Standard on fuses / isolation protection for field intruments


Thread Starter


I have over 100 sensors that require 24 vdc. Does anyone know what is the industry standard on short circuit protection? Do I need a fuse disconnect on each sensor? And if so, fuse terminal blocks will do? Any direction to the industry standards is greatly appreciated. I am new to this SCADA industry....Thanks, bruce

bob peterson

There is no requirement to have short circuit protection on any individual sensor. It is solely a design decision to do so.

I know of no requirement for individual fuses.
Typical 24 Volt systems are limited in the amount of power they can deliver. I would group the inputs together i.e by machine and fuse it that way.

Another option is to have fuses out in the field with one common power supply to save on home run cables

If we knew a bit more about what your sensors are we might be able to suggest something better.
Thank you for your comments.

All of these sensors will be powered by 24vdc and draw low amps. The instruments include actuator valves, analytical sensors, pressure, flow, and temp sensor..including PLC...etc. These locations will be in remote areas with no humans around. So even if a fuse blows, I would have to trouble shoot the root cause and maybe remotely reset it. I know that there are remote resettable circuit breakers out there. So the million dollar question is whether to use a self resetting fuses (PTC) or Remotely reset CB. Therefore cost is an issue. If cost is not an issue, would it still make sense to have each electronics have a PTC or RRCB? How would I tackle this design?

Any comments or recommendation appreciated?