
المشاركة الأصلية كتبت بواسطة hani51
Al salam Alaykum wa rahmatu allah
Attached high voltage distribution system design for disscussion concerning protections and distribution concept, the distance between transformers and HV switch gear varies between 15m to 100m .
All the professionals are invited to advice us with our appreciation .
Your fast replay is highly appreciated.
Thanks
Dear Brothers
I have the following reservation on the design
a- The LBS feeder ADDC Express feeder R rated 630A is too small
b- The 50N and 51N protection is not suitable for 100m distance, it must be replaced by 50G and 51G using core balance toroids to be able to detect internal faults in the xfmrs
c- The schematic doesn't show type of xfmrs used oil or dry. I suggest interconnection between the xfmr protection Buchholz, DGPT or PTC to be used depending on xfmr type
d-I don't see any interlocks on the bus-tie, interlocks must be used to prevent wrong operation.
e- I don't see on the schematics earthing switches. if earthing switches are used then special key-lock systems must be used
f- The CTs are too big for the xfmr sizes, this will prevent good metering and protection
g- What is the distance between the xfmrs and the LV switchgear, if it is longer than twenty meters then busways must be used because MV side will not provide
protection for faults on the LV side cables if the xfmrs are delta star
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