Introduction: Why Generator Capacity Matters More Than You Think
Choosing the right diesel generator isn’t just about price or brand—it’s about capacity. If you buy too small, your operations stall. If you go too big, you waste money. In Bangladesh, where power cuts still disrupt homes and businesses, understanding diesel generator capacity—from 10kVA to 1000kVA—can mean the difference between smooth operations and financial headache.
What Does kVA Mean in a Generator?
Let’s get something straight: kVA stands for kilovolt-amps, not kilowatts. It’s a measure of apparent power, combining both real power (kW) and reactive power. You can think of kVA as the generator’s total capacity, while kW is what’s actually usable.
In Bangladesh, most generators are rated in kVA, because it’s a universal sizing standard for both single-phase and three-phase generators.
Key Conversion:
In general, 1 kVA = 0.8 kW (for a power factor of 0.8, which is standard in diesel generators).
Sizing Your Generator: It’s Not One-Size-Fits-All
1. For Homes and Small Offices (10kVA–30kVA)
If you’re running a typical household or a small office with lights, fans, computers, and an AC or two, a 10–15kVA single-phase generator usually does the job.
Use case examples:
- Rural homes in areas with daily load shedding
- Small pharmacies or clinics
- School computer labs
2. For Medium-Sized Businesses (40kVA–100kVA)
Restaurants, boutique hotels, medium-size supermarkets, and cold storages often need 40kVA to 100kVA three-phase generators. At this level, you need stable power for freezers, commercial kitchen gear, elevators, and HVAC systems.
3. For Factories and Industrial Units (125kVA–1000kVA)
Heavy machinery, textile mills, and production plants rely on large capacity diesel generators to keep the floor running. Here, the load is not just about lights—it’s compressors, motors, boilers, and automation systems.
A spinning mill may use a 500kVA generator, while a cement batching plant might need a 750kVA unit.
Single-Phase vs. Three-Phase: Which One Do You Need?
Single-Phase (Up to 20–25kVA)
- Supplies power via one alternating current (AC) waveform.
- Best for homes and small commercial loads.
- Lower installation cost, easier maintenance.
- Limited ability to handle large motors or sensitive industrial equipment.
Three-Phase (Above 25kVA)
- Distributes power through three separate AC waveforms, offset in phase.
- Suitable for industrial and commercial setups.
- Delivers constant power with fewer dips.
- Can power large machines, elevators, HVAC, and servers smoothly.
In Bangladesh, most commercial and industrial users opt for three-phase generators because utility connections are usually 3-phase, and their machinery demands it.
How to Calculate Your Load (Without Guesswork)
Getting the wrong capacity can kill your equipment—or drain your wallet. Here’s how to do it right:
Step 1: List Your Equipment
Include every electrical item: lights, fans, pumps, ACs, motors, computers, routers, compressors, etc.
Step 2: Find Total Wattage
Add up the wattage of all equipment. You can find this on the nameplate of the device or manual.
For motors and compressors, don’t forget to include starting wattage, which can be 2–3 times higher than running wattage.
Step 3: Convert to kW and Then to kVA
Let’s say your total load is 80,000W (or 80kW).
Now apply the power factor (commonly 0.8 for generators):
Required kVA = Total kW / Power Factor = 80 / 0.8 = 100 kVA
So, you need at least a 100kVA generator.
Step 4: Add 10–20% Buffer
Electrical loads often increase. Adding a buffer keeps your generator from running at 100% all the time, which shortens its lifespan.
Generator Capacity Guide for Bangladesh Users
| Generator Capacity | Suitable For | Phase Type | Common Uses |
|---|---|---|---|
| 10kVA – 15kVA | Homes, clinics | Single-phase | Fans, lights, fridge, TVs |
| 20kVA – 30kVA | Small offices | Single-phase | ACs, computers, CCTV |
| 40kVA – 60kVA | Restaurants, workshops | Three-phase | Freezers, lights, kitchen appliances |
| 75kVA – 100kVA | Cold storage, shops | Three-phase | Chillers, compressors |
| 125kVA – 250kVA | Small factories | Three-phase | Motors, lifts, welding |
| 300kVA – 500kVA | Textile or garment factories | Three-phase | Spinning, weaving, lighting, air compressors |
| 600kVA – 1000kVA | Heavy industries | Three-phase | Entire plant load, automated systems |
Fuel Consumption and Generator Capacity: What’s the Link?
Higher capacity = higher fuel usage. But it’s not linear. A 500kVA generator may burn 80–100 liters of diesel per hour at full load, while a 100kVA might use 20–25 liters.
That’s why proper sizing saves fuel. An oversized generator running at low load wastes diesel. A small one pushed to full load overheats and wears out quickly.
Avoid These Common Generator Sizing Mistakes
- Ignoring Starting Load: Especially for motors and ACs. Always include starting watts.
- Skipping Load Calculation: Estimating blindly leads to wrong capacity.
- Not Future-Proofing: Businesses grow. So does your power need.
- Overloading the Generator: Reduces efficiency and lifespan.
- Wrong Phase Selection: Using single-phase for a three-phase load creates imbalance.
Conclusion: Your Capacity is Your Lifeline
In Bangladesh’s challenging power environment, buying the right diesel generator capacity means you don’t suffer when the grid goes down. Whether you need a 10kVA backup for your home or a 1000kVA powerhouse for your textile mill, get your sizing right.
Don’t guess—calculate. Don’t overspend—analyze.
If you’re not sure what size you need, consult a diesel generator expert who understands local power conditions, load types, and fuel economics. That’s the smartest way to get uninterrupted power—without burning through your budget.
