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 Post subject: Arc Hazard the European Approach
PostPosted: Wed Dec 09, 2020 11:34 am 

Joined: Wed Dec 09, 2020 10:40 am
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I am an Arc Hazard specialist from the Netherlands and have carried out many studies.
In Europe there is still a lot of confusion as to which method is the correct one.

In 2021, the new European standard EN 50110 is expected to provide more clarity. In expectation of the new European standard, I have written a brochure in which the danger of an Electric Arc relates to the European regulations.

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European Arc Hazard Approach.pdf [1.84 MiB]
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 Post subject: Re: Arc Hazard the European Approach
PostPosted: Wed Jan 06, 2021 2:21 am 
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Joined: Mon Jul 09, 2007 11:43 pm
Posts: 59
Location: Sheffield, England
I strongly disagree with the views expressed in this paper.

I speak from an independent viewpoint and base my reply on having been exposed to the debate about open arc versus box testing for many years. I have huge respect for the professional engineers and academics who have been forefront of arc flash research in Europe, however, I don’t think that they would be comfortable with this polarised and inaccurate view of arc flash risk management.

From the perspective of someone who has been responsible for system studies and arc flash calculations in over 16 countries for blue chip organisations in most sectors throughout Europe, this paper is completely misleading. It misrepresents the true situation where my clients have had no difficulty whatsoever in obtaining a CE mark for PPE based upon IEEE 1584 and the open arc test. The paper is suggesting the opposite to that experience. In addition, many electrical engineers see the box test as being inadequate for large industrial and commercial facilities.

Page 10 When a limitation becomes a characteristic. On page 10 it states that “An important characteristic of the Box test consists of the energy level limited to 400V, -7kA/0,5s.” This is a severe limitation of the test rather than a characteristic of the box test and to claim it as an advantage is somewhat disingenuous.

Page 10 continued. It goes onto say “A limitation of the energy level is required within the framework of the European directives. If the energy level increases, the hazards also increase. Hazards such as explosion pressure (arc blast) and toxic gases are a serious threat to human health. The available garments and PPE do not protect workers against these hazards”. Looking at IEC 61482-2, there is no upper limit assigned specifically to the box test APC2 as claimed. There is, however, a quoted limit for open arc ELIM rating.

Page 15. There is an example given of infra-red inspections on live equipment under the heading of “Avoiding Risks” which is very odd. In fact, under the same heading is the following list of methods to avoid the risk.

• Constructive measures in the installation design;
• Replacement or renewal of components and devices (retrofitting);
• Use materials and equipment suitable for the load;
• Using materials and equipment of better quality;
• Prevent incorrect handling;
• Measures in operational management (work permit)
• Proper maintenance of equipment;
• Carry out regular inspections.

Not one of these measures can be described as “avoiding risks”. Avoiding the risk for arc flash starts with Dead working, Not energised = No electrical danger. Not forgetting that there is risk associated with making dead, isolated (and earthed) and that needs managing.

Page 20 Risk Analysis. This is incorrect, what is shown here is not a risk analysis but rather a hazard analysis.

Page 21 The ISSA method (method 2, IEC 61482-2) does not “provide the best guarantee that employees are well protected against the thermal hazards of an electric arc”.

Page 21 The ISSA method does not “prevent personnel from being exposed to other hazards such as explosive pressure (arc blast) and toxic gasses”.

Page 22 The diagram suggests APC1 plus APC1 result in APC2? This is misleading as the expert view is that an APC1 garment worn on top of another APC1 garment may not achieve APC 2 and the combination would have to be tested to find the actual protection class.

Page 23 “When it comes to buying clothes and PPE, it's easy, there are only two choices, class 1 or 2.” – This statement is very misleading! I have found large sites that have used APC 1 for LV and APC 2 for HV in a mistaken belief that the higher the voltage, the higher the danger.

Page 25 – Example of a Detailed Calculation – I have questions about the figures shown.

1. What is the task that is being performed on a main switchboard that has to be carried out with the equipment live? The low fault level attenuation suggests that the switchboard is close coupled to the transformer.
2. The protective device is shown as a “breaker”. However, the disconnection time is shown as a pre-arcing time. Is this a breaker or is it a fuse?
3. If it is a fuse and the pre-arcing time is 0.05 seconds, what is the clearance time?
4. If it is a breaker what size is it and what are the settings?
5. Where is the breaker or fuse mounted? Is it in an integral device within the switchboard? If this is the device that is being relied upon to clear an arcing fault, is there a risk of a line side fault.
6. The calculation shows a minimum short circuit current I”k3p_min of 21kA and a short circuit current I”k3 of 22.11kA. I suspect that this has been obtained by multiplying the IEC 60909 voltage factor only. How has this figure has been obtained?
7. The Kt value is 1.7 meaning that the conductors are in air. Is this correct? On a switchboard? This seems very odd.
8. The other oddity is the transformer short circuit current of 24,056 amperes. This does not seem to tally with the impedance of 6%. What is the fault level on the primary? It looks to me that the infinite bus method has been used meaning an error of about 2000 amperes.

From a professional point of view, the risk assessment on sometimes highly complex and high-power electrical systems has to be performed to the latest standards which reflect the 5th Principle of Prevention for the European Framework Directive. This is Adapting to Technical Progress/Information and means that we take advantage of technological and technical progress to improve both safety and working methods. The evaluation of the hazard has progressed, as have mitigation and protection techniques in respect of arc flash. Whilst the box test largely emulates the conditions for a jointer working on a metering cut out, a professional engineer would need to be careful about basing his/her arc flash risk assessments on such a limited resource.

