kVA and kW
Generator kVA to kW Explained
kVA is apparent power. kW is real, usable power. They are related by power factor: kW = kVA × power factor. Generators are often rated in kVA because the alternator has to supply current, not only the kilowatts the load consumes. Do not assume every set uses the same power factor. Read the plate.
- kVA is not kW
- 0.8 is only an example
- The plate beats the conversion
- Onsite across Gauteng
Apparent power and real power
Why are generators rated in kVA?
The alternator is limited by current and voltage, which is what kVA describes. The kilowatts you can use depend on the power factor of the load. A heater is different from a motor. That is why a conversion done with the wrong power factor sizes the set incorrectly.
A common example on standby sets is a power factor of 0.8. At that example only, 100 kVA × 0.8 = 80 kW. If the plate shows a different power factor, use the plate. The table further down is labelled as an example at 0.8. It is not a claim that your generator is 0.8.
Three-phase sets add balance across the phases. Motor starting current can be several times the running kilowatts. Sizing from a kW total on a spreadsheet, without the power factor, the phase and the starting load, is how a set looks large enough and still trips.
Using the numbers
Power factor, motors and phase
Why power factor matters
Power factor is the share of apparent power that becomes real power. Change the factor and the kW result changes. One conversion does not fit every site.
Three-phase considerations
A three-phase rating is for a three-phase system. Unbalanced single-phase loads on that set do not get to use the full kVA. Phase is a separate guide.
Motor starting loads
The running kW of a motor is not the current it draws as it starts. A set can be inside its kW rating and still bog down or trip on starting.
Why sizing is not only kW
Voltage, frequency, phase, power factor and starting current all sit beside kilowatts. The sizes page is where those are applied to a booking.
Example at 0.8 power factor
Arithmetic only, using kW = kVA × 0.8. Use these figures solely when the data plate power factor is 0.8. Otherwise use the kW printed on the plate.
| kVA on the example | kW at 0.8 power factor |
|---|---|
| 5 kVA | 4 kW |
| 10 kVA | 8 kW |
| 20 kVA | 16 kW |
| 30 kVA | 24 kW |
| 50 kVA | 40 kW |
| 100 kVA | 80 kW |
| 150 kVA | 120 kW |
| 200 kVA | 160 kW |
| 250 kVA | 200 kW |
| 500 kVA | 400 kW |
| 750 kVA | 600 kW |
| 1000 kVA | 800 kW |
5 kVA
4 kW
10 kVA
8 kW
20 kVA
16 kW
30 kVA
24 kW
50 kVA
40 kW
100 kVA
80 kW
150 kVA
120 kW
200 kVA
160 kW
250 kVA
200 kW
500 kVA
400 kW
750 kVA
600 kW
1000 kVA
800 kW
Related Pages
Sizes, phase and the data plate
- Generator SizeskVA bands used for bookings
- Single-Phase vs Three-PhaseHow the supply is arranged
- Data Plate GuideWhere kVA and kW are printed
- Load Bank TestingProve output under a real load
- Fuel ConsumptionLitres per hour against the real load
- Generator InstallationSizing a new standby set
- Commercial Generator RepairsBusiness loads and larger sets
Google reviews of ProService Generator Repairs
Google Review
Cummins engines require absolute precision, and their mechanics delivered exactly that during our 500kVA service, using genuine filters and providing a comprehensive diagnostic engine report.
Google Review
Baudouin engines are heavy-duty beasts, and this team services our 1000kVA unit perfectly, resolving a persistent cooling issue that other contractors couldn't figure out.
Common Questions
Questions about kVA and kW
What is the difference between kVA and kW?
kVA is apparent power. kW is real power. kW = kVA × power factor.
Is 100 kVA the same as 100 kW?
No. At a power factor of 0.8, 100 kVA is 80 kW. That 0.8 is an example. Your plate may differ.
Why do generator plates show kVA?
Because the alternator’s limit is voltage and current. Usable kilowatts depend on the load’s power factor.
Can I size a generator from kW alone?
No. Power factor, phase and motor starting current change what the set must supply.
Does every generator have a 0.8 power factor?
No. 0.8 is a common example. Read the power factor on the data plate before converting.
How do three-phase loads affect the rating?
The rating assumes the load is shared across the phases. A heavy load on one phase can overload that phase inside the nameplate kVA.
Where do I see the real numbers for my set?
On the generator data plate: kVA, kW if printed, voltage, and power factor. The data-plate guide walks through those fields.
Will a conversion tell me if the set can run the building?
It converts units. It does not test the building. A load test is the check when capacity is the question.
Still unsure what the fault is? Call or WhatsApp 082 057 4605 for onsite diagnosis.
Service Areas
Onsite visits across Gauteng
Technicians travel to the generator. These are the main Gauteng areas. Suburb pages sit under each region.
What to send before we attend
ProService Generator Repairs confirms an onsite visit from these details. Send what you have. A missing model number does not stop the booking.
- Location
- The suburb or site, so the visit can be booked in the right area.
- Make and model
- The generator brand and model, if they are known.
- kVA
- The size printed on the data plate.
- Fuel type
- Diesel, petrol, LPG, natural gas, or dual-fuel.
- Controller model
- The module name on the panel, when it is visible.
- Fault or alarm
- What the set does, and any text on the screen.
- Photos
- The generator, the data plate, and the controller or alarm. Send these on WhatsApp.
Book a Visit
Send a photo of the rating plate
kVA, kW and power factor on the plate are more useful than a conversion done from memory.
- Call
- 082 057 4605
- Message us on WhatsApp