Supply Voltage

This is the actual voltage provided by the power source to the electrical equipment or system.

It may fluctuate due to variations in the power grid, load conditions, or transmission losses.

Example: If a power grid provides 230V but fluctuates between 220V and 240V, the supply voltage is the real-time voltage delivered.

Nominal Voltage

This is the standard or rated voltage for which electrical devices, circuits, or systems are designed to operate.

It serves as a reference value and does not indicate the exact real-time voltage.

Example: In India, the nominal voltage for household appliances is 230V, meaning they are designed to work efficiently at or near this voltage.

Practical Impact
Electrical devices are built to handle slight variations in supply voltage around the nominal voltage.

Too much deviation from the nominal voltage can cause inefficiency, overheating, or damage to equipment.