At what Kvar rating does a capacitor bank require a vacuum or oil switch for sectionalizing?

A capacitor bank typically requires a vacuum or oil switch for sectionalizing at a rating of 180 Kvar. This is primarily due to the electrical characteristics and safety considerations associated with operating these systems at higher voltages and reactive power levels.

When the Kvar rating of a capacitor bank reaches around 180 Kvar, the operational currents become significant enough that the switching devices are subjected to wear and thermal stress. Vacuum or oil switches are preferred for this purpose because they can handle the high levels of current and provide better interrupting capacity than less robust designs like air-break switches. Additionally, these switches are designed to safely break the circuit without generating excessive arc energy, which is crucial for maintaining system integrity and protecting equipment from potential damage during switching operations.

Lower ratings, such as 100 Kvar or 150 Kvar, typically do not require such robust switching mechanisms as the current levels are more manageable and do not pose the same risks during operations. Hence, the need for a more reliable switching mechanism arises at the higher threshold of 180 Kvar, ensuring enhanced safety and operational reliability in the electrical distribution system.