How to calculate mw of transformer?
Hospitals and industries have different output requirements in comparison to schools, colleges, and government buildings. The energy is received in the form of power.
Transformers receive power from the source. The amount of power required depends on the number of appliances in the concerned building and the time of their operation.
The needs vary depending on the type of business or purpose of building. So, the calculation of power requirements is the base of understanding the type of transformer needed.
Go on reading for assistance in mentioned calculations.
We can define a transformer load in two ways. Simply, it is the quantity of power that moves through the transformer. However, the transformer load can also be a regulator modifying its output.
The modifications can be in the form of power received by the appliances or the altered voltage flow to the receiving equipment.
So, during the transformer load calculation, you are calculating the current that can be transmitted. The full load capacity and safe load capacity are considered during the transformer load calculation.
Let’s understand the power ratings now!
The transformer load calculation is based on the output voltage and current of the electrical load of equipment to be used. The resultant will represent the power of the transformer with the unit in kilovolt amperes. To understand simply, 1 kVA can handle 100 Volts and 10 Amps of current.
How to calculate the apparent power ratings of equipment?
In transformer load calculation, the apparent power (kVA) or power (kW) of the equipment is based on its input needs which are voltage and current.
Ohm’s law can be used for calculation by the formula: V = IR, where V stands for Voltage, I stands for Current, and R stands for Resistance.
P = VI/1000. The obtained apparent power will be in kVA, which is to be divided by 0.8.
If the result is in decimal, values need to be rounded off, to calculate the power rating relating to the transformer power. (The division includes extra current required on turning the device on).
Single-phase and three-phase transformers
The mentioned calculations are aimed at single-phase transformers. If the transformer has power with a phase difference of 120 degrees, it is known as a three-phase transformer. The formula slightly varies in the case.
Thus, the transformer load calculation of a three-phase transformer will use the formula – P = VI√3/1000.
Other than multiplication with √3 or 1.732, all the steps remain the same including the division of the start-up current required by the device.
A few examples stating available sizes of transformers used commercially are 75 kVA, 112.5 kVA and 750 kVA. Typically, the range is between 3kVA to 1000 kVA.
The transformer load calculation can also be performed in terms of current ratings. The apparent power will be divided by the supply voltage followed by multiplication with 1000.
The end step will be multiplication with 25 (taking extra current on the start-up of the device into consideration).
We can also utilize the transformer load calculation method to find the voltage requirements of our equipment. For this, the formula will be (apparent power (kVA) × 1000) ÷ (current ratings).
So, now you have the safe voltage amount to flow from your equipment from the transformer load calculation formula.
The transformer is an important device required for the transmission and provision of power from the source. It provides power at the required voltage.
Transformer load calculation is the most significant and easiest method that can be used for the selection of a transformer. The method of calculation varies for single-phase transformers and three-phase transformers.
Transformer load calculation can be used for the selection of a transformer. The selection of a transformer also depends on other factors:
The transformer load calculation involves the usage of a safe amount of current load. This current load is 75% to 80% of the full current capacity of the transformer.
Division by 0.8 or multiplication with 1.25 in transformer load calculation indicates the inclusion of excess current required by the device when it is switched on.
Enter the VA rating and power factor the press the calculate button to get precious answer in Watts. Incase if the rating is mentioned in kVA or MVA then convert them into VA.
Transformers are always rated in VA or, kVA or MVA but sometime we may need to calculate the real power in Watt or kW or MW capacity of the transformer. That calculation is used to find out the rated real power of a transformer for using induction loads with variour power factor.
Transformer power P(W) in Watts is equal to rated power factor times of the rated VA rating S(VA). P(W) can be written as
P(W) = S(VA) x pf
Also, power can be calculated from kVA and MVA as below
P(W) = S(kVA) x pf x 1000
P(W) = S(MVA) x pf x 1000000
Transformer power P(kW) in kiloWatts (kW) is equal to the multiplication of power factor and rated kVA rating S(kVA) of the transformer.
P(kW) = S(kVA) x pf
Transformer real power P(MW) in Mega Watts is equal to the power factor times of the MVA rating of the transformer.
P(MVA) = S(MVA) x pf
Example:
A transformer name plate details are 15kW, 0.86 pf, 440V. Calculate the rated real power of the transformer
It is expressed in P = √3 x V x I where: V = Primary or Secondary Voltage. I = Primary or Secondary Current. √3 = 1.732.
