How are isolated grounds usually connected in power supplies?

Isolated grounds in power supplies are typically connected to create a dedicated ground reference point that is separate from the general grounding system. These isolated grounds are often used in sensitive electronic and electrical equipment to minimize electromagnetic interference (EMI) and ensure a clean and stable ground reference for critical circuits. Here’s how isolated grounds are usually connected in power supplies:

1. Separate Grounding Conductor: In an isolated ground setup, a dedicated grounding conductor is run from the isolated ground terminal of the power supply. This conductor is typically insulated and of a different color or marked to indicate its isolated ground status. It is routed separately from the general grounding conductors.
2. Isolated Ground Bar: The isolated grounding conductor is connected to an isolated ground bar or bus within the equipment or at a specific location in the facility’s electrical distribution system. This bar is isolated from the building’s primary ground system and is only connected to the isolated ground conductors.
3. Isolation from Other Grounds: The isolated ground bar is intentionally kept separate from the building’s primary grounding system to avoid any ground loops or interference. Ground loops can introduce unwanted electrical noise into sensitive equipment.
4. Use of Isolated Receptacles: In some installations, isolated grounding conductors are connected to specific isolated ground receptacles. These receptacles have a dedicated ground pin for the isolated ground conductor. Equipment that requires a clean ground reference can be plugged into these receptacles.
5. Testing and Verification: It’s crucial to test and verify the integrity of the isolated ground system to ensure it remains separate from the primary grounding system. This involves conducting resistance and continuity tests and may require periodic inspections.
6. Labeling and Documentation: All components of the isolated ground system, including conductors, receptacles, and the isolated ground bar, should be labeled and documented clearly to distinguish them from the general grounding system.

Isolated grounds are commonly used in environments where electrical noise, such as EMI or radio frequency interference (RFI), can negatively affect sensitive electronic equipment. By creating a dedicated ground reference, isolated grounds help maintain signal integrity and reduce the risk of interference, ensuring the reliable operation of critical systems.