24Vdc power supply for intrinsically safe devices
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My foreign colleagues have bought me an intrinsically safe pressure sensor that requires an external 24VDC power supply; it outputs a 4-20mA signal. Since it is to be used in hazardous areas, isolation barriers are necessary for the signal output. But is a 24VDC power supply really required? I asked P+F’s technical staff, and they said there is no such product available. I need help!
Intrinsic safety equipment must be used in conjunction with a safety barrier; this is necessary to limit both the operating voltage of the equipment and its operating current. Without the safety barrier, the required safety standards cannot be met. Also, is the pressure sensor you mentioned a load cell? You can consult Mettler Toledo; they have intrinsically safe power supplies, so it’s not a big problem. I have worked in weighing and measurement, and I encountered such cases during this training.
24V intrinsically safe power supplies are available, but can’t a 24V power supply be used to create a 2-wire system?
I don’t understand. There are only sensors with 4 wires like this. The manufacturer’s documentation mentions an option that allows for cost-effective safety compliance, but there are intense discussions on forums regarding whether the power supply can also be made to meet safety standards
I think it’s like this: if the power supply itself is not located in an explosion-proof area, whether it is intrinsically safe or explosion-proof doesn’t really matter. As long as it is isolated by an intrinsically safe barrier, the power supplied to the instruments will have its current limited. However, whether this current level is sufficient for the instruments to function properly depends on the design of those instruments.