230 VAC Autotransformers
What is an autotransformer?
An autotransformer features a single voltage winding shared between both sides. This sole winding is "tapped" at various points along its length to provide a percentage of the primary voltage supply to the secondary load. Unlike a conventional double-wound transformer, the autotransformers have a magnetic core and only one winding common to both primary and secondary circuits, establishing both electrical and magnetic linkage. The significant advantage of this transformer design is its cost-effectiveness for the same VA rating.
An autotransformer features a single voltage winding shared between both sides. This sole winding is "tapped" at various points along its length to provide a percentage of the primary voltage supply to the secondary load. Unlike a conventional double-wound transformer, the autotransformers have a magnetic core and only one winding common to both primary and secondary circuits, establishing both electrical and magnetic linkage. The significant advantage of this transformer design is its cost-effectiveness for the same VA rating.
The part of the winding designated as the primary is linked to the AC power source, with the secondary being a portion of this primary winding. An autotransformer allows for voltage adjustment by reversing connections, enabling it to step down. When the primary constitutes the entire winding and is connected to a supply, and the secondary circuit is linked across only a section of the winding, the secondary voltage is effectively "stepped down".
The operational principle aligns with that of a conventional transformer, maintaining the same relationship between input and output voltages, input and output currents, and the ratio of turns between the primary and secondary windings.
The primary and secondary winding currents flow in opposite directions, resulting in the total current through the common winding being the difference between the low-voltage winding current and the high-voltage winding current.
Step-down autotransformer
If an alternating voltage is applied to the input points L and N, and the output voltage is measured at the output, a lower voltage is obtained. The supply voltage is 230 VAC and there are multiple tapping points. The possible output voltages available for this product group are: 80, 100, 120, 150, 170, 190 and 230 VAC.
Is an autotransformer suitable for my application?
Autotransformers are often employed as a cost-effective solution for adjusting supply voltage for particular load requirements, provided that isolation from the supply line is not necessary.
Autotransformers are commonly used for initiating the startup of induction motors, regulating the voltage in transmission lines and transforming voltages when the ratio between the primary and secondary is approximately unity. This adaptability makes autotransformers valuable across a range of situations, contributing to their widespread use in diverse applications.
Autotransformers prove to be optimal for adjusting voltage in commercial and industrial machinery. They offer a solution for delivering the required voltage to motors, compressors and other industrial equipment that necessitates stepping down from the building service voltage. Their compact design, typically half the size of a standard two-winding transformer, facilitates the installation process. What is more, Sentera’s ATR-1 series features a mounting bracket and a screw terminal block connection further simplifying the installation process. Also, two identical autotransformers can be connected to provide three-phase motor control for 230 VAC motors.
Our autotransformers feature a special impregnation, because even though the operated motor runs very silently, the autotransformer may produce some noise. Sentera’s special coating reduces this to the minimum level.
Sentera maintains an exclusive production line dedicated to autotransformers, underscoring our commitment to ensuring the highest standards of quality. Our autotransformers are also incorporated in our transformer-based fan speed controllers.