Final answer:
You can distinguish the primary winding from the secondary winding in a step-up transformer by using the transformer equation, which relates the ratio of turns and the resulting voltage transformation.
Step-by-step explanation:
When determining how to distinguish the primary winding from the secondary winding in a step-up transformer, it's essential to understand the transformer equation. This equation states that the ratio of the secondary to primary voltages is equal to the ratio of the number of loops or turns in their coils. To identify the primary winding when only one bushing is present and the primary coil rating follows the system voltage, it must be connected in such a way that the transformer operates safely and effectively according to its design.
For a step-up transformer, the primary winding will have fewer turns than the secondary winding since it is designed to increase voltage from the primary to the secondary side. Moreover, transformers are grounded in specific ways depending on their design and the electrical codes applicable in the installation area.