Mike Frain CEng FIET MCMI

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 Post subject: Re: Arc Hazard the European Approach
PostPosted: Mon Jan 11, 2021 7:23 am 
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Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1538
Location: Scottsdale, Arizona
Dutch Lucien wrote:
I am an Arc Hazard specialist from the Netherlands and have carried out many studies.
In Europe there is still a lot of confusion as to which method is the correct one.

You are correct, there is quite a bit of confusion regarding arc flash studies and protection. The posted guide “Arc Hazard – The European Approach” is a prime example with an apparent bias towards the box test method and BGI/GUV-1-5188E Guide. Many incorrect or misleading statements are made, whether intentional or not regarding IEEE 1584 and the open arc test IEC61482-1-1

I am Vice-Chair of IEEE 1584 and Chair of IEC TC78 Live Working which includes many of the standards that are listed in the guide including both IEC 61482-1-1, 61482-1-2 and 61482-2.
What follows does not represent any official position of the aforementioned standards, but are simply my personal observations to clarify some of the statements in the document.

Mike Frain's (a UK based colleague) earlier post brings some of this to light. I would like to add additional comments regarding this document. Mike and I authored a peer reviewed IEEE technical paper that was presented at an IEEE conference in January 2012. A European view of arc flash hazards The paper addresses the European approach based on many of the directives that your attached paper cites.

Page 8: and there is a tiny difference with the ASM 1959F test.
The standard is ASTM 1959F (minor typo)

Page 8: The test setup consists of 3 electrodes
Incorrect - The test method for 61482-1-1 uses TWO opposing electrodes

Page 8: The test parameters ATPV and EBT50 have a 50% probability of exceeding the Stoll curve., which could result in a second-degree burn. European regulations are based on 100% protection; therefore, these arc ratings are not suitable for the European market. Misleading Statement.

IEC61482-1-1 was specifically developed for the European market. The definition of Arc Rating according to IEC 61482-1-1 contains note 1 as clarification which states: The arc rating can be the arc thermal performance value (ATPV), the breakopen threshold energy (EBT) or the incident energy limit (ELIM)

Page 8: The ELIM test parameter has been introduced into the 2018 PPE standard, IEC 61482-2 and have been defined by not exceed the Stoll curve. Due to the fact that the ELIM rating has no limit, it does not meet the European requirements.

ELIM was developed for the express purpose of complying with European Requirements. CENELEC representation was part of the development specifically for that reason.

ELIM is NOT IEC 61482-2-2 specific. In fact, on Page 5 of the 2018 Edition of IEC 61482-2 that lists the changes in the 2018 edition, it specifically states: This edition includes the following significant technical changes with respect to the previous edition.

a) new definition for ELIM, ATPV and EBT as used in accordance with IEC 61482-1-1

Page 8: The incident energy (IE), measured by the sensors, is calculated for 30s after ignition of the arc. Misleading

The time period is taken out of context.
IEC 61482-1-1 states: 12.1.4 The comparison shall be made only in the time range starting at 1 s after arc initiation up to 30 s.

The 2018 IEEE 1584 standard DOES account for direct exposure via the Horizontal Electrode Configuration known as HCB. Incident Energy Calculations using HCB may result in incident energy 2 to 3 times greater than the original VCB method. I personally made a presentation at an IEEE conference comparing HCB calculations to arc rated fabric ratings that were tested with horizontal electrodes / more direct plasma exposure and the results using HCB were nearly identical. 2018 IEEE 1584 HCB Convective Flows

Video on the subject: Modify the Arc Rating or Modify the Incident Energy Calculations

BGI/GUV-1-5188E is a guide whereas IEEE 1584 is an International IEEE Standard that was developed over many years of empirically derived tests and was peer review by both IEEE 1584 Working Group Members and a separate group of IEEE members for the final approval.

The IEEE 1584 Standard testing was conducted by the NFPA/IEEE Arc Flash Collaboration which also had an international advisory board including the chief architect of the BGI/GUV-1-5188E Guide.

The equations and calculations methods provided by IEEE 1584 are based on several thousand arc flash tests and the equations were several years in development and with the input of the aforementioned advisory group. A separate model review group then rigorously evaluated and further enhanced the equations over another period of two years. Over 200 people were ultimately involved with the peer review and approval.

The IEEE 1584 calculations on page 19 do not provide much detail. For comparison, I performed the calculations using data that was provided for each of the three enclosure configurations, VCB, VCBB, HCB

My results using 2018 IEEE 1584 for the calculations at "Main 2"
VCB: 4.13 cal/cm^2,
VCBB: 6.21 cal/cm^2
HCB: 8.79 cal/cm^2.

My results using 2018 IEEE 1584 for the calculations at "Sub 2-3"
VCB: 11.95 cal/cm^2,
VCBB: 17.39 cal/cm^2
HCB: 25.42 cal/cm^2.

Again, reference the link and article above regarding the affect of HCB on arc rated clothing.

The IEEE 1584 Standard has been validated up to 15 kV based on actual tests. What was the maximum voltage used for tests for the BGI/GUV-1-5188E Guide? Was it actually 115 kV?

There is much more that I could add. It appears this document contains information that is misleading and taken out of context. Unfortunately it seems to serve the purpose of attempting to discrediting the use of IEC 61481-1-1 test method along with the global standard IEEE 1584 - both of which are used internationally on a large scale.

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