Intrinsic safety limit switch
Thread Content
For P+F intrinsically safe devices, should the junction box be non-explosion-proof, intrinsically safe, or explosion-proof? If the exterior is an intrinsically safe junction box and the interior contains a regular microcontact switch (mechanical), then is this limit switch intrinsically safe?
Intrinsic safety stems from the classification of explosion-proof electrical equipment manufactured in accordance with the GB 3836.4—2010 standard and designed for use in coal mines. Explosion-proof electrical equipment is divided into categories such as flameproof type, increased safety type, and intrinsic safety type. The characteristic of intrinsic safety type electrical equipment is that all of its circuits are intrinsic safety circuits, meaning that the electric sparks and thermal effects generated under normal operating conditions or specified fault conditions cannot ignite the specified explosive mixtures. In other words, such electrical appliances do not rely on an explosion-proof casing or filling material for protection; rather, the energy of electric sparks or thermal effects generated by their circuits during normal operation or in case of failure is less than 0.28 mJ – which corresponds to the minimum ignition energy at a gas concentration of 8.5%, the most explosive concentration
If the work area is not an explosion-proof zone, it is not necessary
Intrinsic safety applies to circuits. For intrinsically safe instruments, the junction boxes can be intrinsically safe and waterproof; this way, they still comply with explosion protection regulations even when used outdoors. Of course, it’s necessary to ensure that they are at least waterproof and dustproof.
Intrinsic safety and explosion protection. , simplicity and brutality are fine
For P+F intrinsically safe devices, should the junction box be non-explosion-proof, intrinsically safe, or explosion-proof? Reply: Under normal circumstances, an intrinsically safe P+F device requires an intrinsically safe junction box. It’s not the box itself that is intrinsically safe, but rather the fact that all components within the circuit of the corresponding P+F product meet the intrinsically safe requirements; only in this way does the product become intrinsically safe. If you use a non-intrinsic box, it means that the entire integrated product may no longer fall within the intrinsic category, which is nonsense. Intrinsic safety considers not your box but all the components integrated within it. If the exterior is an intrinsically safe junction box and the interior contains a regular microcontact switch (mechanical), then is this limit switch intrinsically safe? Reply: By \"intrinsically safe box,\" I understand it to mean that all the components inside the box are intrinsically safe. But even so, since mechanical switches are not intrinsically safe by nature, such use is absolutely prohibited; it goes beyond the scope of intrinsically safe design.
The limit switches for mechanical switches come in intrinsically safe versions.
When using intrinsically safe instruments, their control cables must also be intrinsically safe. Additionally, a safety barrier in the cabinet is needed to prevent the electrical power used within the instrument cabinet from affecting the intrinsically safe instruments on site.
Does our biogas system need to be explosion-proof? The company wants to save money.