The explosion-proof solenoid coil itself cannot directly block the current. But it plays an important role in limiting the current and preventing the current from changing suddenly, thus indirectly playing a similar role in preventing the generation and spread of dangerous current, as follows:
1. Excessive limiting current
• Use high resistance materials: Explosion-proof solenoid coils usually use wires with higher resistance to wind the coils. According to Ohm’s law, for a given voltage, an increase in resistance results in a corresponding decrease in current. This can effectively limit the current passing through the coil, avoiding excessive heat or even danger caused by excessive current.
• Built-in protection element: Some explosion-proof solenoid coils are fitted with internal protection elements, such as thermal fuses. When the current exceeds a certain value, the fuse will be blow and the circuit will be cut off in time to prevent excessive current from causing damage to the coil and other components, and avoid possible dangerous situations such as electric sparks.
2. Prevent sudden current changes
• Utilizing inductance features: The solenoid coil has inductance features. When current passes through it, it will generate self-inductance electromotive force that hinders the change of current. The explosion-proof solenoid coil in the design and manufacture will give full consideration to this feature, so that it can be in the power supply on or off at the moment, slowing down the rise or fall of the speed of the current, to avoid sudden changes in the current generates too high an induced electromotive force, which prevents the generation of sparks and other energy release that can ignite explosive mixtures.
3. Filtering function
• In some circuits, explosion-proof solenoid coils are used in conjunction with components such as capacitors to play a filtering role. It can filter out high-frequency noise and interference signals in the power supply, making the current passing through more stable, reducing current fluctuations and abnormal changes, helping to prevent equipment malfunctions or failures that may be caused by unstable current, and improving the stability and safety of the system.
4. Combined with explosion-proof design
• Synergy of flameproof enclosures: For explosion-proof electrical equipment of flameproof type, the enclosure has sufficient strength and sealing to withstand the pressure of an explosion that may occur inside and to prevent the propagation of explosive flames and high temperatures into the surrounding explosive environment. The explosion-proof solenoid coil is installed in such a flameproof enclosure. Even if the coil generates some abnormal current due to a fault, the flameproof enclosure can isolate it from the external dangerous environment, thus playing a role of secondary protection.
• Role in intrinsically safe design: In intrinsically safe explosion-proof circuits, by strictly limiting the current, voltage and other parameters in the circuit, the electrical sparks and thermal effects generated by the equipment in normal operation or fault conditions are insufficient to ignite the explosive mixture. Explosion-proof solenoid coil as an important part of the circuit, the design and selection of its parameters to meet the requirements of intrinsically safe, thus ensuring the intrinsic safety performance of the entire circuit, fundamentally avoiding the possibility of an explosion triggered by current problems.
Although the explosion-proof solenoid coil itself can not directly block the current, but through its unique choice of materials, structural design and close cooperation with the explosion-proof design, in limiting the current is too large, to prevent sudden changes in the current, filtering effect and to enhance the overall performance of the explosion-proof and so on, play a vital role.
These functions together constitute the irreplaceable value of explosion-proof solenoid coils in safeguarding the safe operation of electrical equipment and preventing explosions from occurring, providing a solid guarantee for industrial production and personal safety. Therefore, the rational selection and application of explosion-proof solenoid coils is crucial in electrical designs involving explosive atmospheres.
