Bir su veya atık su pompa istasyonu için güç dağıtımını boyutlandırın — pompa yükleri, transformatör ve şalt cihazı seçimi, soft-starter veya VFD tercihi, ayrıca değişken hızlı ile sabit hızlı enerji karşılaştırması.
Pompa istasyonları su altyapısının temel yüklerindendir. Bu hesaplayıcı, pompa gücü, pompa sayısı ve eşzamanlılık faktöründen transformatörü boyutlandırır, gerilim düşümü kontrolü ile yol verme yöntemini (soft-starter veya VFD) seçer ve benzerlik yasalarını kullanarak VFD kontrolünün yıllık enerji tasarrufunu tahmin eder.
Worked Examples
Example 1 — 6 × 160 kW Pump Station (Soft Starter, VFD Comparison) · FOB $217,600
Water pumping power system · 10kV/0.4kV · Soft starter
Settings are illustrative starting points — confirm with a protection coordination study per IEC 60255 / IEEE 242.
📚 Calculation book
CALCULATION BOOK
1000 kVA - 10kV/0.4kV - single - illustrative
1. Load calculation
Standard: IEC 60076 - IEC 60364-5-52
Parameter
Formula
Value
Connected load
P = sum(kW)
960 kW
Demand factor
Kd
0.7
Demand power
Pd = P x Kd
672 kW
Power factor
cos(phi) before -> after
0.85 -> 0.95
Design apparent power
Sd = Pd / cos(phi)
707 kVA
Transformer loading
Sd / Srated
71%
2. Short-circuit calculation
Standard: IEC 60909
Parameter
Formula
Value
System impedance (pu)
Zs = S / Ssc
0.33% (on 1000 kVA base)
Transformer impedance
Zt = Z%
6%
Total impedance
Z = Zt + Zs
6.33%
LV prospective Isc
Isc = In / Z
22.8 kA
HV prospective Isc
Isc = Ssc / (sqrt(3) x V)
17.3 kA
Breaking check
Icu >= Isc
LV 25 kA (1.1x 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 1.17% @ 80 m
Limit
max 3%
within limit
Transformer volt. reg.
dU ~ loading x Z% x sin(phi)
1.3% at full load
4. Reactive power / harmonics
Standard: IEC 61921 (PFC) - IEEE 519 (harmonics)
Parameter
Formula
Value
Required compensation
Qc = Pd x (tan1 - tan2)
196 kvar
PFC bank
standard step
200 kvar
Detuned reactor
p = 6%
12.0 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.
Cable & grounding pricing:Cable conductors and grounding are priced from the confirmed cables-trays-grounding price reference (per-metre copper YJV; aluminium remains POA). The main copper busbar is POA — its length is project-specific.
Busway (high-current feeders):For LV feeders above ~2500 A, a busway (母线槽) trunking system is recommended instead of parallel cables.
Starting:Each 160 kW pump started Soft starter draws a 3.8% bus dip (within 15% limit).
VFD savings:At 70% average flow, VFD control saves ≈ 60% energy vs fixed-speed throttling (1,297,920 kWh/yr). Actual savings depend on the pump duty profile.
Static head correction:The affinity-law saving (P∝n³) assumes negligible static head. Where the pump lifts against a static head (elevation/tank pressure), the achievable saving is lower — the calculated figure is the ideal upper bound.
Pumps & valves:Pump units and control valves are quoted per project (POA) — this calculator sizes the electrical side (transformer, switchgear, starters/VFD).
Simultaneity:Not all pumps run together — demand factor 0.7 avoids oversizing the transformer.
Nasıl hesaplandı
Boyutlandırma nasıl yapılır
Talep P = pompa sayısı × kW × eşzamanlılık. Yol verme yöntemi, yol verme akımı kat sayısı kst'yi ve bunun sonucunda bara gerilim düşümünü belirler. VFD çalışmasında mil gücü benzerlik yasasına uyar: P ∝ (hız)³, dolayısıyla azaltılmış ortalama debide çalışmak, kısılmış enerjinin yaklaşık (1 − debi³) kadarını tasarruf ettirir.
Geçerli standartlar
Boyutlandırma referansları: GB 50265 (pompa istasyonu tasarımı), IEC 60034 (dönen makineler), IEC 61800 ve GB/T 25409 (ayarlanabilir hızlı sürücüler) ve GB 50052 (güç kaynağı tasarımı).
Sıkça sorulan sorular
Soft-starter or VFD — which is better for a pump station?
Soft starters suit constant-flow pumps where only the start is harsh; they cost 40-60% less than a VFD and have lower losses. VFDs pay off when flow varies (average flow below ~80% of rated) because pump power follows the affinity cube law — cutting speed 20% saves nearly 50% of energy. The calculator compares both and estimates payback on variable-speed operation.
How much energy can a VFD save on a pump?
Pump power varies with the cube of speed (affinity laws). Running at 80% speed uses about 51% of full-speed power; at 70% speed it is 34%. For a 160 kW pump running 4000 h/yr at 0.7 average flow, a VFD can save 40-50% energy versus throttling. The calculator quantifies the kWh and cost saving for your duty point.
What transformer size does a multi-pump station need?
Sum pump ratings, apply a simultaneity factor (0.6-0.8 for multiple pumps) and Power Factor (0.85-0.9), then select the next standard kVA. Six 160 kW pumps at 0.7 simultaneity and 0.88 pf need about 760 kVA, so select 800 kVA. Account for the largest pump starting; the calculator sizes the Transformer and Switchgear together.
What cable sizing rules apply to pump motor feeders?
Pump feeder cables are sized for ampacity (IEC 60364-5-52) and voltage drop, and to withstand the motor starting current. A 160 kW, 0.4 kV motor draws ~290 A full-load and ~5x on DOL start; the cable must carry the starting current briefly and keep steady-state drop under 5%. The calculator recommends the cross-section and checks the starting dip.
How do I compare fixed-speed vs variable-speed pump energy?
Fixed-speed pumps run at full speed and throttle flow (wasting head), while variable-speed pumps match speed to demand. For a duty point at 70% flow, variable speed cuts energy ~34%. The calculator takes annual operating hours, average flow and tariff to compute both energy costs and the simple payback of a VFD investment.
What protection does a pump motor need?
A pump motor needs overload (thermal), short-circuit, phase-loss and earth-fault protection, plus dry-run protection for submersible pumps. IEC 60947 and GB/T 14048 define the protection devices; motor starters integrate a contactor plus thermal relay. The calculator's BOM includes a motor soft-starter or VFD with integrated protection per pump rating.
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