Transformer terminology — primary vs secondary: The primary winding of a transformer is the winding connected to the source, while the secondary is connected to the load. Assess the claim: “The primary winding is the side connected to the load.”

Introduction / Context:
Clear terminology prevents wiring errors. By definition, the primary winding is connected to the driving source; the secondary winding delivers power to the load. Some contexts label windings by function (input vs output) rather than voltage magnitude (step-up or step-down), but “primary-to-source” remains the standard convention.

Given Data / Assumptions:

• Conventional two-winding transformer.
• Primary: driven by a source; secondary: supplies a load.
• No unusual reconfiguration such as backfeeding unless explicitly stated.

Concept / Approach:
Primary and secondary roles are determined by which side is energized by the external source. Even if a transformer is used in reverse (backfed), the side currently connected to the source is, by function, acting as the primary for that use. Therefore, the claim that the primary is connected to the load is contrary to standard terminology.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets label windings as primary (input) and secondary (output). Installation instructions always treat the source-connected side as primary, avoiding confusion during wiring and protection sizing.

Why Other Options Are Wrong:

• Primary connected to load: Opposite to the standard definition.
• True only for step-down / depends on turns ratio / autotransformers: The naming is independent of ratio or construction; it is based on which side the source energizes.

Common Pitfalls:
Assuming “higher-voltage side” equals primary always; in backfeeding scenarios, roles can swap functionally — but the side tied to the source remains the primary for that setup.

Final Answer:
Incorrect — primary connects to the source