What power should a generator have of Grupel?

In times of need, generators convert mechanical energy into electrical energy, providing power. They are found in a variety of areas – both in the home and small businesses, as well as in industrial enterprises and large infrastructure projects. The main question that arises when choosing a generator is how much power it should have to meet the specific needs of the user.

Generator power

Generator power is measured in kilowatts (kW) or kilovolt-amperes (kVA). The main difference between these two units is that kilowatts measure real power while kilovolt-amperes measure apparent power. In power supplies where there are reactive loads (such as motors and transformers), apparent power is a more appropriate measure.

Real, reactive and apparent power

•Real Power (P): Measured in kilowatts (kW), it represents the actual power that does useful work in the system.

•Reactive power (Q): Measured in kilovar-amperes reactive (kVAR), it is required to create magnetic and electric fields in inductive and capacitive loads.

•Apparent power (S): Measured in kilovolt-amperes (kVA), it is the combined measure of real and reactive power given by the formula S = √(P² + Q²).

Factors affecting the choice of generator power

1. Type of cargo

One of the most important factors is the type of load that the generator will power. The loads can be:

•Resistive

• Inductive

• Capacitive

2. Starting current of electric motors

When starting, electric motors require significantly more current (starting current) than during normal operation. This inrush current can be 5-7 times the rated operating current.

3. Simultaneous operation of loads

When estimating the required generator power, consideration must also be given to how many loads will be operating at the same time.

4. Power factor

The power factor (cosφ) is a ratio between real and apparent power and ranges from 0 to 1. For example, with a power factor of 0.8, 10 kW of real power will require 12.5 kVA of apparent power.

5. Power reserve

The power reserve ensures the reliability and longevity of the generator. This reserve will help to cope with unexpected peaks in consumption and extend the life of the generator.

Calculation of the required power of the generator

Step 1: Calculate the total real power

We sum up the real power of all the loads that will be powered by the generator. This power must be measured in kilowatts (kW).

Example:

•Electric heater: 2 kW

• Lighting: 1.5 kW

•Computers: 1 kW

• Pump: 0.5 kW

•Total: 2 + 1.5 + 1 + 0.5 = 5 kW

Step 2: Calculate the apparent power

If the power factor of the loads is known, calculate the apparent power (S)

Example: If the power factor is 0.8, then:

S= 5kW:0.8 = 6.25kW

Step 3: Turn on the power reserve

It is recommended to add a power reserve, usually around 20%. This means multiplying the calculated apparent power by 1.2.

Example:

Reserve=6.25kVA×1.2=7.5kVA

Step 4: Select the generator

Select a generator whose rated power is equal to or slightly greater than the calculated required power with reserve included. In our example, a suitable generator would be about 7.5 kVA or more.

Choosing the right generator is extremely important to ensure a reliable power supply in various conditions. In order to make the right choice, many factors need to be considered.