Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 6 replies
  • Subscribers 32 subscribers
  • Views 829 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Buried cable temperature monitoring

Jam
Hi all,


I am aware of tell-tale temperature stickers that can be placed on cables, conductors etc where overload is suspected. However, once buried this would of course be rather hard to inspect, certainly on a regular basis!


Does anyone have any recommendations for cable temperature monitoring setups that could be retrofitted relatively simply and connected to an existing data acquisition system, posssibly to trigger load reduction if necessary but that might be the advanced course.


I'm thinking of a few thermocouple patches under wraparound sleeving for waterproofing, going into a suitable device above ground, but this kind of sensor isn't my area and I don't want to reinvent the wheel if possible.


Thanks in advance,


J
Parents
  • 0


    Is there an obvious 'pinch point' where the cable is least well cooled ? It is far easier to monitor a single point than along a length.  In tricky cases one can insulate a short section that is accessible to mimic the section of concern that you cannot reach, and instrument that instead so long as the environment  to be mimicked is known.  (I have not done this for power cables, but the physics should be the same.)


    In a live system you can really  only measure the external jacket temp, and make some assumptions about how the temperature offset between core and outer varies with the external insulation.

    For extreme examples you could have a cable in running water, and the external jacket temp would be very low, as the water is a good coolant,  but at (the very high) full power, the core would be 70C or whatever, and all the temperature drop is across the plastic of the cable. The other extreme would be  a cable that is very well lagged, or in still air, with a lower full power level. Here the core and jacket temps are much closer to each other because most of the temperature gradient is external to the cable. Another way to look at this, is that in the 2nd case  the plastic of the cable jacket is a better thermal conductor than the external lagging.


    Personally I have always found that real cables run a bit cooler than expected, assuming that grouping and routing methods have been correctly included in the  prediction, but that may just be my luck.

    M.



Reply
  • 0


    Is there an obvious 'pinch point' where the cable is least well cooled ? It is far easier to monitor a single point than along a length.  In tricky cases one can insulate a short section that is accessible to mimic the section of concern that you cannot reach, and instrument that instead so long as the environment  to be mimicked is known.  (I have not done this for power cables, but the physics should be the same.)


    In a live system you can really  only measure the external jacket temp, and make some assumptions about how the temperature offset between core and outer varies with the external insulation.

    For extreme examples you could have a cable in running water, and the external jacket temp would be very low, as the water is a good coolant,  but at (the very high) full power, the core would be 70C or whatever, and all the temperature drop is across the plastic of the cable. The other extreme would be  a cable that is very well lagged, or in still air, with a lower full power level. Here the core and jacket temps are much closer to each other because most of the temperature gradient is external to the cable. Another way to look at this, is that in the 2nd case  the plastic of the cable jacket is a better thermal conductor than the external lagging.


    Personally I have always found that real cables run a bit cooler than expected, assuming that grouping and routing methods have been correctly included in the  prediction, but that may just be my luck.

    M.



Children
No Data

Community Rules & Guidelines