The ideal transformer calculator is an excellent choice if you need to quickly analyze the basic properties of your devices using the transformer equation. We use transformers to increase or decrease the voltage of an alternating current (AC) signal, and they are essential components of power grids and are widely used in electronic equipment.

Read on to find out what a transformer is, learn about the transformer formula, and check interesting facts, such as how much copper is in a transformer. If you're already familiar with transformers, visit our dipole calculator to explore another topic related to antennas and how they operate.

What does a transformer do?

A transformer is a device that transfers electrical energy from one circuit to another through the use of electromagnetic induction. It relies on the fact that electricity can be generated by moving a conductor through a magnetic field. Transformers are not only used to increase or decrease the voltage of an alternating current (AC) supply, but they can convert between single-phase and three-phase connections.

Without transformers, we would have to rely on direct current (DC), which is not as efficient or practical for our needs. Therefore, it is essential to know what an electrical transformer is and how to use the transformer formula if you're dealing with electrical circuits. Luckily, the transformer ratio calculator makes the required computations much easier!

Transformer equation

The transformer formula shows the relationship between the input voltage VpV_p, the output voltage VsV_s, the number of turns on the primary winding NpN_p, and the number of turns on the secondary winding NsN_s. The transformer equation is:

Vs=Vp×NsNpV_s = V_p \times \frac{N_s}{N_p}

If you look at the ideal transformer calculator, you can notice that it can also find the primary IpI_p and secondary IsI_s currents relationship, which is the following:

Is=Ip×NpNsI_s = I_p \times \frac{N_p}{N_s}

Notice the ratio between windings is reversed in the above two transformer equations.

After understanding what a transformer is, let's inspect the possibilities of our simple tool, which can:

  1. Find the increase of voltage: step-up transformer calculator.
  2. Find the decrease of voltage: step-down transformer calculator.
  3. Determine the number of windings: transformer winding calculator.
  4. Estimate the wattage change: transformer wattage calculator.

We'll take a closer look at all of them in the following sections.

Step-up transformer calculator

If you need to increase the voltage of an AC supply, you can use a step-up transformer. A step-up transformer increases the voltage of an AC supply by increasing the number of turns on the secondary winding relative to the number of turns on the primary winding.

So, to use our tool as a step-up transformer calculator, you need to input the number that follows the inequality Ns>NpN_s > N_p.

Step-down transformer calculator

If you need to decrease the voltage of an AC supply, you can use a step-down transformer. A step-down transformer decreases the voltage of an AC supply by decreasing the number of turns on the secondary winding relative to the number of turns on the primary winding.

So, to use our tool as a step-up transformer calculator, you need to input the number that follows the inequality Ns<NpN_s < N_p.

Transformer winding calculator

Our website offers the possibility of multi-directional calculations. It means that you can start by entering the values for voltages or currents. Then, if you input one of the windings (primary or secondary), the transformer turns ratio calculator will determine the missing one. It's that simple!

Transformer wattage calculator

The ideal transformer calculator can find the apparent power SS, which is conserved in the input and output. The formula we use is the following:

S=Ip×Vp=Is×IsS = I_p \times V_p = I_s \times I_s

Apart from apparent power, we also distinguish between real and reactive powers. We have written more about them in the three-phase calculator, providing everything you need to estimate each type of power for the three-phase connections.

How to test your transformer on your AC

You should now be able to answer the question: how does a transformer work?, if anybody asks you. Let's now switch to a more practical aspect and see how to test your transformer on your AC supply. To do it:

  1. You will need to measure the input and output voltage. You can use a multimeter to measure both values.
  2. The input voltage should be higher than the output voltage for a step-up transformer, and vice versa for a step-down transformer.
  3. Finally, measure the current through the primary and secondary windings with the multimeter. In the ideal case, they should correspond to values obtained with the ideal transformer calculator.

⚠️ In real transformers, power losses are present due to, for example, non-zero resistances of windings. Therefore, keep in mind the ideal transformer formula is just an approximation as well as our transformer turns ratio calculator's algorithm.

How much copper is in a transformer?

The amount of copper in a transformer depends on the size and capacity of the transformer. A small transformer may have only a few pounds (kilograms) of copper, while a large transformer can have upwards of 1000 pounds (500 kilograms) or more.

🔎 The majority of the weight in a transformer is actually iron, not copper.

How to wire a transformer

To wire a transformer, you will need two insulated wires: one for the primary winding and one for the secondary winding. The primary winding is usually made of thicker wire than the secondary winding because it usually carries more current. Here are the steps we would make to wire a transformer:

  1. Connect the primary winding to the AC power source.

  2. Connect the secondary winding to the load (the device that will use the transformed electrical energy).

  3. Make sure that the transformer is properly grounded. This will protect it from damage due to electrical surges.

  4. Test the transformer to make sure it is working properly.

Check the transformer sizing calculator to find the right transformer size for single or three-phase connections.

❗ When using a transformer, it is vital to keep in mind that the current in the secondary winding is proportional to the number of turns in the winding. This means that if you increase the number of turns, you will also increase the current. Too much current can damage the transformer or the load. Therefore, it is essential to choose the number of turns carefully.

Dominik Czernia, PhD candidate
Primary windings
Secondary windings
Primary voltage
Secondary voltage
Primary current
Secondary current
Apparent power
Apparent power
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