification permits installation in Ex e, Ex p or Ex t panel enclosure without invalidating the panel enclosure’s certification.

Certification USA & Canada

| Class I Division 1 Groups A, B, C & D T5 Class II Division 1 Groups E, F & G T5 Class III T5

Class I Zone 0 AEx ia IIC T5

-40ºC [ Ta [ +70ºC

|

–

Additional certification features| Certification permits installation in AEx e, AEx p or AEx t panel enclosure without invalidating enclosure’s certification.|

None

Options| Optional items must be specified when indicator is ordered

Certification

IECEx, ATEX & UKCA dust US and Canadian

Backlight Alarms

|

Standard Standard Available Available

|

Standard Standard Available Available

|

Standard N/A Available Available

|

Standard N/A Available Available

DESCRIPTION OF IECEX, ATEX & UKCA GAS CERTIFICATION.

All of the BA3xx series indicators and accessories have IECEx, ATEX and UKCA certification. This section describes certification for installation in a gas hazardous area, section 5 describes dust certification.

Certification label
All BA3xx series indicators are fitted with an external label showing the IECEx, ATEX and UKCA certification information and numbers. The gas certification information on a BA304G certification label is highlighted in Fig 2.

Fig 2 BA304G gas certification label (top left section)

Zones, gas groups and T rating
All of the BA3xx series indicators have the following gas certification code:

IECEx
Ex ia IIC T5 Ga
-40ºC ≤ Ta ≤ 70ºC (Except BA326C)
ATEX & UKCA
Group II Category 1G, Ex ia IIC T5 Ga -40ºC ≤ Ta ≤ 70ºC (Except BA326C)

When connected to a suitable system the indicator may be installed in:

• Zone 0 explosive gas air mixture continuously present.
• Zone 1 explosive gas air mixture likely to occur in normal operation
• Zone 2 explosive gas air mixture not likely to occur, and if it does will only exist for a short time.

Be used with gases in groups:

• Group A propane
• Group B ethylene
• Group C hydrogen

In gases that may safely be used with equipment having a temperature classification of:

• T1 450ºC
• T2 300ºC
• T3 200ºC
• T4 135ºC
• T5 100ºC

At an ambient temperature between
-40ºC and +70ºC (BA326C -40ºC and +60ºC)
This allows the BA3xx series indicators to be installed in all Zones and to be used with most common industrial gases at an ambient temperature between -40ºC and +70ºC. Known exceptions (listed in IEC 60079-20-1) being carbon disulphide and ethyl nitrate which have an ignition temperature of 95ºC.

Note 1: BA304G and BA324G intrinsically safe field mounting indicators in GRP enclosures may be fitted with a label containing aluminium and are therefore subject to the following conditions for safe use indicated by an ‘X’ suffix on the IECEx, ATEX and UKCA certification numbers.

When installed in a Zone 0 potentially explosive atmosphere requiring Equipment Protection Level Ga apparatus, the instrument shall be installed such that even in the event of rare incidents, an ignition source due to impact or friction between the aluminium label and iron/steel is avoided.

These special conditions for safe use of field mounting BA304G and BA324G GRP indicators are not restrictive as it is very unlikely that an indicator would be installed in Zone 0 where a potentially explosive atmosphere is always present. The requirement does not apply when a GRP indicator is installed in Zone 1 or 2.
The requirement does not apply to BA304G-SS, BA324G-SS, BA304G-SS-PL and BA324G-SS-PM indicators which have stainless steel enclosures and labels.

4/20mA input

Sources of energy that do not generate more than 1.5V, 100mA and 25mW are, for intrinsic safety purposes, considered to be simple apparatus (Clause 5.5 of IEC 60079:11). Simple apparatus is easier to incorporate into intrinsically safe systems and requires less documentation than other certified intrinsically safe apparatus.
Although the BA3xx series indicators do not themselves comply with the requirements for simple apparatus, the IECEx, ATEX and UKCA certificates specify that under fault conditions the voltage, current and power output (Uo; Io; Po) from the 4/20mA input terminals will not exceed those specified for simple apparatus. For most applications this allows the output safety parameters of the indicator to be ignored when calculating the intrinsic safety of a loop into which an indicator is inserted.
It is only necessary to establish that the output parameters of the loop are equal to or less than the input parameters of the indicator and that the internal inductance and capacitance of the indicator are acceptable.
The output parameters of the loop which are determined by the intrinsically safe interface powering the loop, be it a Zener barrier, galvanic isolator or associate apparatus should be equal to or less than:

• Uo ≤ 30V dc
• Io ≤ 200mA
• Po ≤ 0.84W

The maximum equivalent capacitance and inductance between the two 4/20mA input terminals 1 and 3 of an indicator are:

• BA3xxE/BA3xxG /BA326C
• Ci = 13nF /5.4nF /20nF
• Li = 0.01mH /0.02mH /0.01mH

To determine the maximum permissible cable parameters of the loop, these figures, plus Ci and Li for any other instruments in the loop, should be subtracted from the specified Co and Lo for the Zener barrier, galvanic isolator or associate apparatus powering the loop.
Apparatus certificates for intrinsically safe interfaces usually specify Co and Lo for IIC gases (hydrogen), the figures for IIB (ethylene) and IIA (propane) gases are considerably larger.
It is unlikely that the additional inductance of the indicator will be restrictive and can usually be ignored, but the additional indicator capacitance will reduce the maximum permissible cable length.

