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 5 replies
  • Subscribers 34 subscribers
  • Views 695 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

back on the 'surge'

psychicwarrior

 Good morning to all.  Revisiting a surge issue please.

 

Imagine a final circuit (or it could be some equipment cabling e.g to radio mast but Im not familiar so prefer to use a final circuit as the example ) that is fed from a [upfront] SPD protected board . The circuit runs back outside  (across a zone boundary? ), overhead/buried, for some distance (e.g 100m or whatever)  to equipment that is in contact with earth.

 

  • is it true that circuit could introduce a ‘surge' back into the installation just as the DNO supply may at the origin ?
  • in such a case if true, would there need to be another SPD after the final circuit's OPD to cater for this **… or if not where would the SPD(s) go and across which conductors ?
  • what ‘surge’ levels coming back in to the installation might one expect ?

 

e.g. origin----SPD---DB/CU outdoor circuit OPD--- **additional SPD ------ overhead/buried run (100m) ---- [grounded?] outdoor equip (poss with local SPD)

 

Sorry in advance if I am not understanding well enough to ask a coherant question ! :-)

 

Thank you, Habs

Parents
  • 0

    Hmm. how to explain.

    All a traditional spd can do is to connect all 3 cores together at one point, so to the transient they behave as one.

    There is nothing stopping a voltage gradient along that one (three).

    Contrast with winding all 3 cores around a magnetic core  and exciting the core to make them the secondaries of a transformer - now all 3 wires add however many volts per turn* no of turns, but the difference between L and N is the same both before and after the addition.

    (if we add 100V onto L, N and E the differences stay the same - the SPD will not see any change and will not operate - but get something between the hot and cold versions of the E and it will not like it.)

    Mike.

Reply
  • 0

    Hmm. how to explain.

    All a traditional spd can do is to connect all 3 cores together at one point, so to the transient they behave as one.

    There is nothing stopping a voltage gradient along that one (three).

    Contrast with winding all 3 cores around a magnetic core  and exciting the core to make them the secondaries of a transformer - now all 3 wires add however many volts per turn* no of turns, but the difference between L and N is the same both before and after the addition.

    (if we add 100V onto L, N and E the differences stay the same - the SPD will not see any change and will not operate - but get something between the hot and cold versions of the E and it will not like it.)

    Mike.

Children
No Data

Community Rules & Guidelines