Kích thước máy phát điện: How to Calculate Power Needs for Your Facility.

Choosing the right generator size is the single most important decision in your purchase. Get it wrong, and you face either frequent overloads (and shutdowns) or wasted capital on capacity you will never use. This guide gives you the exact calculation method engineers use—not guesswork.

Bước chân 1: Identify Your Critical Loads

List every device or system that must run during a power outage. These are your critical loads. For a typical commercial facility, that includes lighting, HVAC, bảo vệ, thiết bị CNTT, and process machinery.

Read the nameplate rating (in watts or amps) for each device. If only amps are available: Watts = Volts × Amps. For three-phase equipment: Watts = Volts × Amps × 1.732 × Power Factor.

Bước chân 2: Calculate Running vs. Starting Power

You need two numbers:

• Chạy kW: Sum of all loads’ chạy watt, divided by 1000.
• KVA khởi động: The largest motor’s starting kVA (typically 4-6x its running kVA) plus the sum of all others’ running kVA.

The generator must satisfy both numbers. Ví dụ: 30kW running total + 40kW starting surge = 50kW (62.5kVA) minimum generator.

Bước chân 3: Apply Safety Margins

Never size exactly to your load. Industry best practice adds:

• 25% future expansion margin — you will add equipment later
• 10% giảm độ cao if above 1000m / 3280ft
• 10% temperature derating for ambient above 40°C / 104° F

Final formula: Kích thước máy phát điện (kVA) = (Total Running kW × 1.25) -> 0.8

For a detailed walkthrough with downloadable calculator, see our Hướng dẫn định cỡ máy phát điện.

Các lỗi định cỡ phổ biến

• Bỏ qua dòng khởi động động cơ — motors draw 4-6x running current at startup
• Using nameplate kVA instead of kW — critical for engine loading calculations
• Forgetting power factor differences — UPS systems have harmonic loads that affect Kích thước máy phát điện
• Adding 100% redundancy unnecessarily — N+1 for critical, standalone for non-critical

Câu hỏi thường gặp">Câu hỏi thường gặp

How do I size a generator for motor loads?

Multiply the largest motor’s running kVA by 4-6 (depending on starting method) and add the sum of all other loads. For soft-start motors, use 2-3x. For VFD-driven motors, use 1.5x.

cái gì là 80% rule for generator sizing?

Máy phát điện should operate at 70-80% of rated capacity for optimal fuel efficiency. Sizing to 100% continuous load is not recommended for diesel engines as it accelerates carbon buildup.

Can I use a generator sizing calculator online?

Đúng. Many manufacturers provide free sizing tools. Tuy nhiên, always validate the results with a licensed electrical engineer for critical applications.

Related Resources

• Diesel Generator Fuel Consumption Guide
• Diesel Generator Price Guide
• Hướng dẫn định cỡ máy phát điện
• kW vs kVA: What’s the Difference
• 1000Máy phát điện kVA
• 100kVA Generator Specs