Generator Sizing KVA Power Calculator

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FAQ on Generator Power Consumption Calculator

How do I calculate the size of the generator I need?

Generators help provide power to buildings when there is a blackout or shortage of electric service. There are various types of generators, ranging from 800 to 500,000 watts. If you want to know the size of the generator, you must first know the generator power or the total wattage used. Each appliance has a specific running watt and an additional starting watt if it has a motor. So to calculate the total wattage of the appliances that come with an engine, you must find the sum of both the running watts and the additional starting watts of the appliance. You can just have the running wattage for the ones without a motor. Once you are done calculating the total wattage for each appliance, you can add the wattages of all the appliances that need the power to find out the right size of generator for your building.

How many KW's do I need in a generator?

Determining the proper size of the generator is essential and requires good knowledge of electricity and the load of the appliances that require power. It is also important for a successful installation. To calculate the kilowatts, you must first determine the starting amperage from each appliance's manufacturer's data plate. Then use the following formula to calculate the kilowatts.

Watts = Starting Amperage x Volts.

Once you know the watts, you can easily calculate kilowatts by multiplying the total watts by 1000. While choosing the output of the generator, always opt for ratings that are approximately 25% - 30% higher than the load. For example, if your total wattage is around 20 kilowatts, then choose a generator that is 25 kilowatts. The Generator Power Consumption Calculator that Sulekha offers helps you calculate the accurate size of your generator.

Why is it important to know the size of your generator?

It is important to buy the right sized generator to avoid many problems. You should be careful not to buy a generator that is too big for your needs or too small for your needs. An incorrectly sized generator produces unwanted noises and causes much damage to the electrical devices connected to it.

Disadvantages of large generators:
  • It causes severe damage to all the electrical systems.
  • It leads to unwanted operational costs.
  • It fails to produce efficient power.
  • Consumption of more fuel.
  • High maintenance costs.
Disadvantages of undersized generators:
  • It gets easily damaged due to excess power usage.
  • It gets overheated quickly.
  • There is not a sufficient or reliable power supply.
  • Failures in security systems.
  • There is a constant voltage drop and a slow current supply.

How do you calculate the KVA of a generator?

There are numerous ways to calculate the KVA of a generator based on the values you have.

  • When the voltage and current rating are known, then use the formula P(KVA) = VA/1000
  • When the voltage and output resistance is known, then use the formula P(KVA) = (V^2/R)/1000
  • When the power in watts and the power factor are known, then use the formula P(KVA) = P (watts)/pf

If you are still confused, use Sulekha's generator power consumption calculator to clear all your doubts.

How do I calculate generator fuel consumption?

The fuel consumption can be calculated by multiplying the energy consumed (kWh) by 0.27. Generally, the fuel consumption for a small diesel generator would be around 0.3 liters per kWh, and for a high-speed, diesel modern generator with over 900 KW, then the fuel consumption would be approximately 0.26 liters per kWh.

How much generator power do I need?

To calculate the generator power, you need to check the power rating in watts for each appliance using which you could easily calculate the total generator power requirement for your house. Instead of the power, if you step on the current rating, you could use Sulekha's generator power calculator to estimate the total generator power you will require for the house.

What is the running wattage of domestic appliances?

Domestic appliances Approximate starting wattage Approximate Running wattage
Bar fridge 550-600 150-200
Laptop computer 200-300 200-300
Refrigerator & freezer 1250-1300 500-550
Coffee maker 1100-1200 1100-1200
Portable fan 100-150 30-60
Tv 150-250 150-250
Desktop computer 250-300 250-300
Toaster 1100-1650 700-800
Household kettle 2100-2500 2100-2500

The wattages given here are the approximate values subject to change as per usage and circumstances.

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