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Technical science and now known as the "intrinsically safe" explosion-proof measures of standard sources, the two can be traced back to the coal mine gas dangerous area of the use of electrical devices. Commissioned by the Prussian mine gas Committee based test, in Aachen (Aachen Industrial University in 1886, 1898 in BVS for the follow-up tests still conclude: "every electric spark are able to cause an explosion." It is a basic research on the basis of the explosion of the Senghenydd coal mine explosion in October 14, 1913 (which led to the death of 439 people) by Wheeler. The study identified communication and instrumentation in the spark ignition limit laid the foundation for the test. This study results as the basis to formulate the British standard BSl259:1945. So far, the study result still is quote in full to the ATEX Directive 94 / 9 / EC requirements of the essential health and safety requirements in the test, the results show that in. Huilin and BVS, director of Pailin as a result of the close cooperation study, even in the VDE0170:1926 on provisions of the equipment can not be caused by explosion of sparks limit value.
1.Test device for DC power and industrial alternating current
The experimental apparatus used by Wheeler has been improved in many countries and has been further developed. In the UK, the device for "Brealdlash No.3"; in France, "Kclateur Rapide" and intrinsically safe test for national standards. According to reports, the Russian the device is with a rifle bullet shattered conductors and circuit interrupting Sparks - coincidentally, with the German proposal to wire avulsion, the same effect. Very early on to try to make the test program in the IEC technology level of international standardization. In 1967 during the IEC31G committee meeting, Prague, through the comparison of different test conclusions submitted, decided to a group of staff development by Siemens company in Berlin test device, test results. In the recording of the meeting, the circuit parameters are limited to 1.5V / 300V / 1H. The whole technical environment of the test device developed based on experience is the aim of the DC circuit or industrial AC circuit, which is usually used to control and measure the circuit.
At that time, used in hazardous locations of the device. There is no denying the fact that also had indeed used higher frequency. For example: for capacitance measurements or by keying frequency control (TFSK) method for data transmission. Subsequently, handheld wireless phones and other high frequency applications, but in this regard, the application of security is mainly related to power supply circuits and auxiliary capacitors and coils. In general, the decision not to carry out high-frequency components related to high frequency energy analysis.
Understanding of spark test device: the device in 1965 after standardization to join / 0171 VDE0170 and 1977 after standardized with the EN50020 and for inspection of intrinsically safe circuit.
The most important milestone is of cable and wire effect (for example: the research carried out by the Schebsdat, caused by the inductance ignition process of, for example: by Vogt research and Johonnsmeyer ignition spark energy conversion case with actual mutual influence of basic instructions, caused by a capacitor ignition process research.
To improve the repeatability of the test results and the adaptability of large current, the best treatment plan is put forward. For the applicability of the method, the special instructions (provision) for the upper bound (upper limit of the cut-off frequency) are avoided. At first, in this regard not caused too much to worry about, but with the increase of the use of radio equipment, with more high frequency were energy transmission, and taking into account the special industrial sites. For example: radio transmitter near the refinery, the problem exposed gradually.
2.Press IEC 60079 - 11 as a spark test device for a spark generator
The total test design idea is: in a conductor circuit and two conductor short circuit, spark is generated, this way contact, a contact and mutual movement and power under worst case conditions possible and with high return rate, anywhere may sparks. By the simple circuit ignition limit of a variety of published curves and comparing the gas air mixture minimum ignition energy of the known values, we can in test conditions can be derived using the spark test device circuit and the energy of the corresponding value. At this point, for example, in the excitation coil through to DC, the spark in the conversion of storage can often only 50%, and the other half consume in the power of resistance, the contact spring assembly of electric sensor and contact spring assembly itself.
In the circuit with the coil, the fact that the spark is formed during the contact break point and the break point is selected for the optimum value of the input to the spark energy. Finally, due to the increase of the induced voltage, the longer time to suppress the rapid removal of each other. The original design of the spark test apparatus, which clearly shows that the design was originally used for the DC power supply circuit test.
3.In the frequency range up to 100kHz, the intrinsically safe circuit power transmission
Early results show that when the frequency of the AC circuit is high, the electrical parameters of the required electrical parameters are increased. Because of this effect, showing obvious increase in the frequency of about 100kHz, is transmitted by high frequency of energy. The relationship between the intrinsically safe transmission and high frequency is initially by proposed in the basic principles of intrinsically safe power supply project, and later with the BVS in "high-frequency intrinsically safe power transmission limit determination of research" project get to be confirmed by further studies.
Consultation①