Is it necessary to shut off the power for on-site operations of chemical instrumentation?
Thread Content
As the question implies, chemical process instrument circuits are typically powered by 24V DC. Is it necessary to cut off the power during actual on-site maintenance work? In cases such as the complete removal of the valve feedback mechanism for cut-off valves or the complete removal of solenoid valves, where there is no exposure of cables, is it possible to proceed without shutting down the power supply? When disassembling a transmitter and it is necessary to untie wires, should one wire be untied after insulating it first, and then the next wire, and so on? Is it possible to carry out these tasks without shutting down the power supply? What is needed now is to know whether there are any relevant requirements in the regulations and standards; I hope someone with expertise can give some guidance. Thank you!
It’s not necessary, right? We used to just replace them directly, unless it’s 220V
Isn’t removing the stitches itself equivalent to cutting off the power? Many are circuits with direct output from the card units; to shut them down, one still has to disconnect the wires, after all – it’s not possible to cut off power to the entire cabinet or to all the card units at once. However, if this condition is met, it’s of course better to turn off the power first before proceeding.
No need; just ensure proper insulation
It is better to perform on-site maintenance with the power turned off; although a short circuit does not cause harm to people, it can damage the equipment.
If you ask, then power isolation is required; in some cases, an work order is even necessary. If you go to the site without asking first, then power isolation isn’t needed. Of course, I’m referring to 24V here
It seems to be maintenance work. Remember one thing: operations must be carried out in compliance with regulations, following the standard procedures strictly. Keep in mind that if you keep chasing geese all day long, you risk having your eyes pecked by them
If it is still safe to cut off the power at 220V, it is also recommended to do so in explosion-proof areas; in other cases, I don’t think it matters.
It’s sufficient to have a live disconnect; be sure to provide proper insulation protection to prevent contact with the casing, and install fuses.
It mainly depends on the workplace and environment; in ordinary locations, 24V intrinsically safe systems do not require power shutdown, while those with other explosion-proof ratings need power to be cut off. A short circuit at 24V can damage the wiring and fuses, leading to safety accidents.