Iec 61641 Internal Arc
Jessica Wade
Low voltage and switching devices (Electric Panels) for factory, workshop, power plants, work places etc. provides the distribution and switching of electrical energy. Low voltage and switching devices (Electric Panels) differ according to their usage and purpose. Low voltage and switching devices (Electric Panels) internal arc condition may occur during use. The internal arc test is a type test intended to simulate such conditions. The internal arc test is a type test based on evaluating the ability of the assembled product to limit its risk of affecting its environment. Internal arc test is a type test for low voltage and switchgear (Electric Panels) produced in accordance with TS EN / IEC 61439-1 and TS EN / IEC 61439-2 standard.
The purpose of performing internal arc testing within the scope of the IEC 61641 standard is to determine the performance under the arc conditions caused by internal error for enclosed units that have completed type tests in accordance with IEC 61439 -1 and TS EN / IEC 61439-2. In this context, the phases are short-circuited by means of a conductive wire in the dimensions allowed by the standard to perform the internal arc test. Indicators are placed around the test specimen in accordance with the manufacturer's declaration during the internal arc test. These installed indicators represent the operator during normal operation. During the internal arc test, in case of internal error, there should be no damage to the indicators around the test sample.
Can we specify an internal arc withstand value of say for example 85 KA for 0.4 sec while the short circuit withstand specified for the assembly is 50 KA for 1 second . I assume yes we can if not can someone explain why not ?
Regarding your reply: "i may specify is 50 KA /0.4 or 50 KA/0.3 (if prospective maximum short circuit is 50 KA /1s)but for building up a safety margin i can specify 65 KA/.5 or 85 KA/0.4 or 100 KA/0.4 . And i may give reasoning to the customer that higher the internal arc withstand of a panel more safer is the panel ( irrespective of the maximum prospective short circuit current). Am i right here ?"
If I make a parallels explanation...suppose you buy a car. The car is able to run at 190km/h. The speed is limited at 130km/h on the highway. So do you have any chance to exceed 130km/h? No but it is comfortable, the result is when you drive the noise will be lower, the reliability higher, the safety also.
To an assembly it is the same thing. Probably in case of internal arc the impact into the assembly will be less important, probably the MTTR(mind time to repair) will be better...we call that a safety margin.
Suppose I am a specifier . I have designed a system where maximum short circuit possible is 50 KA and I mention in the specification that the LV assembly shall have a short circuit withstand capacity of 50 KA / 1sec . Now I wish to ensure that the LV assembly shall also be internal arc tested as per IEC /TR 61641 . So I go ahead and I mention in the specification that LV assembly shall be internal arc tested as per IEC/TR 61641 for a value of 85KA/0.4 sec or 100 KA/0.3 sec .
Regarding the level of short-circuit, as you said the maximum prospective short-circuit is 50KA. So, using your wording it is not logical to require an internal arc withstand exceeding this value but it will propose a safety margin.
Thank you for your explanation. I must admit you have addressed my query precisely . In order to assure myself that i have understood , wish to take your final opinion again along with an additional query .
You have mentioned in your response below "You minimum specification could be for internal-arc 50 KA/0,4s or 50 KA/0,3s and if you want a have a safety margin to that performance also 85 or 100 KA/0,4s"
so , this means minimum i may specify is 50 KA /0.4 or 50 KA/0.3 (if prospective maximum short circuit is 50 KA /1s)but for building up a safety margin i can specify 65 KA/.5 or 85 KA/0.4 or 100 KA/0.4 . And i may give reasoning to the customer that higher the internal arc withstand of a panel more safer is the panel ( irrespective of the maximum prospective short circuit current). Am i right here ?
However consultants are questioning on the building up of safety margin and ask under what circumstances can a current of 65 KA , 85 KA or 100 KA might flow in the system when maximum prospective short circuit current is 50 KA only ?
I am truly Delighted with the support extended and your patient response to my queries . Will be glad if you can share any related literature for my reference and use ( if you already have any) and once again thank you !
