[EL] 問﹕BEC / BEEO 2018 Electrical Installation 有啲乜要點？

答﹕

- Transformer efficiency: above 99%;

-Max. allowable copper loss for Main circuit, Feeder Circuit, Sub-main Circuit and Final Circuit;

• Main circuit (Tx to LV switch board) 0.5%;
• Feeder (LV switch board to equipment) 2.5%;
• Sub main circuit (LV switch board to local distrubution board) 矮過100m 1.5%; 高過100m 2.5%;
• Final circuit (Local distrubution board to equipment) 1%;

- Balancing of single phase loads: 3 phase 4 wire circuits 大過400A 而又有 1 phase load 的話，max unbalanced single phase loads 要少過10%;

- Min. allowable total Power Factor: 大過400A的話，要細過 0.85;

-Max. allowable total Harmonic Distortion: Harmonic Distortion in % of Designed Circuit Current 受限，Designed Circuit Current 越大，允許既% 越細 (同copper loss 一樣有公式計)；

- Metering and Monitoring in above circuit for energy aduit;

- Min allowable motor efficiency, 2-pole (單相) and 4-pole (三相) , motor rated output 越大，所以要既efficiency 越高；