What are common types of isolators for LV/MV systems?

Isolators are categorized based on their mechanical design and application.

Common Types for Medium-Voltage (MV) Systems

These are typically open-air switches used in substations and are classified by how their moving arm operates:

• Vertical Break Isolator: The contact arm swings vertically into the air to create the isolating gap.
• Horizontal Break Isolator: These have three insulator posts per phase. The central post rotates, causing the two connected contact arms to open horizontally, creating two breaks in series. This is often called a "Double Break" or "Center Break" isolator.
• Pantograph Isolator: This uses a scissor-like mechanism. The moving arm retracts vertically to disconnect from an overhead busbar. This design is space-efficient.

Common Types for Low-Voltage (LV) Systems

In LV systems (like in commercial buildings, industries, and distribution panels), isolators are usually enclosed and more compact:

• Switch Disconnector (or Isolator Switch): This is a manually operated switch, often in a molded case. It's used as the main incoming switch in a panel to isolate the entire board for maintenance.
• Switch Fuse Disconnector / Fuse Switch Disconnector: This combines an isolator switch with fuses. It provides both circuit isolation and overcurrent protection via the fuses.
• Rotary Isolator: This type is operated by a rotary handle that clearly indicates the ON (closed) or OFF (open) position. They are commonly used to isolate individual machines or sections of a plant locally for maintenance. They are often housed in a durable, waterproof enclosure for outdoor or industrial use.