Optional display backlighting
All BA3xx series indicators can be supplied with an optional factory fitted green backlight that has three terminals allowing it to be loop or separately powered. The exception being the backlight for the BA326C combined analogue and digital indicator which can only be separately powered.
When loop powered, the backlight produces background illumination allowing the indicator display to be read at night and in poor lighting conditions. Loop powering does not require an additional power supply, intrinsically safe interface or field wiring, but the maximum voltage drop in the 4/20mA loop caused by the indicator is increased from 1.2 to 5.0V. Backlight brilliance is constant between 6 and 20mA but slightly diminishes below 6mA.
When separately powered, the backlight produces a slightly brighter background illumination which enhances daylight viewing of the indicator display, but an additional intrinsically safe interface and field wiring are required. The maximum voltage drop of the indicator in the 4/20mA loop remains at 1.2V.

Loop powering
To power the display backlight from the 4/20mA loop, backlight terminals 12 & 13 are connected in series with the 4/20mA indicator input terminals as shown in Fig 6.
The IECEx, ATEX and UKCA certificates confirm that terminals 3 & 12 comply with the requirements for simple apparatus when the indicator’s 4/20mA input terminals 1 & 3 are connected in series with the backlight, terminals 12 & 13. The input intrinsic safety parameters of the combined indicator and loop powered backlight are the same as those for the indicator alone. The indicator and loop powered backlight may therefore be connected in series with any certified intrinsically safe loop providing the output parameters of the loop do not exceed:

• Uo ≤ 30V dc
• Io ≤  200mA
• Po ≤ 0.84W

The maximum equivalent capacitance and inductance between input terminals with loop powered backlight are:

• BA3xxE/BA3xxG
• Ci = 13nF /3.3nF
• Li = 0.01mH /0.02mH

To determine the maximum permissible cable parameters of the loop, these figures, plus Ci and Li of any other instrument in the loop, should be subtracted from the specified Co and Lo for the Zener barrier, galvanic isolator or associated apparatus powering the loop.
The loop powered backlight increases the maximum voltage drop of the BA3xx series indicators to 5V.

Separately powering
The backlight is segregated from all other circuits within the indicator and has been certified as a separate intrinsically safe circuit. It is powered via terminals 12 and 14 as shown in Fig 7 which may be connected to any intrinsically safe power supply such as a certified Zener barrier or galvanic isolator having output parameters equal to or less than:

• Uo ≤ 30V dc
• Io ≤  200mA
• Po ≤ 0.84W

The IECEx, ATEX and UKCA certificates specify that the maximum equivalent capacitance and inductance between the backlight terminals is:

• BA3xxE/BA3xxG /BA326C
  • Ci =13nF/3.3nF /30nF
  • Li = 0.01mH /0.01mH /0.01mH

To determine the maximum permissible cable parameters these figures should be subtracted from the specified Co and Lo for the Zener barrier or galvanic isolator powering the backlight.
Optional alarms
All indicators can be supplied with two factory fitted single pole solid state alarm outputs. Each output is galvanically isolated and has been certified as a separate intrinsically safe circuit which, complies with the requirements for simple apparatus.
This allows each alarm output to switch any intrinsically safe circuit with output parameters not exceeding:

• Uo ≤ 30V dc
• Io ≤  200mA
• Po ≤ 0.84W

The IECEx, ATEX and UKCA certificates specify that the maximum equivalent capacitance and inductance between the terminals of each alarm output is:

• BA3xxE/BA3xxG /BA326C
• Ci = 24nF /0 20nF
• Li = 0.01mH/0.01mH/0.01mH

To determine the maximum permissible cable parameters these figures, plus Ci and Li for other apparatus in the circuit, should be subtracted from the specified Co and Lo of the Zener barrier, galvanic isolator or associated apparatus powering the circuit.

DESCRIPTION OF IECEX, ATEX & UKCA DUST CERTIFICATION

All BA3xx intrinsically safe indicators except the BA326C have IECEx, ATEX and UKCA dust certification.

Certification label
All BA3xx series indicators are fitted with an external label showing the IECEx, ATEX and UKCA certification information and numbers. The dust certification information on a BA304G certification label is highlighted in Fig 3.Fig 3 BA304G dust certification label (top left section)

Zones, dust groups and surface temperature

All of the BA3xx series except the BA326C indicators have the following dust code:
Group II Category 1D Ex ia IIIC T80ºC Da
-40ºC ≤ Ta ≤ 70ºC
When connected to a suitable system the indicators may be installed in:

Zone 20
explosive atmosphere in the form of a cloud of combustible dust in air is continuously present, or for long periods or frequently.
Zone 21
explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur occasionally in normal operation.
Zone 22
explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation, but if it does occur, will only persist for a short period.

Be used with dust in subdivisions:

• IIIA combustible flyings
• IIIB non-conductive dust
• IIIC conductive dust. See note

Having a Minimum Ignition Temperature of:

• Dust cloud 120°C
• Dust layer on indicator 155°C up to 5mm thick
• Dust layer on indicator Refer to over 5mm thick.  IEC 60079-14

At an ambient temperature between -40 and +70°C.
Note: BA3xxE series panel mounting indicators have IP20 rear protection and are subject to the following special conditions for safe use indicated by an ‘X’ suffix on the IECEx, ATEX and UKCA certification numbers.
‘When installed in a IIIC conductive dust atmosphere, the indicator shall be mounted such that the instrument terminals have at least IP6X protection.’
These special conditions do not affect installations in IIIA, IIIB dust or gas atmospheres.
IP6X indicates that the rear of the panel mounting indicator should be totally protected from dust, by for example mounting the indicator in a sealed IP6X panel enclosure or cubicle so that conductive dust can not accumulate on the indicator terminals. For 96 x 48mm and rugged indicators, this can be achieved with a BA495 rear cover sealing kit.

