Oil switches are used for high voltage and large current circuits. They are specifically designed to handle the high electrical loads and provide reliable switching operations in such circuits. These switches are widely used in power systems and industrial applications where high voltage and large current levels are present.

Oil switches, also known as oil-filled switches, utilize a dielectric oil as an insulating medium to prevent arcing and ensure the safe interruption of high electrical currents. The oil used in these switches is typically mineral oil or synthetic oil, which has excellent electrical insulation properties.

Oil switches consist of a fixed contact and a movable contact that are immersed in the oil-filled chamber. When the switch is closed, the movable contact makes contact with the fixed contact, allowing the flow of current. On the other hand, when the switch is opened, the contacts separate, creating a gap between them and interrupting the current flow.

The key reasons for using oil switches in high voltage and large current circuits are as follows:

1. Arc Extinction: When the contacts separate during switching, an arc is formed due to the high electrical energy. The oil in the switch acts as an arc quenching medium, rapidly cooling and extinguishing the arc. This ensures safe interruption of the current flow and prevents damage to the switch and surrounding equipment.

2. Insulation: The oil provides excellent electrical insulation, preventing any leakage of current and ensuring the integrity of the switch. It also helps in maintaining the dielectric strength of the switch, allowing it to withstand high voltage levels.

3. Heat Dissipation: High current levels generate heat, and the oil in the switch helps in dissipating this heat effectively. It absorbs the heat generated during switching operations and prevents overheating of the contacts.

4. Contamination Control: The oil in the switch is carefully filtered and purified to remove any impurities or contaminants. This ensures the reliability and longevity of the switch, as contaminants can cause insulation breakdown or interfere with the switching operation.

In conclusion, oil switches are specifically designed for high voltage and large current circuits. They provide reliable switching operations, arc extinction, excellent insulation, effective heat dissipation, and contamination control. These switches are essential components in power systems and industrial applications, where safety, reliability, and efficient current interruption are crucial.