1.SUBSTATION OVERVIEW -B. Prasad Chartered Engineer amieclub@gmail.com

2. TYPE OF SUBSTATION Classification based on voltage levels, e.g. : A.C. Substation : EHV, HV, MV, LV; HVDC Substation. Classification based on OutdoororIndoor: Outdoor substation is under open sky. Indoor substation is inside a building. Classification based on configuration, e.g. : Conventional air insulated outdoor substation or SF6 Gas Insulated Substation (GIS) Composite substations having combination of the above two 3. Classification based on application Step Up Substation : Associated with generating station as the generating voltage is low. Primary Grid Substation : Created at suitable load centre along Primary transmission lines. Secondary Substation : Along Secondary Transmission Line. Distribution Substation : Created where the transmission line voltage is Step Down to supply voltage. Bulksupply and industrial substation : Similar to distribution sub-station but created separately for each consumer. Mining Substation precaution for safety needed in the operation of electric supply. Mobile Substation: Temporary requirement 4. PROMARY/SECONDARY/DISTRIBUTION SUBSTATION Primary Substations receive power from EHV lines at 400KV, 220KV, 132KV and transform the voltage to 66KV, 33KV or 22KV (22KV is uncommon) to suit the local requirements in respect of both load and distance of ultimate consumers. These are also referred to EHV Substations. Secondary Substations receive power at 66/33KV which is stepped down usually to 11KV. Distribution Substations receive power at 11KV, 6.6 KV and step down to a volt suitable for LV distribution purposes, normally at 415 volts 5. SUBSTATION PARTSANDEQUIPMENTS OutdoorSwitchyard Incoming Lines Outgoing Lines Bus bar Transformers Bus post insulator & string insulators Substation Equipment such as Circuit- beakers, Isolators, Earthing Switches, Surge Arresters, CTs, VTs, Neutral Grounding equipment. 6. SUBSTATION PARTS .CONTD Station Earthing system comprising ground mat, risers, auxiliary mat, earthing strips, earthing spikes & earth electrodes. Overhead earth wire shielding against lightening strokes. Galvanised steel structures for towers, gantries, equipment supports. PLCC equipment including line trap, tuning unit, coupling capacitor, etc. Power cables Control cables for protection and control Roads, Railway track, cable trenches Station illumination system 7. SINGLE LINE DIAGRAM 8. Transformer part 9. Batteries forindustrial orsubstation applications Vented / Flooded Lead Acid batteries Sealed maintenance free batteries/Valve Regulated Lead Acid Nickel Cadmium (Ni-cd) batteries 10. Battery AH LOAD CURRENT 10A for 3 hrs. Cell voltage =12V DC CALCULATION , AH=10X3 CAPACITY =30/ (0.75X0.8)=50AH Discharge factor=0.7 Ageing factor =0.8 Drain capacity =C10 11. CHARGER Type of charger Input voltage output voltage Application Protection Metering Indication Alarms Auto operation 12. Clearance around an Indoorelectrical panel (NES 110.26) Description of Clearance Distance (min) Left to Right the minimum clearance 0.9 Meter (3 Ft) Distance between Panel and wall 1.0 Meter Distance between Panel and Ceiling 0.9 Meter Clear Height in front of Panel >480V 2.0 Meter Clear Height in front of Panel