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, المشجعين, والضواغط, running watts are the steady-state power draw after the initial starting surge has passed.
What Are Starting Watts?
Starting watts (وتسمى أيضا زيادة واتس) 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
| نوع المحرك | Typical Surge Factor | مثال | 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 | ضواغط الهواء, table saws | Capacitor provides extra torque |
| Scroll Compressor (تكييف) | 2-3× running | Central AC units | Hard-start kit recommended |
| Rotary Compressor (ثلاجة) | 3-6× running | ثلاجات, المجمدات | Short duration surge |
| Submersible Pump | 3-5× running | Deep well pumps | Highest residential surge |
How to Calculate Total قدرة المولد
تحجيم المولدات formula: Total Running Watts + Largest Additional Starting Surge = Minimum Generator Starting Capacity
مثال: 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 (طفرة) سعة.
نصيحة هواكوان: Inverter مولدات handle starting surges differently — they can briefly exceed their rated output using بطارية-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.