DESCRIPTION OF NORTH AMERICAN CERTIFICATION

BEKA loop powered indicators have been certified intrinsically safe for use in the USA and Canada by two Nationally Recognised Testing Laboratories, FM Global and  ETL. Class / Division and Zone approval is included for all models, except the BA326C.
All installations in the USA should comply with the associated BEKA Control Drawing Installation of Intrinsically Safe Systems for Hazardous (Classified) Locations ANSI/ISA RP12.6 and the National Electrical Code ANSI/NFPA70. Any local code of Practice should also be consulted.
Installations in Canada should comply with the associated BEKA Control Drawing, the Canadian Electrical Code C22.1, plus any relevant local code of practice.
FM certification of BA307E, BA308E, BA327E & BA328E
The BA307E, BA308E, BA327E and the BA328E panel mounting indicators have the following FM and cFM intrinsic safety codes:

• Class I/Division 1 /Groups A, B, C & D T5
• Class I/Zone 0 /AEx ia IIC T5
  -40ºC ≤ Ta ≤ +70ºC

When connected to a suitable system these panel mounting indicators may be installed in:

• Division 1
  Explosive gas air mixture likely to occur in normal operation

• Division 2
  Explosive gas air mixture not likely to occur and if it does will only exist for a short time.

Be used with gases in groups:

• Group A Acetylene
• Group B Hydrogen
• Group C Ethylene
• Group D Propane

In gasses that may safely be used with equipment having a temperature classification of:

• T1 450ºC
• T2 300ºC
• T3 200ºC
• T4 135ºC
• T5 100ºC

At an ambient temperature between -40ºC and +70ºC
Note: AEx ia IIC T5 Zone coding allows installation in atmospheres similar to those specified for IECEx and ATEX certification in section 4.
FM & cFM certification of the rugged BA307E-SS & BA327E-SS is described in section 9.1.7

ETL and cETL certification of BA304G & BA324G
The BA304G and the BA324G field mounting indicators have the following ETL and cETL intrinsic safety code:

When connected to a suitable system the BA304G and BA324G field mounting indicators may be installed in:

• Division 1
  Explosive gas air mixture likely to occur in normal operation

• Division 2
  Explosive gas air mixture not likely to occur and if it does will only exist for a short time.

Be used with gases in groups:

• Group A Acetylene
• Group B Hydrogen
• Group C Ethylene
• Group D Propane

In gasses that may safely be used with equipment having a temperature classification of:

• T1 450ºC
• T2 300ºC
• T3 200ºC
• T4 135ºC
• T5 100ºC

At an ambient temperature between -40ºC and +70ºC
Be used in dusts in groups:

• Group E Metal
• Group F Carbonaceous
• Group G Non-carbonaceous

At an ambient temperature between -40ºC and +60ºC

Note: AEx ia IIC T5 Ga and AEx ia IIIC T80ºC Zone codings allow installation in atmospheres similar to those specified for IECEx certification in sections 4 and 5.

HAZARDOUS AREAS APPLICATIONS

BA3xx series IECEx, ATEX and UKCA, US and Canadian certifications specify common indicator safety parameters. The circuits shown in this section may be used with all indicators and with any of the intrinsic safety certifications providing that the installation complies with the local code of practice.
The four rugged stainless steel panel mounting indicators have the same IECEx, ATEX and UKCA gas and dust certification as the other models, although only the BA307E-SS & BA327E-SS have US certification. Whilst they may be used in any of the examples shown in this section, their certification also permits them to be mounted in an aperture in a certified Ex e, Ex p or Ex t panel enclosure without invalidating the panel enclosure’s certification which further extends their applications. The use of these rugged instruments in certified panel enclosures is explained in section 9 of this guide.

4/20mA loop design
A BA3xxG or E series indicator may be connected in series with almost any intrinsically safe 4/20mA current loop and calibrated to display the measured variable or control signal in engineering units. There are four design steps:

1. From tables 1 or 2 select the model with the required display, mounting and accessories.
   4 digit models can display -9999 to 9999
   5 digit models can display -99999 to 99999 with a bargraph

2. 2. The output safety parameters of the 4/20mA loop, which are usually defined by the Zener barrier, galvanic isolator or associated apparatus powering the loop, must be equal to or less than the maximum input safety parameters of the indicator, which are:

   • Uo ≤ 30V dc
   • Io ≤ 200mA
   • Po ≤ 0.84W

3. The equivalent internal capacitance Ci and internal inductance Li of the indicator without a loop powered backlight is:

   • BA3xxE /BA3xxG /BA326C
   • Ci = 13nF /5.4nF /20nF
   • Li = 0.01mH/0.02mH /0.01mH
     When added to the Ci and Li of other instruments in the loop, the totals should not exceed the specified Co and Lo of the Zener barrier, galvanic isolator or associated apparatus powering the loop.

4. The loop must be able to supply the additional 1.2V required to operate the indicator. If the optional backlight is loop powered, the loop must be able to supply an additional 5V.

A BA3xx series indicator may be connected in series with a 2-wire intrinsically safe transmitter to display the current and hence the process variable in engineering units. Fig 4A illustrates the use of a 2-channel Zener barrier, or two separate barriers as the intrinsically safe interface. Zener barriers are usually less expensive than galvanic isolators but do not provide isolation and require a high integrity earth which if not already available may be expensive to install.Fig 4A Transmitter loop powered via Zener barriers Considering the voltage drop around the loop in Fig 4A.

