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Generator Sizing Formula:
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Generator sizing is the process of determining the appropriate generator capacity needed to power your equipment. Proper sizing ensures your generator can handle both the running (continuous) power requirements and the additional starting (surge) power needed when equipment first turns on.
The calculator uses the generator sizing formula:
Where:
Explanation: The equation sums both power requirements and converts watts to kilowatts (kW) by dividing by 1000.
Details: Correct generator sizing is crucial for reliable operation. An undersized generator may fail to start equipment or overload, while an oversized generator operates inefficiently and costs more to purchase and maintain.
Tips: Enter the running watts (continuous power requirement) and starting watts (initial surge requirement) for your equipment. Both values must be positive numbers.
Q1: How do I find running and starting watts for my equipment?
A: Check equipment nameplates, manuals, or manufacturer specifications. Starting watts are typically 1.5-3x running watts for motor-driven equipment.
Q2: Should I add a safety margin to the calculated size?
A: Yes, it's recommended to add 10-20% to the calculated kW to account for future additions and ensure reliable operation.
Q3: What's the difference between kW and kVA?
A: kW is real power, while kVA is apparent power (including reactive power). For resistive loads they're similar, but for motor loads, kVA will be higher.
Q4: How does altitude affect generator sizing?
A: At higher altitudes, generators lose about 3.5% of their power rating per 1000 feet above sea level due to thinner air.
Q5: Can I run multiple pieces of equipment simultaneously?
A: The calculator shows total capacity needed. For multiple devices, sum all running watts and use the highest starting watts (not all devices start simultaneously).