- 2080 Chaitra · 8 marks
Substation site criteria and H-pole BOQ
Short answer
Site must be near load centre, accessible with firm ground and safe surroundings. A typical 11/0.4 kV 50 kVA H-pole substation BoQ includes transformer, two poles, platform channels, arresters, fuses, AB switch, insulators, conductors, LT distribution box, cables, earthing sets, stay set, danger plate, concrete foundation and labour.
Explain about site evaluation criteria of Substation. Also, prepare a Bill of Quantity of 11/0.4kV 50 kVA H-Pole Distribution Substation.
Site evaluation criteria for a substation
- Near the load centre: reduces LT cable length, voltage drop, losses and copper cost.
- Access to the HT line: close to the 11 kV feeder route so the HT tap is short.
- Accessibility: road access for transporting the transformer and for maintenance and fire-fighting vehicles.
- Ground conditions: firm, level, non-flooding land; low soil resistivity for good earthing.
- Safety: away from fuel stores, chemicals, explosive areas, schools and crowded places; enough clearance from buildings and trees.
- Space: enough area for the present equipment, future expansion, fencing and working clearance.
- Environment: free from dust, corrosive fumes and salt spray (otherwise choose indoor type); good natural ventilation.
- Cost and legal issues: land cost, right-of-way, approval of the utility and local bodies.
- Aesthetics and noise: transformer noise and appearance in residential surroundings.
Bill of quantities: 11/0.4 kV, 50 kVA H-pole substation (typical)
| S.N. | Item | Unit | Qty |
|---|---|---|---|
| 1 | Distribution transformer 50 kVA, 11/0.4 kV, Dyn11, ONAN | No. | 1 |
| 2 | PSC / steel tubular pole, 11 m | No. | 2 |
| 3 | MS channel (100 × 50 mm) for transformer platform and cross-arms | Set | 1 |
| 4 | 11 kV lightning arrester, 9 kV, 5 kA | No. | 3 |
| 5 | 11 kV drop-out fuse unit with fuse links | Set | 3 |
| 6 | 11 kV AB switch, gang operated, 200 A | Set | 1 |
| 7 | 11 kV pin insulators with pins | No. | 6 |
| 8 | 11 kV disc insulators with hardware | Set | 3–6 |
| 9 | HT jumper conductor (ACSR Dog/Rabbit) | m | 30 |
| 10 | LT distribution box with MCCB 100 A (or fuse units), busbars | No. | 1 |
| 11 | LT cable 1.1 kV, 3½ core 35 mm² Al XLPE (transformer to LT box) | m | 15 |
| 12 | LT shackle / spool insulators | No. | 8 |
| 13 | Earthing sets (pipe/plate electrode, GI strip/wire, chamber) | Set | 3 |
| 14 | GI earth wire 8 SWG | kg | 20 |
| 15 | Stay set complete with stay wire and insulator | Set | 2 |
| 16 | Danger plate and anti-climbing device | Set | 2 |
| 17 | Bolts, nuts, clamps, lugs, connectors | Lot | 1 |
| 18 | Concrete for pole foundation | m³ | 1.5 |
| 19 | Labour, transport, testing and commissioning | Job | 1 |
Three separate earths are provided: one for the transformer neutral, one for the transformer body and metal parts, and one for the lightning arresters. Quantities are typical and vary with the utility's standard drawing.
✓ Answer checked by Claude Opus 5.5 (high effort)
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