The instrument power supply must therefore have an output above 22.6V but below 25.5V which is the maximum working voltage of the 28V 93mA Zener barrier.
Fig 4B illustrates the same loop using a galvanic isolator as the intrinsically safe interface. Galvanic isolators although more expensive than Zener barriers allow a non-floating power supply to be used, do not require a high integrity earth connection and in general are easier to apply. It is usually only necessary to read the manufacturers specification to determine the voltage available to power the hazardous area loop. Fig 4B Transmitter loop powered via galvanic isolator

Remote indication
BA3xx series indicators may also be driven via an intrinsically safe interface from a 4/20mA safe area signal to provide a remote indication within a hazardous area. The type of interface is not critical, a Zener barrier, galvanic isolator or associated apparatus may be used, but again output parameters of the interface must not exceed the indicator’s maximum input safety parameters. Zener barriers are the least expensive interface particularly if a high integrity earth is already available. If one side of the 4/20mA current loop may be earthed, a single channel Zener barrier provides the lowest cost protection. If the 4/20mA signal is not isolated, two Zener barriers, a two channel Zener barrier or a galvanic isolator must be used. Again it is necessary to ensure that the voltage capability of the 4/20mA signal is sufficient to drive the indicator plus the voltage drop introduced by the intrinsically safe interface. Fig 5 shows the three alternative circuits which may be used.
Display backlight
All BA3xx series indicators can be supplied with an optional factory fitted display backlight that has three terminals allowing it to be loop or separately powered.

Loop powering the backlight
When loop powered, the backlight produces green background illumination enabling the indicator display to be read at night and in poor lighting conditions. Loop powering does not require an additional power supply, intrinsically safe interface or field wiring, but the maximum indicator voltage drop in the 4/20mA loop is increased from 1.2 to 5.0V. Backlight brilliance is constant between 6 and 20mA but slightly diminishes below 6mA.
Note: BA326C backlight can not be loop powered

The indicators backlight terminals 12(+) and 13(-) should be connected in series with the indicator’s 4/20mA input terminals as shown in Fig 6.
Any of the circuits shown in sections 7.1 and 7.2 may be used providing that 5V is available to power the indicator and the backlight.Fig 5 Alternative circuits for remote indication in a hazardous areasFig 6 Alternative circuits for BA3xx series indicator with loop powered backlight

Separately powering the backlight
Separately powering the backlight produces a slightly brighter green background illumination than loop powering. It enhances daylight viewing of the indicator display but an additional intrinsically safe interface and field wiring are required, the maximum voltage drop of the indicator in the 4/20mA loop remains at 1.2V.
The separately powered backlight is a current sink drawing a constant current when the supply between terminals 12(+) and 14(-) is above the minimum supply voltage.

Model

|

Current

| Minimum supply voltage

terminals 12 & 14

|
---|---|---|---
BA304G BA304G-SS BA304G-SS-PM BA324G BA324G-SS BA324G-SS-PM BA308E BA328E|

35mA

|

11V

|
BA307E BA327E BA307E-SS BA327E-SS|

23mA

|

9V

|
BA326C| See instruction manual|
 |  |

Table 3 Separately powered backlight voltage & current for each model Below the minimum supply voltage the backlight continues to function but the brilliance is diminished. For applications where operator’s night vision has to be preserved, adjusting the backlight supply voltage is a simple method of dimming the display backlight.
The backlight is segregated from all other circuits within the indicator and is separately powered via terminals 12(+) and 14(-) which may be connected to any intrinsically safe interface such as a certified Zener barrier, galvanic isolator or associated apparatus having output parameters equal to or less than:

• Uo ≤ 30V dc
• Io ≤ 200mA
• Po ≤ 0.84W

The maximum equivalent capacitance and inductance between the backlight terminals is:

• BA3xxE BA3xxG BA326C
• Ci = 13nF 3.3nF 30nF
• Li = 0.01mH 0.01mH 0.01mH

To determine the maximum permissible backlight cable parameters these figures should be subtracted from the specified Co and Lo of the Zener barrier, galvanic isolator or associated apparatus powering the backlight. Fig 7 shows an example of a Zener barrier separately powering the backlight.Fig 7 BA3xx series indicator with separately powered backlight
Two separately powered BA307E or BA327E indicator backlights may be connected in parallel to a single channel 28V, 93mA Zener barrier or galvanic isolator with no noticeable reduction in brilliance on a 24V dc supply.

Optional Alarms
All BA3xx series indicators can be supplied with two factory fitted single pole solid state alarm outputs. Each output is galvanically isolated and has been certified as a separate intrinsically safe circuit complying with the requirements for simple apparatus making it easier to use in intrinsically safe circuits.
Each output may be individually configured as a high or a low alarm with a normally open or a normally closed ‘contact’. Fig 8 illustrates the conditions available and shows which are ‘fail safe’. i.e. output is in alarm condition (‘contact’ open) when the 4/20mA input current is zero.

Fig 8 Alarm outputs
These alarm outputs are not suitable for use in critical safety applications such as a shut down system.
The equivalent electrical circuit of each alarm output is shown in Fig 9. Both outputs are polarised and will only pass current in one direction.

Fig 9 Equivalent circuit of each alarm output

Each alarm output is segregated and is a separate intrinsically safe circuit. It may switch any intrinsically safe circuit with output parameters equal to or less than:

• Uo ≤ 30V dc
• Io ≤ 200mA
• Po ≤ 0.84W

The maximum equivalent capacitance and inductance between the terminals of each alarm output is:

• BA3xxE BA3xxG BA326C
• Ci = 13nF 0 20nF
• Li = 0.01mH 0.01mH 0.01mH

To determine the maximum permitted circuit cable parameters, these Ci and Li parameters, plus those of any other device in the circuit, should be subtracted from the Co and Lo of the certified Zener barrier, galvanic isolator or associated apparatus powering the alarm circuit.
The alarm outputs may be used to switch intrinsically safe loads within the hazardous area or to switch safe area loads via a Zener barrier or a galvanic isolator. Fig 10 illustrates how one alarm output of a BA3xx series indicator can switch a certified intrinsically safe solenoid valve located in the hazardous area and the other alarm output can control a pump in the safe area via a switch transfer galvanic isolator. Fig 10 Typical alarm application
When an indicator alarm output is used to activate an annunciator such as a flashing beacon or a sounder one of the indicator push buttons may be configured to operate as an alarm ‘accept’ button. This allows the operator to silence the alarm for a configurable time up to 3,600 seconds in 1 second increments. If the alarm condition is not corrected during the silence time, the alarm will be reactivated.

