The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

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 21 replies
  • Subscribers 31 subscribers
  • Views 2478 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

Schneider NSX micrologic trip units

Former Community Member
Former Community Member
Had a callout to a block of flats last night where one of these devices (250A) had tripped. Cause seems to be a fault on a lift, as its own 100A downstream device also tripped, so obviously not set correctly for discrimination. Problem is that after restoring the 250A device it now trips on a very small load, literally a couple of amps per phase. Wondered if anyone has seen this before? has the trip unit been destroyed by the fault or has its electronics got into a pickle?


As it was night time there was not enough load to even light the micrologic display. As a temp clear I managed to move the circuit onto an unused 100A device in the panel but for 13 flats and the communals dont know how long ill get away with that.


PS can the trip units be replaced safely on these units without isolating the upstream device, this would be a 1600A ACB feeding a very large development.


Thanks in advance


Tom
Parents
  • Former Community Member
    0 Former Community Member
    Have already read that whole document, the bit on page 13 says easy and safe replacement but not whether you can do it with the incoming terminals live. TBH i am 99% sure this would be safe to do, Schneider would have to say not recommended as the physical case could be damaged or fall apart while being worked on, plus of course EAWR. I have had the benefit of removing the front cover and having a poke round with a voltstick, I cant even get it light near the top live endof the breaker.


    The 24v power supply would be very useful, the battery one is about £180 though and I would imagine the leads to use your own PSU would be a bit pricey from schneider. Thinking a couple of old school 3kw electric heaters probably cheaper?. They seem to work at a bit less than 20%, the 400's light up at about 60A.
Reply
  • Former Community Member
    0 Former Community Member
    Have already read that whole document, the bit on page 13 says easy and safe replacement but not whether you can do it with the incoming terminals live. TBH i am 99% sure this would be safe to do, Schneider would have to say not recommended as the physical case could be damaged or fall apart while being worked on, plus of course EAWR. I have had the benefit of removing the front cover and having a poke round with a voltstick, I cant even get it light near the top live endof the breaker.


    The 24v power supply would be very useful, the battery one is about £180 though and I would imagine the leads to use your own PSU would be a bit pricey from schneider. Thinking a couple of old school 3kw electric heaters probably cheaper?. They seem to work at a bit less than 20%, the 400's light up at about 60A.
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