Which of the following is a common inspection task for transformers during preventive maintenance?

A common inspection task for transformers during preventive maintenance involves conducting visual inspections and performing oil sampling. Visual inspections allow technicians to identify any signs of physical damage, leaks, corrosion, or other deteriorative conditions that could affect the transformer's operation and safety. This can include checking connections, insulation, and overall cleanliness.

Oil sampling is a critical aspect of transformer maintenance that helps in assessing the condition of the insulating and cooling oil. By analyzing oil samples, technicians can detect the presence of contaminants, moisture, or degradation products that may indicate internal issues such as overheating, oxidation, or electrical discharge. This proactive approach helps in extending the life of the transformer and ensuring its reliable operation.

In contrast, replacing all components is impractical and unnecessary for preventive maintenance, as not all transformer parts require replacement during each maintenance cycle. Upgrading transformer models and testing remote access systems may be relevant for modernization and operational efficiency but are not routine inspection tasks associated directly with preventive maintenance.