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 11 replies
  • Subscribers 27 subscribers
  • Views 1010 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Regulation 534.4.4.6

MG
Greetings to the forum.

Can someone clarify this for me. Regulation 534.4.4.6 says:
"In general, the short-circuit current rating ISCCR of an SPD, as stated by the manufacturer, shall not be lower than the maximum prospective short-circuit current at the connection points of the SPD assembly"

Then Note 1 below the regulation says:
"The SPD alone, or as an assembly in conjunction with its disconnector and/or overcurrent protective device (OCPD), is required to withstand the short-circuit current rating ISCCR as stated by the manufacturer. This value is defined and tested according to BS EN 61643-11, in conjunction with the disconnector and/or OCPD as stated by the manufacturer"


I understand that ISCCR (in kA) is a short circuit withstand capability value given by the manufacturer on the condition the maximum upstream protective device rating is not exceeded.


If the upstream SPD protective breaker/fuse has a breaking capacity higher than the system fault level, can an SPD with a ISCCR lower than the system fault level be used? I am confused because Note 1 says either the SPD alone or SPD+Disconnector as an assembly has to withstand the system fault level.


Reason for all this scenario is because I have come across an SPD with short circuit withstand capability of 25kA protected upstream by a breaker with Icu of 50kA is specified on a system with 37kA fault level.


Thanks,

M.


Parents
  • 0
    Protection afforded by a B.S. 88-3 80kA H.R.C. fuse perhaps.

    https://www.youtube.com/watch?v=Ya_Zz1J0aYA


    If the S.P.D. shorts in use in extreme conditions its bits may fly about with the explosion due to the potentially large fault current within the device, so perhaps it is best to enclose it in a sturdy metal enclosure as well as having a H.R.C. fuse to protect the enclosure wiring.


    Z.
Reply
  • 0
    Protection afforded by a B.S. 88-3 80kA H.R.C. fuse perhaps.

    https://www.youtube.com/watch?v=Ya_Zz1J0aYA


    If the S.P.D. shorts in use in extreme conditions its bits may fly about with the explosion due to the potentially large fault current within the device, so perhaps it is best to enclose it in a sturdy metal enclosure as well as having a H.R.C. fuse to protect the enclosure wiring.


    Z.
Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines