Schau, Holger
Technishce Universitat Ilmenau
There is a general hazard and potential risk of human injury due to electric fault arcs which may internally occur with short-circuits in electric installations. These arcs cannot be avoided totally, the protection against the arc consequences is of largest importance for those people working at, in or in the vicinity of electrical installations and especially in case of live working.. Their clothing may essentially contribute to protect them particularly against the thermal arc hazards or be actually a base for the according protection.
There may not result any unacceptable health risk, the suitability of clothing has to be analysed and proved. A reliable test is necessary to confirm the working clothing to be arc resistant and guaranteeing the protective level required as well. A quantitative measurement of the incident energy is necessary for a classification and certification of the clothing. Test method, procedure, set-up and parameters must cover the practical needs and exposure scenarios. Protective clothing must be tested under practically relevant and reproducible conditions.
In the international standard IEC 61482 Part 1 there will be two methods for testing of protective clothing in next future.
The author is convenor of the IEC Project Teams preparing these standards.
One of these methods is the so-called Box Test using a directed electric arc in a low voltage test circuit to determine the protection class of materials and garments intended for use in heat- and flame-resistant clothing for workers exposed to electric arcs. This test was developed to have a practice-oriented test standard for protection classes that characterize safety requirements covering actual risk potentials due to electric fault arcs. The box test method has been used in testing and certificating of protective clothing in Europe for more than five years
In the paper the hazards of electric fault arcs are analyzed and, based on this, the requirements for practical tests are proved. The development in the international standardization in the field of protective clothing is considered. The according running IEC standard projects, the aims and contents of the new standards are explained. There will also come a product standard for arc thermal protective clothing. Practical conclusions and resulting consequences are pointed out. Furthermore experiences in the box test method will be discussed. The paper gives information on quality assurance of testing and on generalized results obtained during testing in the last six years.
