Energy transformers are very similar to transformers. They are used to transform the voltage on the line. The main difference lies in capacity, size, working magnetic density and compensation.
The purpose of the transformer to transform the voltage is to keep the electric energy, so the capacity is very large, and the purpose of the energy transformer to transform the voltage is mainly to supply power to the measuring instrument and the relay maintenance installation, to measure the voltage, power and electric energy of the line. Or it is used to maintain valuable equipment, motors and transformers in the line when the line fails, so the capacity of the energy transformer is small.
Energy-taking transformers are generally not used to provide power, but they do limit the rated power that can be connected. When there is no 120V power supply on site, energy transformers are often used to provide 120V temporary power for light maintenance equipment. In the switch room, the secondary side of the energy transformer can be used to drive the motor of the circuit breaker. In the regulator room, they can be used to identify the motor that drives the tap changer. The power range of the energy transformer is: 500VA and below for the low voltage energy transformer, 1~3kVA for the medium voltage transformer, and 3~5kA for the high voltage energy transformer. Since the rated power of the energy transformer is so small, their physical size is also very small.
The working magnetic density of the energy-taking transformer is far lower than the magnetic density of the transformer. This helps to reduce losses and prevent the transformer from overheating due to continuous overvoltage. If not clearly pointed out, energy transformers are usually designed to operate continuously at 110% of the rated voltage.