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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
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  • 0
    Does it have an earth fault trip module  enabled ? - if so and there is an N-E fault in the lift or else where, it may be seeing your 1-2A load as an earth fault and flipping on that, much like an RCD will often trip on a part loaded circuit with an NE fault of modest resistance (as the current splits and some that should have come back via the neutral escapes to earth, and the trip sees the L-N imbalance when the percentage of the load escaping meets the trip setting)

    If you have photos, or the part numbers it may be possible to say more.

    It may also be worth talking to the



    Schneider UK Customer Care line   0370 608 8608 8am - 5pm Mon to Thurs and 8am - 4.30pm Fri. according to the website


    M.




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  • 0
    Does it have an earth fault trip module  enabled ? - if so and there is an N-E fault in the lift or else where, it may be seeing your 1-2A load as an earth fault and flipping on that, much like an RCD will often trip on a part loaded circuit with an NE fault of modest resistance (as the current splits and some that should have come back via the neutral escapes to earth, and the trip sees the L-N imbalance when the percentage of the load escaping meets the trip setting)

    If you have photos, or the part numbers it may be possible to say more.

    It may also be worth talking to the



    Schneider UK Customer Care line   0370 608 8608 8am - 5pm Mon to Thurs and 8am - 4.30pm Fri. according to the website


    M.




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