SPECIAL FUNCTIONS

All BA3xx series indicators include special functions that extend their applications.

Square root extractor
All the BA3xx series indicators contain a square root extractor that allows the output from non-linearised differential flow transmitters to be displayed in linear units. The root extractor is selectable from within the indicator’s configuration menu using the instrument’s push buttons.

Lineariser
The integral lineariser enables BA3xx series indicators to display non-linear variables in linear engineering units. The function provides a sixteen point fully adjustable straight line lineariser which may be conditioned on-site to compensate for most non-linearities. Fig 11 shows an example in which a BA3xx series indicator displays the contents of a horizontal cylindrical tank in linear volumetric units from the 4/20mA output of a level transmitter. The internal indicator lineariser converts the tank level 4/20mA signal into a linear display of the volume being stored in the tank.
The lineariser can be adjusted on-site via the instruments push buttons, or if the curve parameters are specified when the indicator is ordered, it can be supplied calibrated.Fig 11 Lineariser enables tank contents to be displayed in linear units of volume

Tare
Primarily intended for use with weighing systems, the tare function replaces the percentage function on the indicator. When the tare push button is operated for more than three seconds the indicator display is set to zero and the tare annunciator activated, thus subtracting the current display from subsequent displays. When used with a weighing system, this function subtracts the displayed weight of an empty container from the weight of the container plus contents, so that the net weight of the contents is displayed. Subsequent operation of the tare push button for less than 3 seconds will return the indicator to the gross display and deactivate the tare annunciator.

RUGGED PANEL INDICATOR APPLICATIONS

These rugged panel mounting indicators have the same IECEx, ATEX and UKCA certification as the other models and may be used in any of the applications shown in section 7 of this guide. They have impact and IP66 ingress resistant front panels and are ideal for use in harsh environments or where the front of the instrument is likely to be impacted.
In addition these rugged indicators have certification allowing them to be installed into an aperture in a certified Ex e, Ex p or Ex t panel enclosure located in Zone 1, 2, 21 or 22 without invalidating the panel enclosure’s certification. This enables a rugged indicator to display a process variable in a hazardous area panel providing protection for equipment such as Ex e motor controls for a compressor.
The small rugged indicators BA307E-SS and BA327E-SS and the larger BA304G-SS- PM and BA324G-SS-PM have different certifications and installation requirements. Therefore each type is described separately.
BA307E-SS and BA327E-SS
Both instruments are housed in rugged cast 316 stainless steel cases with a 10mm thick toughened glass window. The joint between the instrument case and the panel enclosure in which it is mounted is sealed with a captive silicone gasket. After high and low temperature thermal endurance ageing, followed by impact testing at low and high temperatures, notified body Intertek issued the stainless steel case with component certificates IECEx ITS14.0007U, ITS14ATEX17967U and ITS21UKEX0094U confirming that the front of the case provides IP66 ingress protection and complies with Ex e, Ex p and Ex t impact and ingress requirements. These IECEx, ATEX and UKCA component certificates supplement the Ex ia intrinsic safety certificates ITS14ATEX28077X, IECEx ITS14.0048X and ITS21UKEX0095U for the BA307E-SS and BA327E-SS indicators which specify special conditions for safe use when installed in an Ex e, Ex p or Ex t panel enclosure.
Installation in an Ex e panel enclosure
Installation of a BA307E-SS or BA327E-SS indicator in an Ex e IIC Gb increased safety panel enclosure does not invalidate the Ex e panel’s certification, but the indicator remains Group II Category 1G Ex ia IIC T5 Ga intrinsically safe apparatus, therefore it must be powered via a Zener barrier or galvanic isolator as described in section 7 of this guide.
The Zener barrier or galvanic isolator is usually installed in the safe area but some intrinsically safe interfaces are certified for mounting within a protective enclosure located in Zone 2 which may permit them to be mounted in the same Ex e enclosure as the rugged indicator. Where the Zener barrier or galvanic isolator may be located is defined by its Type Examination certificate or IECEx Certificate of Conformity. Zener barriers and galvanic isolators are not permitted in Ex e enclosures located in Zone 1.

For personnel safety and prevention of an electrostatic charge, rugged indicators should be electrically connected to the panel enclosure in which they are mounted, or to a local bonding point if the panel enclosure is non- conductive. The indicator terminals, the wiring to the indicator and the intrinsically safe interface, if mounted within the enclosure, should be segregated from all other non-intrinsically safe wiring and equipment within the panel enclosure.
Required segregation distances are defined in standards EN 60079-11 Equipment protected by intrinsic safety and EN 60079-14 Electrical installations design, selection and erection. Terminals for intrinsically safe circuits should be segregated by at least 50mm from terminals for non-intrinsically safe circuits and from bare electrical conductors.
The intrinsically safe terminals and wiring should be identified and, if live maintenance is to be performed, any bare live non-intrinsically safe parts within the panel enclosure should be covered and labelled ‘Non-intrinsically safe circuit’ to prevent accidental contact.Fig 12 Typical installation in an Ex e panel enclosure

Fig 12 shows a BA307E-SS or BA327E-SS rugged indicator installed in an Ex e panel enclosure located in Zone 1 or 2. The 4/20mA cable should be sealed with an Ex e certified gland where it enters the Ex e panel enclosure and the cable screen should be earthed to a common point in the safe area such as the plant’s equipotential conductor, or to the Zener barrier busbar when barriers are used. To prevent fault currents from other equipment installed in the Ex e enclosure flowing to earth via this cable screen, it should be insulated in the hazardous area and should not be connected to the Ex e enclosure.
The power dissipation within an indicator fitted with alarms and a backlight which is separately powered is normally about 350mW, in the very unlikely event that all four circuits fail to the worst case condition at the same time, the total power dissipation rises to 3.4W which could raise the internal temperature of a small thermally well insulated panel enclosure.

