[EL] 問﹕How to Plan & Design Electricity Supply System for Building?

答﹕

Supply side:

1. Dual HV feeders from the supply grid for sensitive buildings;
2. Decentralize, if more than 3 Tx, multiple room, ensure Tx room & LV switch room free of water hazard; Transformer room & LV switch room closed to the load centre if possible to reduce copper loss;
   
   
   
   一般1500kVA一隻牛，但可特別申請2000kVA；一間房可放一至三隻牛。
3. Dual supplies and Interconnecting facilities, if multi-transformer installation, backup Tx capable to handle essential load from failure Tx, say 25%;
   Diverse supply routing, main electrical distribution circuits/risers separated into two electrical rooms/risers ;
4. Sufficient capacity reserve for various design considerations, future expansion, power harmonics from electronic ballast for lamps, VSD, IT equipment etc., say 20%;
   Spare switchgears/cable containment between the two electrical rooms/risers;
5. Vertical in-line of risers, avoid material wastage and lower the headroom;
6. Essential and non-essential switchboard seprate compartment;
   
7. CAT5 singal transmission limit
   

Click開就睇到兩隻牛互相backup electrical diagram

Secondary Backup Power Supply

1. Emergency Genset, may consider N+1 and sufficient capacity of fuel tank; https://elvissharing.blogspot.com/2020/03/el-fs-genset.html
2. Plug in point for mobile genset
3. UPS/EPS (香港好似叫Central Battery System CBS;
   
   Genset initial & operating cost最平，UPS最貴，切換最快；EPS切換慢過UPS但平過UPS;

Metering
Electricity kWh Meters --> 計電費用
Separate Check Meters --> Energy Aduit 用
另外，啲Fixed Telecommunication Network Services FTNS Operators, 唔同商戶、停車場等，都用獨立電錶計電。main circuit, sub main circuit, freeder circuit等都會掛。

Voltage Dip Compensator:

電壓忽然發生驟降，可以用舊Voltage Dip Compensator 解決，有Capacitor Type or Battery Type

個人感想﹕商業世界同政府Project都幾唔同，商業世界求Initial cost低，慳到錢先係王道；政府則求穩，無限備份，錢唔係重點。

(鳴謝﹕Raymond Cheng)