In response to industry inquiries seeking clarification of the applicable entity parameters for the BBL ISPS (Issues 4, 5 and 6), and noting:
Users are now directed to Clause 12.7.4(b) of AS/NZS IEC 60079.25:2022.
This clause states that those entity parameter values spark tested in accordance with AS/NZS 60079.11 and documented on the Certificate of Conformity IECEx ITA 14.0005X can be used directly without any need for de-rating.
If further information is required please contact IS_Power@ampcontrolgroup.com.
Issue 6 of the certificate of conformity for Burn Brite’s ISPS Mk2 (IECEx ITA 14.0005X Issue 6) has now been released. The revision comprises only of an expanded entity parameter set.
This revision is expected to be the final update of entity parameters for this product.
Burn Brite will no longer be manufacturing the ISPS Mk 2 to Issues 0, 1, 2 and 3 of IECEx ITA 14.0005X and so and has requested cancellation of these issues of the certificate.
This cancellation of Issues 0 to 3 does not affect the certification status of equipment manufactured prior to October 18, 2021.
Copies of the cancelled certificates can be found at:
Issue 0: https://www.iecex-certs.com/#/deliverables/CERT/20813/view
Issue 1: https://www.iecex-certs.com/#/deliverables/CERT/20833/view
Issue 2: https://www.iecex-certs.com/#/deliverables/CERT/20834/view
Issue 3: https://www.iecex-certs.com/#/deliverables/CERT/20835/view
Users are directed to the commentary on those certificates provided by the issuing ExCB clarifying the status of those certificates and the associated equipment.
In addition, Burn Brite is compiling a schedule setting out ISPS serial numbers and their corresponding certificate issue for the information of end users and this will be available on the website shortly.
As foreshadowed in previous postings (below), a new Issue 5 of IECEx ITA 14.0005X for the Burn-Brite ISPS MK2 has now been released. The latest issue of the certificate provides additional entity parameter sets providing enhanced compatibility with a wider range of intrinsically safe equipment.
In particular, the two right hand columns make provision for Co of 17.5 uF with a connected Lo of up to 55 uH (see conditions of use). This value of Co is greater than that afforded by any of the previous issues of the ISPS CoC.
The significance of a higher Co is that where multiple circuits are connected to the ISPS, the individual capacitances add in parallel, while the inductances diminish in parallel.
[Note that the key inductance to consider is the individual circuit with the largest Lc + Li.]
The intrinsically safe output parameters in Issue 5 are the same for all variants (i.e. current ratings) of the ISPS.
Burn-Brite will only manufacture to the latest Issue of the CoC: this means that Burn-Brite will be unable to manufacture or supply Issue 3 or earlier variants of the ISPS for new orders. On that basis, Burn-Brite recommends that all users of the ISPS Mk2 pre-emptively review their existing installations of the ISPS to check if the Issue 4 and/or Issue 5 units can be directly substituted into circuits that currently use Issue 3 or earlier variants. This checking should involve an audit of the IS entity parameters.
Issues 0 to 3 of IECEx ITA 14.0005X remain suspended for the time being, pending finalization of a number of administrative matters. There is no change to previous advice regarding continuing use of this equipment in hazardous areas. See https://ampcontrolgroup.com/burnbrite-isps-mk2-voluntary-suspension/.
If further information is required please contact IS_Power@ampcontrolgroup.com.
The revised certificate of conformity for the Burn Brite ISPS MK2 has now been released. Issue 4 of IECEx ITA 14.0005X can be found on the IECEx website at:
https://www.iecex-certs.com/#/deliverables/CERT/59340/view
The revised certificate incorporates a number of variations from previous issues of the CoC:
The intrinsically safe output parameters in Issue 4 are seen to be the same for all variants (i.e. current ratings) of the ISPS. This decision was prompted solely by expediency rather than any performance measures: the release of Issue 4 would otherwise have been further delayed had testing of individual variants been undertaken. Burn Brite anticipate revisiting those entity parameter sets after further testing with the ExCB/TL.
The publication of Issue 4 of IECEx ITA 14.0005X enables Burn Brite to recommence manufacture of the ISPS Mk2 to meet outstanding and future customer orders.
Issues 0 to 3 of IECEx ITA 14.0005X remain suspended for the time being, pending finalization of a number of administrative matters. There is no change to previous advice regarding continuing use of this equipment in hazardous areas. See below all previous updates.
If further information is required please contact IS_Power@ampcontrolgroup.com.
Burn Brite is fully engaged with ExTC and expects resolution of the ISPS Mk2 certification in January 2022.
The original Applicant initiated Suspension of the Burn-Brite ISPS Mk2 Certificates of Conformity (CoC) covered the following:
The suspension and subsequent investigation have focused on the apparently disparate results from spark testing of the power supply by three separate IECEx accredited Test Laboratories (TLs).
