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  1. newelecteng

    Overvoltage During Earth Fault

    Dears We are experiencing an issue where, during an earth fault on our 33 kV outgoing feeder, the voltage measured by the ABB REF relay (Vo) on the incomer spikes to around 14 kV. This overvoltage is affecting our 0.4 kV system, which is fed by our ZNyn1 earthing transformer. Is this behavior...
  2. newelecteng

    YNd11 (earth fault at delta side)

    Hi all I have YNd11 transformer used as stepdown from 33kv(YN) to 11kv(d) to feed loads in 11 kv side -The question is If we have earth fault in 11kv systems how we can detect it. -is there will be reflection on star side of this earth fault. -Is it possible to have earth fault in this case...
  3. newelecteng

    Parallel transformer synchronization

    Hi all We have 2 identical step down 33/11kv power transformers fed from single source and feed radial lods with no generation at 11kv side. Does we need to have synchronisation between them in 11kv side Thanks in advance
  4. newelecteng

    Allen Bradley 1407CGCM showed up (CGCM fault) on HMI

    Hi all We are using Allen Bradley 1407CGCM for generators turbines . Before week ago an alarm showed up in HMI screen (CGCM1 fault). We try to reset but it does not cleared (still active). We got the same alarm before one month but it go when we reset. This alarm showed even though the unit...
  5. newelecteng

    1MW motor startup cause Turbine Generator to (trip on Differential) why!!

    Hello ALL, we install new (1Mw 3.3Kv motor DOL) connected to 3.3kv BB when when we try to switch it on. Sometimes especially after long motor shutdown it cause generator differential relay to Pickup and trip the generator. The 87G should be stable even if the mortar draw high stating current...
  6. newelecteng

    Is it possible for un-proper sync cause differential trip on Generator

    Hi all, When we try to synch 3.3kv/3.1mw generator to busbar throw CB. Some thing get wrong and the CB close without proper sync position then it trip with generator differential protection. After this trip we carry out full scale check on this unit and we don’t find any problem related 87G...
  7. newelecteng

    Solar turbine generator PMG lose

    Hi all We have solar gas turbine generator 3.1mw. We face yesterday PMG lose signal in HMI (the turbine reach it rated speed with 0 voltage and 0 excitation). We check PMG output from generator side it does not give any voltage. We check the PMG resistance it was 1.4omh (same as the other unit...
  8. newelecteng

    11kv voltage collapse during peak load at

    Hi all, we have 6 gas engines (0.4kv,1950kw each) connected to 11kv bus throw (0.4kv/11kv 3MVA transformers). this power station feeds residential loads in the countryside (air conditioners, water pumps, lighting, and workshops) throw 20km, 175mm2 OHL . I noticed the following during the...
  9. newelecteng

    Stuck Protection

    Hi all, what is stuck protection and how is it relate to BBP, Diff, CBF. Some engineers told me: stuck protection is like BBP but it just feed from Incomers CT and Bus section CT. Thanks.
  10. newelecteng

    50/51 51N/50N time grading on radial feeder

    Hi all, How to set protection (over current and earth fault) in terms of PICKUP and Time (first stage IDMT, second stage DT) on radial feeder shown on attached. Relay Type:Micom p127 Thanks in...
  11. newelecteng

    transformers neutral connection

    Hi all, We have 4 step up transformers(dYN) (0.4/11kv) they are connected to common utility busbar (11kv). Each transformer fed by 3 generators at (0.4kv) side. The 11kv side of transforms is (YN). Does we need to connect (every) transformer neutral to the ground or we just need to connect one...

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