Settings are illustrative starting points — confirm with a protection coordination study per IEC 60255 / IEEE 242.
📚 Calculation book
CALCULATION BOOK
2000 kVA - 10kV/0.4kV - single - illustrative
1. Load calculation
Standard: IEC 60076 - IEC 60364-5-52
Parameter
Formula
Value
Connected load
P = sum(kW)
1,800 kW
Demand factor
Kd
1
Demand power
Pd = P x Kd
1,800 kW
Power factor
cos(phi) before -> after
0.90 -> 0.95
Design apparent power
Sd = Pd / cos(phi)
1,895 kVA
Transformer loading
Sd / Srated
95%
2. Short-circuit calculation
Standard: IEC 60909
Parameter
Formula
Value
System impedance (pu)
Zs = S / Ssc
0.40% (on 2000 kVA base)
Transformer impedance
Zt = Z%
4%
Total impedance
Z = Zt + Zs
4.40%
LV prospective Isc
Isc = In / Z
65.6 kA
HV prospective Isc
Isc = Ssc / (sqrt(3) x V)
28.9 kA
Breaking check
Icu >= Isc
LV 80 kA (1.2x margin) PASS
3. Voltage drop
Standard: IEC 60364-5-52 Annex G
Parameter
Formula
Value
Main feeder
dU = sqrt(3) x I x L x R / V
240 mm2 - dU 1.00% @ 60 m
Limit
max 3%
within limit
Transformer volt. reg.
dU ~ loading x Z% x sin(phi)
1.2% at full load
4. Reactive power / harmonics
Standard: IEC 61921 (PFC) - IEEE 519 (harmonics)
Parameter
Formula
Value
Required compensation
Qc = Pd x (tan1 - tan2)
280 kvar
PFC bank
standard step
300 kvar
Detuned reactor
p = 6%
18.0 kvar @ 6% (anti-resonance)
5. Grounding
Standard: IEC 60364-5-54 earthing arrangements and protective conductors LV earthing target 10 ohm (TN systems); 4 ohm used as a conservative design target - target 4 ohm
Parameter
Formula
Value
Single rod resistance
R1 = rho/(2 x pi x L) x ln(4L/d)
39.6 ohm
Rods required
n = R1 / (target x 0.8)
13 rod(s) <= 4 ohm
Rod spec
dia x length
20 mm x 2.5 m
This calculation book is illustrative it consolidates the computed values with the referenced standards. A licensed engineer must verify and seal final design documents for construction.
🔧 Secondary schematic (control & signal)
🔩 Terminal strip (typical)
📏 Standard basis (依据标准)
Topic
Standard
Incoterms
Incoterms 2020 (ICC) — CIF · Cost, Insurance & Freight — seller pays ocean freight and insurance to destination; buyer bears import duty.
Transformers
IEC 60076 · GB/T 6451 — power transformers
Packaging & export
Equipment packed for ocean export per destination requirements
6.Total landed cost = $270,897 · estimated lead time 80 days (production ~40 d + freight 40 d)
📋 Design notes
Rates are typical ranges:Freight, insurance, duty, local labor and civil works percentages are illustrative industry-typical ranges, not quoted rates. Actual figures depend on vessel, container, HS code and destination — confirm with your freight forwarder and customs broker.
Currency & exchange rate:All amounts are quoted in USD (FOB Qingdao basis). Where a local-currency estimate is needed, apply the current USD exchange rate of the destination country at the time of quotation.
Duty basis:Import duty is calculated on the CIF value at the destination country’s MFN tariff for the relevant HS code (e.g. 8504.2x transformers). Duty is indicative only — confirm the exact HS code and rate with customs.
Incoterm CIF:Cost, Insurance & Freight — seller pays ocean freight and insurance to destination; buyer bears import duty. Under this term the seller's cost responsibility is reflected in the breakdown.
Equipment basis:Equipment FOB covers a 2000 kVA transformer + switchgear package from the catalogue. Civil works, substation building and electrical installation are separate (included only in turnkey scope).
Not an offer:This is a budget estimate for planning, not a binding quotation. Request a formal quotation for a firm price and delivery schedule.
What is the difference between FOB and landed cost?
FOB (Free On Board) is the price at the port of export, covering the goods plus loading. Landed cost adds ocean freight, insurance, import duty and inland transport to the destination. A $43,000 FOB Transformer might land at $48,000-55,000 after freight (2-5%), duty (5-15%) and handling. The calculator budgets FOB through landed.
What Incoterms should I use for transformer exports?
Common choices: EXW (buyer takes all cost/risk from factory), FOB (seller loads at export port), CIF (seller covers freight and insurance to destination port), DAP/DDP (seller delivers to destination). CIF or FOB is standard for heavy equipment. The calculator follows Incoterms 2020 and lets you budget each term.
How much is ocean freight for a transformer?
Ocean freight for a 40-ton transformer typically runs 2-6% of the equipment value for a full container or breakbulk shipment, but heavy-lift or out-of-gauge cargo can reach 8-15%. Distance and route matter more than weight within reason. The calculator applies a freight percentage and estimates the landed figure.
What import duty applies to power transformers?
Import duty on power transformers varies by country, typically 0-15% under HS code 8504. Some countries grant duty exemption for renewable-energy or infrastructure projects. Always confirm the destination HS code and tariff. The calculator applies your duty rate to compute the landed cost.
How long is the lead time for a transformer package?
Standard distribution transformers ship in 4-8 weeks; custom MV units and box substations take 8-16 weeks; large power transformers 16-40 weeks. Ocean freight adds 3-8 weeks depending on route. The calculator includes a lead-time estimate for planning.