Note: It is fundamental to the IECEx (and ANZEx) Equipment Schemes that the test results obtained by accredited TLs are not subject to independent confirmation, verification or question by any other party, and so are assumed to be ‘infallible’. In that context, the testing undertaken by accredited TLs that informed the issuing of two separate CoCs (and their revisions) is given significant credence.
The question, then, is how can different outcomes be achieved by different TLs at different times?
It is helpful to consider the test arrangement in sequential three parts:
The Manufacturer has undertaken comprehensive audits of all aspects of the procurement, manufacture, assembly and routine testing of the ISPS MK2 power supply, with no errors or omissions found. The EUT in the most recent testing is, as far as can be ascertained, the same as that tested previously under the various CoC updates. The Manufacturer’s Ex QAR is current, with no outstanding nonconformances, and zero nonconformances in the most recent audit.
The configuration of the EUT is determined by the TL’s Test Engineer and guided by the relevant standard. Some test configurations test the ISPS as a complete unit, others partition the circuit and/or introduce intentional faults into the arrangement. See IEC 60079.11 for details.
The Test Reports provided by the TLs usually describe the general test arrangement, however the detailed test arrangements are not typically provided in the Test Report. [These are retained in Laboratory notes by the TL and not made available to the Applicant.] In this context, it can be difficult to ensure that the separate tests conducted on each occasion are undertaken in the exact same way, leaving the potential for variability in testing and inconsistent test outcomes.
Each of the previous spark testing sessions of the EUT have been undertaken with the same notional arrangements: lumped electrical elements (R, L and C) inserted between the ISPS and STA interconnected by laboratory cabling, with various instrumentation for measurement and monitoring.
Table 1 shows the resistance of various electrical network elements as measured by the Test Laboratories in recent testing:
| Element | Test Lab A | Test Lab B |
|---|---|---|
| Resistance of STA | 0.12 Ω | 0.1116 Ω |
| Inductance of STA | Not provided | 0.82 μH |
| Resistance of connecting cables | 0.05 Ω | 0.0506 Ω |
| Inductance of connecting cables | Not provided | 1.19 μH |
| Resistance of lumped inductor(s) | 0.05 Ω for 28 μH 0.13 Ω (for 105 μH) | 0.1348 Ω (28 μH) |
Table 1: Circuit parameters values used in recent STA tests by IECEx TLs.
The significance of the values in Table 1 can be appreciated by a recent experimental observation that an increase in resistance of 0.1 Ω in the electrical network in an otherwise identical test arrangement can be the difference between STA ignition and non-ignition.
The detailed parameters for test objects used in earlier issues of the Certificate of Conformity have not been able to be sourced.
It is readily apparent that the absence of detailed technical records of circuit parameters makes comparison of different test scenarios problematic.
If repeatability of test arrangements is to be assured, it is arguably most appropriate to parameterize a practical inductor in terms of its equivalent model:
(Similar models can be described for capacitive elements.)
The Spark Test Apparatus has been previously and widely acknowledged to have degrees of inherent uncertainty. The prescribed STA procedures seek to address these by various statistical strategies – for example testing for multiple/extended periods. See for example Annex B and Annex H of IEC 60079-11.
Where a system contains both lumped inductances and lumped capacitances, IEC AS/NZS 60079.25 already places significant restrictions on permissible values and adds a substantial additional factor of safety for linear power supplies. Where both the lumped inductance and the lumped capacitance are greater than 1% of the respective output parameters Lo and Co of the IS power supply then IEC AS/NZS 60079.25 already requires that the permissible output parameters are both divided by two.
The Burn-Brite ISPS Mk2 is a nonlinear power supply. It is not necessary to de-rate the permissible output parameters at outlined above for linear supplies.
Where existing ISPS Mk2 installations have applied the de-rating, the resulting system will be more conservative that necessary. No further action is needed in such cases.
In accordance with IECEx OD 209 Ed 1.0 Clause 4.2.1, Burn-Brite has voluntarily initiated suspension of Certificate of Conformity IECEx ITA 14.0005X [INTRINSICALLY SAFE POWER SUPPLY V2], effective from 18th October, 2021.
Furthermore, Burn-Brite has voluntarily suspended manufacture of the ISPS from 15th October, 2021, which preceded suspension of the Certificate of Conformity.
Burn-Brite has recently been made aware of a spark test result from a Test Laboratory that is, prima facia, inconsistent with particular IS parameter sets previously established in compliance testing.
Burn-Brite is exercising an abundance of caution in suspending this Certificate of Conformity pending investigation.
No, a safety issue does not exist with the power supplies already in use.
The investigation is only associated with the 12V 2.5A variant of the IS power supply, and then only associated with electrical loads where high inductance and very low resistance combine to present an effective short circuit. This type of load is generally impractical for a DC power supply in continuous operation as the power supply will electronically trip and reset.
