Recent content by ciy

gardengnome747, Thanks for your information. Kiribanda and veritas, Thanks for your opinion. I agree to select by Ics. It's safer selection. However, have any guide or practice to highlight how to select CB according to Icu/Ics? Please advise, if any. Thanks again.

Dear All, There is a question I wonder to know how select the breaker. It assumed already have the calculated fault current by SKM. Which do I select the Icu or Ics accordingly? For example, the said calculated value is 42kA @480V InitSymRMS 3P. IEC breaker rating Icu/Ics = 50kA/38kA @500V...

Dear Bill, thanks for your clue, I think I figure out.

Hi everyone, there is a question need your help. 33kV underground XLPE cable, 2000mm2, the length are 20kM. If we need to consider reactive compensation, how to size/calculate the capacity of shunt reactor? Are there any textbook or standard we can refer? Thanks all.

Usually, you need to develop two scenarios, one for Utility and the other one for Generator. Then find the worst case to print on label.

Maybe you in-service some capacitors in your system.

7anoter4 and electricpete, Thanks for your excellent opinion. I also think that triplen harmonic current flow under a loop condition. Again, please advise how to get the magnitude of neutral current under unbalance condition? Should include triplen harmonic and unbalance current? Regards,

Hi, I find an image in the website accidently about the harmonic issue. This image mark the direction of triple order harmonic. So, I curious and wonder to know their direction if lost the neutral line or add grounding wire. Please find the five(5) schematic as attached and advise these...

FreddyNurk and Bill, thanks for your reply. Bill, thanks for your excellent explanation.

Hi, In 3φ4W power system like 208/120V and 416/240V, G and N wire need to take care. There are 4 connection cases between G and N wire as attached. Please advise which one is practice connection and their pros and cons. Any guideline or article that I can refer to ? Thanks for your advice. Have...

Dear davidbeach and krisys, Thanks your reply.

Dear all, Thanks for your reply. Is there any guideline for reference? ciy

Hi, Please advise when undervoltage Relay (27) Shall be trip the CB or just alarm only? What is need to concern? Is there any criteria for following? Thanks. ciy

Thanks for your reply from Evergreen1231 and cranky108. The tertiary winding is also Wye connection. I wonder which damage curve of winding should be concerned? Secondary winding? Tertiary winding?

Dear all, There is a three-winding transformer rated: 345/13.8/6.9 kV transformer; 92/54.5/37.5 MVA The impedance percentage of PS/PT/ST is 16/13/1.9%. Please advise how to draw its damage curve? What is the difference between the 2 winding and 3 winding transformer? Thanks for your help in...