Installation in an Ex p panel enclosure

Installation of a BA307E-SS or BA327E-SS rugged indicator in an Ex p panel enclosure does not invalidate the Ex p panel enclosure’s ingress or impact protection as the front of the rugged indicators comply with the Ex p ingress and impact requirements.
Because the BA307E-SS and BA327E-SS front panel push button contacts are outside of the pressurised panel enclosure, these two indicators remain Group II Category 1G Ex ia IIC T5 Ga intrinsically safe apparatus and may only be connected to an appropriate intrinsically safe circuit, even when mounted in an Ex pxb or Ex pzc panel enclosure which reduce the equipment protection level (EPL) inside the enclosure from Gb (Zone 1) to non-hazardous.
Both indicators have four rear panel vents to ensure that a potentially explosive gas is not trapped within the instrument case, when installed in an Ex p panel enclosure these vents, which are shown in Fig 13, should not be obstructed. Fig 13 Position of vents in BA307E-SS & BA327E-SS

For personnel safety and prevention of an electrostatic charge, BA307E-SS & BA327E-SS rugged indicators should be electrically connected to the panel enclosure in which the indicator is mounted, or to a local bonding point if the panel enclosure is non-conductive. The indicator terminals, the wiring to the indicator and the intrinsically safe interface, if mounted within the enclosure, should be segregated from all other non-intrinsically safe wiring and equipment within the panel enclosure. Required segregation distances are defined in standards EN 60079-11 Equipment protected by intrinsic safety and EN 60079-14 Electrical installations design, selection and erection. Terminals for intrinsically safe circuits should be segregated by at least 50mm from terminals for non-intrinsically safe circuits and from bare electrical conductors. Fig 14 Typical installation in Ex p panel enclosure
BA307E-SS and BA327E-SS rugged indicators may be installed in all three types of pressurised panel enclosure, Ex pxb, Ex pyb and Ex pzc as shown in Fig 14. The 4/20mA cable should be sealed by a gland which maintains enclosure integrity where it enters the Ex p enclosure and the cable screen should be earthed in the safe area to a common point such as the plant’s equipotential conductor, or to the Zener barrier busbar when barriers are used.
To prevent fault currents from other equipment installed within the Ex p enclosure flowing to earth via this cable screen, it should be insulated in the hazardous area and should not be connected to the Ex p enclosure.

Ex pxb panel enclosure
When pressurised an Ex pxb enclosure reduces the equipment protection level (EPL) inside the enclosure from Gb (Zone 1) to non-hazardous. When the Ex pxb panel enclosure is located in Zone 1, a BA307E-SS or BA327E-SS rugged indicator installed in the enclosure may only be connected to an Ex ia or Ex ib intrinsically safe circuit which will usually have it’s intrinsically safe interface located in the safe area. Alternatively, a suitably certified intrinsically safe interface such as a Zener barrier, galvanic isolator or associated apparatus may be mounted within the Ex pxb enclosure with the indicator. Where the certified intrinsically safe interface may be installed is defined by it’s Type Examination Certificate or IECEx Certificate of Conformity.

Ex pzc panel enclosure
When pressurised an Ex pzc enclosure reduces the equipment protection level (EPL) inside the enclosure from Gc (Zone 2) to non-hazardous. When the Ex pzc panel enclosure is located in Zone 2 a BA307E-SS or BA327E-SS rugged indicator installed in the enclosure may only be connected to an Ex ia, Ex ib or Ex ic intrinsically safe circuit which will usually have it’s intrinsically safe interface located in the safe area. Alternatively, a suitably certified intrinsically safe interface such as a Zener barrier, galvanic isolator or associated apparatus may be mounted within the Ex pzc enclosure with the indicator. Where the certified intrinsically safe interface may be installed is defined by it’s Type Examination Certificate or IECEx Certificate of Conformity.

Ex pyb panel enclosure
When pressurised an Ex pyb enclosure reduces the equipment protection level (EPL) inside the enclosure from Gb (Zone 1) to Gc (Zone 2). When the Ex pyb panel enclosure is located in Zone 1 a BA307E-SS or BA327E-SS rugged indicator installed in the enclosure may only be connected to an Ex ia or Ex ib intrinsically safe circuit which will usually have it’s intrinsically safe interface located in the safe area. Alternatively, a suitably certified intrinsically safe interface such as a Zener barrier, galvanic isolator or associated apparatus may be mounted within the Ex pyb enclosure. Where the certified intrinsically safe interface may be installed is defined by it’s Type Examination Certificate or IECEx Certificate of Conformity.

Ex t panel enclosure
Installation of a BA307E-SS or BA327E-SS rugged indicator in a certified Ex t (dust ignition protection by enclosure) panel enclosure does not invalidate the Ex t panel’s impact and ingress protection as the front of both indicators comply with Ex t impact and ingress requirements. However, because the indicator’s front panel push button contacts are outside of the enclosure the rugged BA307E-SS or BA327E-SS may only be connected to an appropriate intrinsically safe circuit, Ex ia or ib for Zone 21 installations and Ex ia, ib or ic for Zone 22 installations. Any of the circuits shown in section 7 of this Application Guide may be used.