Testing indicates the factor of safety for this highly specific load condition comfortably exceeds unity, and so is considered safe. [The default factor of safety is 1.5.]
The suspension is voluntary and (only) prevents Burn-Brite from continuing manufacture while the investigation is underway.
Under the IECEx Scheme rules, suspension of a certificate of conformity is very distinct from a cancellation of a certificate of conformity:
For avoidance of doubt, the certificate in question is suspended but is not cancelled.
Notwithstanding this provision, and in the interest of enhanced safety, Burn-Brite recommends that the technical guidance offered in this document be reviewed and considered as soon as is reasonably practical by end users.
As the suspension of manufacturing has preceded suspension of the Certificate of Conformity, Burn-Brite can assure the industry that there are no ISPS Mk2 products that are unable to continue to be used in the field.
Certificate IECEx ITA 14.0005X lists several variants of the IS power supply, namely:
| Item | Description |
|---|---|
| 159104 | PSU IS MK2 IECEx 12VDC 2.5A |
| 162087 | PSU IS MK2 IECEx 12VDC 1.0A |
| 162088 | PSU IS MK2 IECEx 12VDC 1.5A |
| 162089 | PSU IS MK2 IECEx 12VDC 2.0A |
| 169804 | PSU IS MK2 IECEx 12VDC 2.35A |
| 171103 | PSU IS MK2 IECEx 11.6VDC 2.5A |
| 172742 | PSU IS MK2 ATEX 12VDC 2.5A |
| 172743 | PSU IS MK2 ATEX 11.6VDC 2.5A |
| 172744 | PSU IS MK2 ATEX 12V 2.35A |
| 172745 | PSU IS MK2 ATEX 12V 2.0A |
| 172746 | PSU IS MK2 ATEX 12V 1.5A |
| 172747 | PSU IS MK2 ATEX 12V 1.0A |
The investigation is only associated with the 12V 2.5A variant of the IS power supply. However, all variants of the IS power supplies listed above are necessarily affected because they currently all appear on a single certificate of conformity. As a consequence, Burn-Brite are temporarily unable to manufacture any of those products listed.
The IECEx scheme has a rigorous and well-defined process that is automatically enacted if a safety issue is found or suspected. Those processes are executed independently of the manufacturer.
Burn-Brite has elected to voluntarily suspend the certificate and the manufacture of the affected product out of an abundance of caution.
All end users of equipment in hazardous areas are required to have IS audits and application documentation consistent with the requirements of IEC AS/NZS 60079.14 and IEC AS/NZS 60079.25 that verify the application parameters are within the bounds allowable under the Certificate of Conformity.
A certificate of conformity cannot remain in suspension indefinitely. Suspension is a temporary status, and Burn-Brite anticipate prompt re-instatement of the Certificate of Conformity once the investigation is completed.
The investigation is only associated with the 12V 2.5A variant of the IS power supply.
Burn-Brite has initiated the process to request a revised Certificate of Conformity that that will cover all power supply variants other than 12VDC, 2.5A. As soon as that revised certificate is available manufacturing of all variants other than 12VDC, 2.5A will resume.
Burn-Brite will notify the market and relevant parties as soon as manufacturing of these products has resumed, and are again available for purchase.
Manufacture of the 12VDC, 2.5A units will remain on hold until the suspension of certificate IECEx ITA 14.0005X is lifted.
Both cases will be expedited as a matter of priority.
The two most likely outcomes of the investigation are:
The 2.5A power supply is one of Burn-Brite’s most popular products, and the voluntary suspension will affect several large orders from customers nearing delivery. Unfortunately, these deliveries must be suspended whilst the investigation is underway.
Our records clearly identify those customers affected by the manufacturing suspension, and they will be contacted directly by Burn-Brite representatives to receive regular updates as investigations continue.
Burn-Brite has not taken the decision to suspend the Certificate of Conformity lightly, and is exercising extreme caution in the interest of safety. Burn-Brite apologises for the disruption our voluntary suspension may cause, and will work closely with affected customers to minimise the disruption within the constraints of the IECEx processes now enacted.
Burn-Brite will publish regular industry updates on progress as we work toward resumption of our certificate.
There is a large installed base of Burn-Brite power supplies across the various mining jurisdictions in Australia. To ensure any enquiry related to our voluntary suspension is responded to promptly and efficiently, please use the dedicated email contact IS_Power@ampcontrolgroup.com
Copies of this document (be they printed or downloaded) are not controlled. Latest information and industry updates will be maintained electronically at:
https://ampcontrolgroup.com/burnbrite-isps-mk2-voluntary-suspension/
Enquiries and requests for information that are not related to our voluntary suspension should continue to use our normal electronic product customer service portal CustomerService@ampcontrolgroup.com
