Working Voltage Explained: Definition, Importance, and Impact on Power Transmission

Working Voltage

The term "working voltage" refers to the maximum voltage that a device can withstand without sustaining damage or burning out, while ensuring the reliability, safety, and proper operation of both the device and associated circuits.

For long-distance power transmission, the use of high voltage is advantageous. In AC systems, maintaining a load power factor as close to unity as possible is also economically necessary. Practically, heavy currents are more challenging to handle than high voltages.

Higher transmission voltages can yield significant savings in conductor material costs. However, while employing extra-high voltages (EHV) reduces conductor material expenses, it increases the cost of insulating conductors—whether overhead or underground.

Adopting high voltages requires increasing the electrical clearances between conductors to prevent electrical discharge, which makes mechanical support structures more complex and costly.

Other issues associated with higher working voltages include enhanced insulation requirements for equipment, corona effects, and interference with radio and television signals. Notably, the insulation costs for transformers, switchgear, and other terminal equipment rise drastically. These problems—corona and radio interference—become particularly severe at extra-high working voltages. Additionally, the working voltage should account for future load growth.

In summary, higher voltages correspond to higher line costs. The voltage level of a system is thus determined by two key factors:

• The amount of power to be transmitted

• The length of the transmission line.