The Zener barrier, galvanic isolator or associated apparatus is usually installed in the safe area. Alternatively, a suitably certified intrinsically safe interface such as a Zener barrier, galvanic isolator or associated apparatus may be mounted within the Ex t enclosure. Where the certified intrinsically safe interface may be installed is defined by it’s Type Examination Certificate or IECEx Certificate of Conformity.
The 4/20mA cable should be sealed by a certified gland where it enters the Ex t enclosure and the cable screen should be earthed in the safe area to a common point such as the plants equipotential conductor, or to the Zener barrier busbar when barriers are used. To prevent fault currents from other equipment installed within the Ex t enclosure flowing to earth via this cable screen, the screen should be insulated in the hazardous area and should not be connected to the Ex t enclosure.
Both indicators have an earth stud adjacent to the terminals on the rear panel. For personnel safety and prevention of an electrostatic charge this should be electrically connected to the panel enclosure in which the indicator is mounted, or to a local bonding point if the panel enclosure is non- conductive.
The indicator terminals, the wiring to the indicator and the intrinsically safe interface, if mounted within the enclosure, should be segregated from all other non-intrinsically safe wiring and equipment within the panel enclosure. Required segregation distances are defined in standards IEC 60079-11 Equipment protected by intrinsic safety and IEC 60079-14 Electrical installations design, selection and erection. Terminals for intrinsically safe circuits should be segregated by at least 50mm from terminals for non-intrinsically safe circuits and from bare electrical conductors.
The intrinsically safe terminals and wiring should be identified and if live maintenance is to be performed any bare live non-intrinsically safe parts within the panel enclosure should be covered and labelled ‘Non-intrinsically safe circuit’ to prevent accidental contact.
The power dissipation within an indicator fitted with operational alarms and a backlight which is separately powered is normally about 350mW, in the very unlikely event that all four circuits fail to the worst case condition at the same time, the total power dissipation rises to 3.4W which could raise the internal temperature of a small thermally well insulated panel enclosure.

Installation in the USA and Canada
The BA307E-SS and BA327E-SS rugged indicators have the following FM and cFM intrinsic safety certification permitting installation in both Divisions and Zones in the USA and Canada.

Class I Division 1 Groups A, B, C & D T5
Class I Zone 0 AEx ia IIC T5
-40ºC ≤ Ta ≤ +70ºC
When connected to a suitable system these rugged panel mounting indicators may be installed in:
Division 1
Explosive gas air mixture likely to occur in normal operation.
Division 2
Explosive gas air mixture not likely to occur, and if it does will only exist for a short time.

Be used with gases in groups:

• Group A Acetylene
• Group B Hydrogen
• Group C Ethylene
• Group D Propane

In gases that may safely be used with equipment having a temperature classification of:

• T1 450°C
• T2 300°C
• T3 200°C
• T4 135°C
• T5 100°C

At an ambient temperature between -40°C and +70°C.
For installations of these rugged indicators in the USA and Canada the intrinsically safe circuits shown in this Application Guide may be used providing the Zener barriers and galvanic isolators have local approval and the installation complies with the BEKA Control Drawing CI300-72. A copy of this Control Drawing is included in the BA307E-SS and BA327E-SS instruction manual which may be downloaded from the BEKA website.
Section 14 of the FM and cFM intrinsic safety Control Drawing CI300-72 states that when correctly installed in an AEx e, AEx p or AEx t panel enclosure, the rugged BA307E-SS and BA327E-SS indicators will not invalidate the enclosure certification.
Installation recommendations for these rugged indicators in Ex e, Ex p and Ex t enclosures described in sections 9.1.1 to 9.1.6 of this guide may therefore also be used for similar installations in the US and Canada, but the installation must comply with the local code of practice.

Note: Certified AEx e, AEx p and AEx t enclosures may only be installed in areas with zoned classification, not in areas with division classification.

BA304G-SS-PM and BA324G-SS-PM
These rugged 4 and 5 digit indicators are similar to the rugged BA307E-SS and BA327E-SS, but have larger displays. They have a cast 316 stainless steel front panel with a toughened glass window, the joint between the instrument case and the panel enclosure in which the indicator is mounted is sealed with a silicone gasket. After high and low temperature thermal endurance ageing followed by impact testing at below the minimum and above the maximum service temperature, notified body Certification Management Ltd issued component certificates 18ATEX3128U and 29U and IECExCML18.0071U confirming that the front of the enclosure provides IP66 ingress protection and complies with Ex e, Ex p and Ex t impact and ingress requirements. These IECEx and ATEX component certificates supplement the Ex ia intrinsic safety certificates for the indicators IECEx ITS11.0014X , ITS11ATEX27253X and ITS21UKEX0087X.

Installation in an Ex e panel enclosure
Installation of a BA304G-SS-PM or BA324G-SS-PM indicator in an Ex e IIC Gb increased safety panel enclosure does not invalidate the Ex e panel’s certification, but the indicator remains Group II Category 1G Ex ia IIC T5 Ga intrinsically safe apparatus, therefore it must be powered via a Zener barrier or galvanic isolator as described in section 7 of this guide.
The Zener barrier or galvanic isolator is usually installed in the safe area but some intrinsically safe interfaces are certified for mounting within a protective enclosure located in Zone 2 which may permit them to be mounted in the same Ex e enclosure as the rugged indicator. Where the Zener barrier of galvanic isolator may be located is defined by its Type Examination certificate or IECEx Certificate of Conformity. Zener barriers and galvanic isolators are not permitted in Ex e enclosures located in Zone 1.
For personnel safety and prevention of an electrostatic charge, rugged indicators should be electrically connected to the panel enclosure in which they are mounted, or to a local bonding point if the panel enclosure is non- conductive.

The indicator terminals, the wiring to the indicator and the intrinsically safe interface, if mounted within the enclosure, should be segregated from all other non-intrinsically safe wiring and equipment within the panel enclosure. Required segregation distances are defined in standards EN 60079-11 Equipment protected by intrinsic safety and EN 60079-14 Electrical installations design, selection and erection. Terminals for intrinsically safe circuits should be segregated by at least 50mm from terminals for non-intrinsically safe circuits and from bare electrical conductors.
The intrinsically safe terminals and wiring should be identified and if live maintenance is to be performed any bare live non-intrinsically safe parts within the panel enclosure should be covered and labelled ‘Non-intrinsically safe circuit’ to prevent accidental contact.

