500 kW School Power System Cost Breakdown (Q3 2026 China Supplier Pricing)
500 kW School Power System Cost Breakdown (Q3 2026 China Supplier Pricing) — itemized bill of materials and FOB pricing for a typical configuration.
Estimated total (FOB): $77,782 · 500 kVA transformer
Bill of materials
| Item | Specification | Qty | Price (USD) |
|---|---|---|---|
| HV incoming panel (KYN28A-12-630-315) | 630 A / 31.5 kA · vacuum | 2 | $4,896 |
| HV bus-tie panel (KYN28A-12-630-315) | 630 A / 31.5 kA · vacuum | 1 | $2,448 |
| Main transformer (each) (SCB13-500/10) | 500 kVA · Dry-Type · Copper · SCB13 | 2 | $21,861 |
| LV incoming panel (GGD-1000) | 1000 A busbar · In 722 A | 2 | $6,958 |
| LV bus-tie panel (GGD-1000) | 1000 A busbar | 1 | $3,479 |
| LV feeder panel (×2) (GGD-1000) | distributes 8 circuits | 2 | $6,958 |
| Cable branch box (LV) (DFW-0.4) | 1-in / 4-out · 0.4 kV · 630 A | 1 | $630 |
| Main feeder cable (TX→LV) (YJV 0.6/1kV 240 mm² ×2) | 2× 240 mm² Cu · ΔU 0.88% @ 60 m · $123.0/m | 2 | $14,760 |
| Feeder cable — Classroom 1 (×8) (YJV 16 mm²) | 16 mm² Cu · 76 A · ΔU 2.8% · $8.1/m | 8 | $3,888 |
| Branch trunk cable (LV → branch box 1) (YJV 150 mm²) | 150 mm² Cu · 304 A · ΔU 1.2% · $86.0/m | 1 | $5,160 |
| Main busbar (Cu) (Cu 63×6.3) | 63×6.3 · 900 A rating · ref $47/m | included | POA |
| Grounding electrode (Φ20mm × 2.5m rod) | R₁ 39.6 Ω → 13 rod(s) ≤ 4 Ω | 13 | $125 |
| Automatic transfer switch (ATS) (ATS 200 A (typ.)) | dual-source automatic transfer · GB 50052 load classification | 1 | $845 |
| Emergency power supply (EPS) (60 kW (typ.)) | emergency & fire lighting · GB 51309 | 1 | $5,775 |
Single-line diagram
How it was calculated
- School: total load 500 kW × design factor 0.8 = 400 kW (explicit coincidence factor — classroom/office occupancy diversity (0.8 coincidence factor))
- Redundancy N+1 → one spare unit, dual + tie
- Emergency level: standard → ATS, EPS (fire lighting),
- Loads: P=400 kW, PF 0.95, 8 circuits
- Demand: 400 × 0.9 = 360 kW
- PFC: Qc = 360 × (0.329 − 0.329) = 0 kVAR → 0 kVAR bank
- Transformer: S = 360 ÷ 0.95 = 378.9 kVA → 500 kVA standard
- Loading: 379 ÷ 500 = 76% (good range)
- Voltage regulation: 76% × 6% × sinφ ≈ 1.4% at full load
- HV: In 28.9 A, Isc 28.9 kA → KYN28A-12-630-315
- LV: In 722 A, Isc 11.8 kA (Xfmr Z 6% + system 0.1%) → GGD-1000, 2 feeder panel(s)
- Cable branch boxes: 1 × DFW-0.4 (1-in/4-out) for feeder grouping
What drives the cost
- Equipment — the transformer/switchgear/inverter is the largest single line item.
- Storage (where applicable) — batteries are the biggest swing factor.
- Copper & freight — copper-linked cabling and freight shift landed cost ±5–10%.
Frequently asked questions
What redundancy do hospitals require for power supply?
Hospitals are first-class important loads under GB 50052 and need two independent utility supplies plus an emergency source (diesel or EPS) that restores critical circuits in seconds. Life-support and operating rooms use 2N topology with UPS. The calculator models building type, redundancy (N+1/2N) and emergency level to size the full plant.
How is emergency power restored in public buildings?
An automatic transfer switch (ATS) detects supply loss and transfers to a standby diesel generator, which starts and reaches full load in 30-60 seconds. For millisecond-critical loads, a UPS bridges the gap. GB 50052 classifies the emergency level; the calculator sizes ATS, diesel/EPS and battery backup per the building's load class.
What is the typical load density of a hospital or stadium?
Hospitals run 60-120 W/m2 (up to 150 W/m2 with imaging), schools 30-60 W/m2, offices 50-80 W/m2, and stadiums 60-100 W/m2 plus floodlighting peaks. The calculator's 1500 kW default models a mid-size hospital; total demand sets the transformer and emergency ratings.
What transformer size does a 1500 kW hospital need?
A 1500 kW hospital at 0.95 pf needs about 1580 kVA, so select 2x800 kVA or 2x1000 kVA for N+1/2N redundancy. Hospitals often run two transformers with automatic bus-tie so either can carry critical load. The calculator selects standard IEC 60076 ratings and applies the chosen redundancy level.
What is an EPS and how does it differ from a UPS?
An emergency power supply (EPS) is an inverter-based backup for lighting and life-safety loads, transferring within 0.25-5 seconds — slower than a UPS (0-10 ms) but cheaper per kVA and built for motor and lighting duty. UPS serves electronics that cannot tolerate any interruption. The calculator selects EPS for emergency lighting and UPS for critical IT.
What power quality rules apply to public buildings?
Public buildings must limit harmonic distortion per IEEE 519 (5-8% THD at PCC) and maintain power factor above ~0.9 to avoid utility penalties. LED lighting and VFD HVAC drives inject harmonics, so detuned capacitors or APFs are common. The calculator checks pf and harmonic share and sizes compensation accordingly.
Size your own configuration
Run the calculator for your exact load and get a full BOM + FOB price.
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