What is meant by primary voltage in an electric distribution system?

Primary voltage in an electric distribution system refers to the electric potential that exists above a certain designated level, typically found upstream of a transformer in the distribution network. This voltage level is crucial because it represents the high-voltage electricity that is transmitted from substations and fed into the grid before it is stepped down to lower, more usable voltages for consumer use.

The primary voltage is essential for efficient transmission over long distances, as higher voltage reduces current flow, which in turn decreases resistive losses in the transmission lines. This level of voltage is typically designed to be safe and manageable for distribution purposes, ensuring that the electricity can be effectively transformed to lower voltages for residential or commercial applications.

In contrast, the other options deal with different contexts of voltage within an electric distribution system. The concept of electric potential below a designated level relates to lower voltage systems, while voltage measured at the point of consumer supply relates to the lower voltage provided for end-use. Lastly, voltage used in the secondary distribution lines typically pertains to the stepped-down voltages that directly supply consumers. Thus, understanding that primary voltage specifically refers to the higher voltage levels upstream of transformers helps clarify its critical role in the overall electric distribution system.