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In our clinical practice, we found that several patients who received a COVID-19 vaccine developed cardiac-related discomfort that did not meet the diagnostic criteria of myocarditis. Angeli et al. described the occurrence of an adverse reaction, hypertension after COVID-19 vaccination. According to the mechanism of the mRNA vaccine, free-floating S protein might expand a massive interaction with the ACE2 receptors leading to receptor degradation, which would subsequently contribute to hypertension14. Hence, a relationship between cardiac discomfort and COVID-19 vaccination is probable. The tissue tracking technique is a novel extension of the Doppler method that focuses on cardiac function, which allows identification of major cardiac changes in symptomatic individuals. Two-dimensional speckle tracking echocardiography (2D-STE) has been regarded as a promising tool for the evaluation of heart failure, coronary artery disease, myocardial dyssynchrony, valvular heart disease, and arrhythmia15,16,17,18,19. This modality is easily accessible, cost-effective, non-radiative, and non-invasive, with high sensitivity and specificity for LV functional assessment, and it can detect subclinical myocardial dysfunction early in the disease process20,21,22. In this regard, we hypothesized that the global strain of the myocardium, a cardiac mechanical parameter, can be used to assess subtle structural and functional changes indicating cardiac AEs in patients who received COVID-19 vaccines. This study aimed to evaluate the role of cardiac mechanics, particularly myocardial strain in the early assessment of the clinical presentations of cardiac manifestations after COVID-19 vaccine administration.
All patients underwent serological examinations. Laboratory data included thrombosis factors (platelet count and D-dimer) and cardiac inflammatory markers, such as creatine phosphokinase (CPK), creatine kinase myocardial band (CK-MB), Troponin T (TnT) and N-terminal pro b-type natriuretic peptide (NT-proBNP). Incidents of cardiac-related discomfort after vaccination were collected. Data validation was evaluated by two independent investigators to ensure the accuracy and consistency of the analysis.
Representative global longitudinal strain (GLS) and global circumferential strain (GCS) analysis. The myocardial strains were quantified as the peak systolic value in each myocardial segment. The upper and lower figures represent the peak systolic GLS and GCS, respectively. The most negative values, which are denoted by the white asterisks, were measured prior to aortic valve closure (AVC).
Our study was conducted in Taiwan since the early period of the COVID-19 pandemic. There were only a small number of COVID-19 infected patients here. None of our study population had the previous infection. Our study results showed that global myocardial strain, including longitudinal strain and circumferential strain, are sensitive, non-invasive, and reproducible indices that are clinically relevant to the subtle changes in the left ventricular myocardium that may occur as a consequence of the cardiac impact of COVID-19 vaccination. Hence, we found that the potential capability of tissue speckle tracking analysis can evaluate and indicate early myocardial dysfunction and adverse cardiac events after immunization with COVID-19 vaccines.
Various vaccine designs have been developed to elicit an immune response, which can be classified by the host-cell translation process. Non-replicating viral vector vaccines, mRNA vaccines, and protein subunit vaccines undergo the translation of nucleic acid into a modified S protein within the host cell to further enhance both humoral and cellular immunity31. Harrison et al. mentioned that the ACE2 receptor has a role as a cardiac function regulator, and is generally expressed in coronary endothelial cells, cardiac fibroblasts, and cardiomyocytes32. According to the mechanism of host cell entry in natural SARS-CoV-2 infection, it is possible that S proteins expressed by a vaccine can bind to ACE2 receptors and subsequently be internalized. Once clearance of the S protein with bound ACE2 by antibodies and immune complexes begins, RAS imbalance and enzymatic activity could reduce the overall availability of ACE2, eventually inducing vasoconstriction and increased blood pressure, leading to a burden on the heart, such as elevation of intraventricular volume and pressure, impacting ventricular function. Concurrently, this clearance elicits the formation of immune complexes, which would subsequently be eliminated by the macrophage-monocyte network and induce inflammation. This phenomenon could lead to serious consequences on the vessels and heart, particularly in vulnerable groups, such as patients with hypertension, arterial aneurysm, and atherosclerosis5,33.
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