Where are tap changers typically located?

Tap changers are commonly found on the primary coil of a transformer because they are crucial for regulating voltage and maintaining system stability. By adjusting the number of turns in the winding, a tap changer can alter the transformer's voltage output to meet varying load demands and improve efficiency. This capability is vital in power distribution and transmission systems, where voltage levels can fluctuate.

In contrast, the other locations mentioned do not serve the same purpose. A tap changer located on the secondary coil would not effectively regulate input or output voltage in the context of load balancing at higher voltage levels, which is often managed at the primary side. Placement on the transformer casing is impractical as it doesn't provide the necessary electrical connection to manage voltage levels efficiently. Finally, positioning the tap changer at the load connection would hinder quick adjustments and could compromise the overall performance of the transformer. Therefore, positioning the tap changer on the primary coil is integral to the system's functionality.