ATS and AMF are two terms often used interchangeably, even though they refer to different — if closely related — concepts. This confusion can lead to mistakes when specifying a backup power system.

ATS: Automatic Transfer Switch

An ATS is a mechanical/electrical device that automatically moves the power source from one source to another. Technically, an ATS is only responsible for switching — moving the load connection from the normal source (the grid) to an alternative source (the genset) and back.

An ATS doesn't "know" why a transfer is happening — it simply detects the loss of voltage from the main source and responds by transferring to the alternative source. Modern ATS units are equipped with solid-state controllers that can be configured for delay, retransfer, and various operating modes.

AMF: Automatic Mains Failure

An AMF is a more comprehensive system — it not only performs the transfer, but also manages the entire grid-failure scenario. The AMF detects the grid failure, commands the genset to start, waits for the genset to reach a ready condition (stable voltage and frequency), and only then transfers the load to the genset via the ATS.

When the grid is restored, the AMF detects the recovery, waits for grid stability (an anti-flicker timer), transfers the load back to the grid, then runs the genset's cool-down before shutting it down. AMF is the brain — ATS is the hand.

Key Technical Differences

• Standalone ATS: Only switches the connection. Requires the genset to already be running to function. Suitable for simple applications or redundancy.
• AMF panel: Integrates genset start/stop, genset condition monitoring, transfer switching, and protection. Suitable for fully automatic backup power.
• Response time: A modern ATS can transfer in under 1 second for a static transfer switch, but the genset needs to already be running. A full AMF sequence (including starting the genset) is typically 10–30 seconds.

When to Use Which?

ATS only: When the alternative source is always running (for example, two separate grid sources, or a genset that runs as prime power). Fast switching, simple system.

AMF: When the genset is on standby (off) and needs to start automatically when the grid fails. This is the most common configuration for building and industrial backup power.

AMF + Static Transfer Switch: For critical applications like data centers that need transfer times under 100ms. Expensive, but delivers near-perfect continuity.

Popular AMF Controllers

DSE (Deep Sea Electronics) 7xxx and 8xxx series are the most popular choices in the Indonesian market. ComAp InteliGen NT and InteliATS NT offer more advanced features including CAN bus and integrated remote monitoring. The DSE7320 is a reliable industrial workhorse at a competitive price.