Electrical Safety

Did you know?

A normal-standby transfer switch (or simply NS transfer switch) is an electrical device used in energy distribution systems to manage power redundancy between two energy sources. It is especially common in installations where continuous service is critical, such as hospitals, data centers, or sensitive industrial facilities.

Basic operation:

The NS transfer switch automatically or manually switches between:

• Normal source: usually the main power supply from the electrical grid.
• Backup source: an alternative source, such as a generator, uninterruptible power supply (UPS), or another backup power source.

Modes of operation:

• Normal mode: The load is powered by the normal source.
• Standby mode: In the event of a failure or outage of the normal source, the transfer switch automatically transfers power to the backup source to ensure continuous service.
• Return to normal: Once the normal source is restored and stabilized, the transfer switch can return power to the main source, usually with a delay to avoid any disruption.

Types of NS transfer switches:

• Manual: Require human intervention to perform the switch.
• Automatic: Ensure quick and autonomous transition between the two sources based on defined criteria (absence of voltage, voltage quality, etc.).

Main uses:

• Ensure continuous power supply in critical environments.
• Allow planned maintenance or testing of the normal source without power interruption.

Advantages:

• Increased security due to redundancy.
• Continuous power in case of failure.
• Flexibility to manage different energy sources.