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For electrical mining electromagnetic flowmeters, explosion-proof safety is of paramount importance. At present, the main types of explosion-proof electrical products in our country are flameproof type and intrinsically safe type ； And only intrinsically safe equipment can be used in hazardous locations. Mine-used intrinsically safe products must undergo intrinsically safety performance tests, among which the intrinsically safe spark test is one of the most important test items. When the circuit is turned on or off, energy is released in the form of sparks. When the energy exceeds a certain critical value, it will ignite the explosive gas mixture, thereby causing an explosion. Intrinsic safety design aims to control the energy of electrical sparks generated by the circuit, thereby achieving the intrinsic safety of the circuit. Intrinsically safe circuits must remain safe both under normal operating conditions and in the event of failures, with any electrical sparks generated being insufficient to ignite explosive gases present in the surrounding environment. Intrinsically safe excitation circuit for electromagnetic flowmeters The excitation current of the sensor in an electromagnetic flowmeter represents a risk of generating electric sparks; therefore, if such flowmeters are to be used in underground applications, their excitation circuits must meet intrinsically safe requirements. The electrical part of the electromagnetic flowmeter sensor consists of 2 coils, whose electrical parameters are primarily resistance and inductance. The resistance value is 40–60Ω (with the two coils connected in series), while the inductance is 100–300mH; it is this inductance that represents a potential source of hazard. When current flows through an inductive coil, a magnetic field is generated within the coil; this magnetic field stores energy. When the circuit is disconnected, the energy stored in the coil is released in the form of sparks. Therefore, it is necessary to absorb or discharge the energy stored in the coil in order to meet the requirements for intrinsic safety. Shunt circuits are connected in parallel across the coils of the electromagnetic flowmeter in order to discharge the magnetic field energy stored in the coils, thereby reducing the energy of electrical sparks that occur during switching on and off. Under normal conditions, it does not affect the operation of the circuit; when the circuit is disconnected, it forms a discharge path with the coil, clamping the voltage at the forward voltage drop of the diode (around 0.7V). However, simple rectifier diodes are only suitable for DC circuits, that is, situations with unidirectional current. To avoid electrode polarization and eliminate interference from mains noise, electromagnetic flowmeters require excitation using low-frequency rectangular waves; thus, the excitation signal is a periodic bidirectional current. As a result, conventional diodes are not suitable for this application. Here, for electromagnetic flowmeters, we use a new type of transient voltage suppressor, which is a novel electronic component developed on the basis of zener diode technology. When sudden high-voltage surges occur across its terminals, it can rapidly reduce its impedance to a conductive state at an extremely high speed, thereby absorbing current and dissipating energy. Its features include fast response time, precise clamping, and strong discharge capacity. Most importantly, it can achieve bidirectional clamping and discharge, meeting the requirements for bidirectional excitation; it does not affect the normal operation of the electromagnetic flowmeter and also helps to suppress sparks. It effectively suppressed energy leakage. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content! http://www.yb1518.com/UploadFiles/2012717174126829.jpg