Installation of a BA304G-SS-PM or BA324G-SS-PM rugged indicator in an Ex e panel enclosure located in Zone 1 or 2 is shown in Fig 15. The 4/20mA cable should be sealed with an Ex e certified gland where it enters the Ex e panel enclosure and the cable screen should be earthed to a common point in the safe area such as the plant’s equipotential conductor, or to the Zener barrier busbar when barriers are used. To prevent fault currents from other equipment installed in the Ex e enclosure flowing to earth via this cable screen, it should be insulated in the hazardous area and should not be connected to the Ex e enclosure.

Fig 15 Typical installation in an Ex e, Ex p or Ex t panel enclosure

The power dissipation within an indicator fitted with operational alarms and a backlight which is separately powered is normally about 350mW, in the very unlikely event that all four circuits fail to the worst case condition at the same time, the total power dissipation rises to 3.4W which could raise the internal temperature of a small thermally well insulated panel enclosure.
For personnel safety and to prevent the accumulation of an electrostatic charge, the stainless steel front panel should be electrically connected to the panel enclosure in which the indicator is mounted by fitting a ring tag under one of the four rear of panel fixing screws.

Installation in an Ex p panel enclosure
Installation of a rugged BA304G-SS-PM or BA324G-SS-PM indicator in an Ex p panel enclosure does not invalidate the Ex p panel enclosure’s ingress or impact protection as the front of the rugged indicators comply with the Ex p ingress and impact requirements.
Unlike the smaller BA307E-SS and BA327E-SS rugged indicators, the front panel push button contacts of the BA304G-SS-PM and BA324G-SS-PM are within the rugged indicator, and hence inside of the pressurised panel enclosure. Therefore, when installed in a Ex pxb or Ex pyz pressurised enclosure which reduces the equipment protection level EPL inside the enclosure to non- hazardous, a rugged BA304G-SS-PM or BA324G-SS-PM indicator does not require protection by a Zener barrier, galvanic isolator or intrinsically safe output from associated apparatus. The installation should comply with requirements of IEC 60079-2 Equipment protection by pressurised enclosure.
For personnel safety and to prevent the accumulation of an electrostatic charge, the stainless steel front panel should be electrically connected to the panel enclosure in which the indicator is mounted by fitting a ring tag under one of the four rear of panel fixing screws.

Ex pyb enclosure
When pressurised, an Ex pyb enclosure reduces the equipment protection level (EPL) inside the enclosure from Gb (Zone 1) to Gc (Zone 2). When correctly installed in an Ex pyb enclosure the indicator should be powered by an appropriately rated Zener barrier or galvanic isolator located in a safe area

Ex pxb enclosure
When pressurised, an Ex pxb enclosure reduces the equipment protection level (EPL) inside the enclosure from Gb (Zone 1) to non-hazardous. When correctly installed in an Ex pxb enclosure the indicator may therefore be used without a Zener barrier or galvanic isolator.
Ex pzc enclosure
When pressurised, an Ex pzc enclosure reduces the equipment protection level (EPL) inside the enclosure from Gc (Zone 2) to non-hazardous. When correctly installed in an Ex pzc enclosure the indicator may therefore be used without a Zener barrier or galvanic isolator.

Installation in an Ex t panel enclosure
Installation of a BA304G-SS-PM or a BA324G-SS-PM rugged indicator in a certified Ex t (dust ignition protection by enclosure) panel enclosure does not invalidate the Ex t panel’s impact and ingress protection as the front of both indicators comply with Ex t impact and ingress requirements.
Unlike the BA307E-SS and BA327E-SS indicators, the front panel push button contacts of the BA304G-SS-PM and BA324G-SS-PM are within the rugged indicator, and hence inside the Ex t panel enclosure.

Therefore when installed in an Ex t enclosure a rugged BA304G-SS-PM or BA324G- SS-PM indicator does not require protection by a Zener barrier, galvanic isolator or intrinsically safe output from associated apparatus but should comply with requirements of IEC 60079-31 Equipment dust ignition protection by enclosure.
The 4/20mA cable should be sealed by a certified gland where it enters the Ex t enclosure and the cable screen should be earthed in the safe area to a common point such as the plant’s equipotential conductor. To prevent fault currents from other equipment installed within the Ex t enclosure flowing to earth via this cable screen the screen should be insulated in the hazardous area and should not be connected to the Ex t enclosure.
For personnel safety and to prevent the accumulation of an electrostatic charge, the stainless steel front panel should be electrically connected to the panel enclosure in which the indicator is mounted by fitting a ring tag under one of the four rear of panel fixing screws.

10 BA326C combined analogue and digital indicator
The BA326C is a panel mounting analogue loop powered 4/20mA indicator with a small 4½ digital display. It has IECEx, ATEX and UKCA certification for use in a flammable gas with similar performance to the BA3xxE and BA3xxG series indicators. The BA326C can be used in all of the applications shown in this guide, but it does not have dust or North American certification and its optional backlight can only be separately powered.

IECEx code
Ex ia IIC T5 Ga -40ºC ≤ Ta ≤ +60ºC
ATEX and UKCA code
Group II Category 1G Ex ia IIC T5 Ga
-40ºC ≤ Ta ≤ +60ºC

Maximum equivalent capacitance and inductance between 4/20mA input terminals 1 and 3

• Ci = 20nF
• Li = 0.01mH

Backlight separately powered terminals 12 and 13

• Ci = 30nF
• Li = 0.01mH

Alarm terminals 8 & 9 and 10 & 11

• Ci = 30nF
• Li = 0.01mH

BEKA associates Ltd.
Old Charlton Road., Hitchin, Herts. SG5 2DA UK
Tel: (01462) 438301
e-mail sales@beka.co.uk
www.beka.co.uk
23/11/2022 issue 16

References

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