Understanding the difference between running watts and starting watts is the single most important concept for correctly sizing a generator. Confuse the two, and your generator will shut down the moment a motor-driven appliance turns on — or you’ll buy a generator far larger than you need.
What Are Running Watts?
Running watts (also called rated watts or continuous watts) are the power an appliance needs to keep operating after it’s already running. For resistive loads like heaters and incandescent lights, running watts equal the nameplate rating. For motor-driven loads like pumps, navijača, i kompresori, running watts are the steady-state power draw after the initial starting surge has passed.
What Are Starting Watts?
Starting watts (nazivaju se i udarni vati) are the brief burst of extra power that electric motors need to overcome inertia and begin rotating. This surge typically lasts only 1-3 seconds but can be 2-5 times the running wattage. Starting watts are caused by the motor’s locked-rotor current — the high current drawn before the rotor begins spinning and generating back-EMF.
Surge Factors by Motor Type
| Vrsta motora | Typical Surge Factor | Primjer | Starting Strategy |
|---|---|---|---|
| PSC (Permanent Split Capacitor) | 2-3× running | Furnace fans, small blowers | Standard startup |
| Split-Phase | 3-5× running | Well pumps, shop tools | May need soft starter |
| Capacitor Start / Induction Run | 3-4× running | Air compressors, table saws | Capacitor provides extra torque |
| Scroll Compressor (AC) | 2-3× running | Central AC units | Hard-start kit recommended |
| Rotary Compressor (frižider) | 3-6× running | Refrigerators, zamrzivači | Short duration surge |
| Submersible Pump | 3-5× running | Deep well pumps | Highest residential surge |
How to Calculate Total Kapacitet generatora
Dimenzioniranje generatora formula: Total Running Watts + Largest Additional Starting Surge = Minimum Generator Starting Capacity
Primjer: If your total running load is 4,000W and your well pump adds 3,500W of starting surge beyond its running watts, you need a generator rated for at least 7,500W starting (val) kapacitet.
Huaquan savjet: Inverter Generatori handle starting surges differently — they can briefly exceed their rated output using baterija-assisted surge technology. A 2,200W inverter generator may deliver 2,500W surge for a few seconds, which is often enough to start a refrigerator. For industrial applications with large motor loads, Huaquan diesel generators provide robust starting surge capability up to 5× rated output.
