Conductive Level Switches

Principle

Conductive level switches use the liquid in a vessel to complete an electrical circuit. Multiple electrodes (one for each switch point) extend into the vessel. As the liquid level rises, it bridges the gap between electrodes, completing the circuit and triggering the relays.

Advantages

• No moving parts, making it suitable for liquids with suspended solids

Disadvantages

• Ineffective with solids
• Only works with conductive liquids (e.g., not suitable for fuel or oil)
• Not ideal for coating liquids like paints

Considerations

In metal tanks, only one electrode per switch point is needed since the tank itself acts as an electrode. For plastic or non-conductive tanks, an additional ‘source’ electrode is required.