Is there an "impedance voltage" across the transformer? So, what does this impedance voltage mean and what is it used for?
■ What is it?
Impedance voltage is a transformer parameter expressed as a percentage. The impedance voltage short-circuits the secondary winding of the transformer. Slowly increase the primary winding voltage.

■ How to test?
during the actual test. Testers can use professional testing equipment and follow the principle of impedance voltage. Short circuit voltage can be easily measured.
How to test with the help of instruments?
First, connect the wiring of the instrument according to the wiring method for measuring impedance voltage.
Secondly, the high-voltage connection instrument of the transformer should be reliably short-circuited on the secondary side.
Then, slowly pressurize the primary side of the transformer through the autotransformer.
Finally, increase the current. The voltage value until the current is equal to the rated current is the short-circuit voltage value we need.
It should be noted that the current value displayed in this instrument is the current value of the primary side.
Specifically, there are many things that need to be paid attention to during the test process, and professionals with high-voltage test verification are required to operate.
■ What's the use?
Impedance voltage is an important parameter of the transformer, which is related to many factors of the transformer, such as: capacity, copper loss, iron loss, etc.
Does impedance voltage matter? The impedance voltage is related to the stability of the power supply system, the power supply quality of the load, the safety and reliability of the parallel connection of the transformer, etc.
1. We can calculate the maximum short-circuit current that the transformer can withstand based on the impedance voltage, which is an important indicator for evaluating the transformer.
2. We can calculate the reactance of the transformer based on the impedance voltage. It is worth noting that the impedance voltage is a contradiction in practical applications.
Transformers with the same capacity have small impedance voltage and low cost, high efficiency and low price. The voltage drop and voltage change rate during operation are also small, and the voltage quality is easy to control and ensure.
Considering the short-circuit current limitation condition of the transformer, it is better to have a larger impedance voltage. To prevent electrical equipment (such as circuit breakers, isolation switches, cables, etc.) from being damaged by short-circuit current during operation.
Standardization of impedance voltage? It can also adapt to the parallel connection of transformers because transformers with different impedance voltages have different voltage fluctuations when loaded. When transformers with the same capacity but different impedance voltages are operated in parallel.
It will happen that the transformer with the smaller impedance voltage has been overloaded. The phenomenon that the transformer with larger impedance voltage is not yet fully loaded. Running two transformers in parallel is neither safe nor economical.
The above is an introduction to "short circuit impedance". Have you already formed a preliminary understanding of the "short-circuit impedance" parameters on the transformer nameplate?