in the land of smiles...

A transfer switch allows safe switching between your mains supply (primary source) and your standby generator supply (secondary source) whilst ensuring both sources cannot be connected simultaneously. I'm sure you've figured out by now, that an automatic transfer switch carries out this operation automatically...

It does so by continually monitoring the incoming mains supply. If the voltage of the mains supply fails, is significantly reduced to create a brownout condition or surges outside of pre-determined parameters, it will immediately disconnect the mains supply and command the generator to start. Once the generator is producing a stable supply it will transfer the load to the generator. When a stable mains supply is restored it will carry out the reverse process, transferring the load back to the mains and shutting down the generator.

For many years automatic transfer switch panels relied on a collection of obtrusive phase failure relays, voltage balance relays and timers to achieve this process, but inovations in technology have given us digital controllers such as the ComAp InteliATS shown to the left of this paragraph. ComAp are a world leader in generator control, load transfer and synchronization technology and their products feature in all ATS, AMF and Synchronized panels we build.

To start and stop a generator, the ATS controller uses a remote start signal but does not control or monitor any generator functions or safety features unlike the AMF controller.

Using an ATS panel requires a generator to have the capacity to be started remotely and to monitor its own safety features (oil pressure, water temperature, coolant level). This is normally achieved through the addition of a secondary controller fitted on the generator itself. If the generator is not producing a stable supply (over/under voltage, over/under frequency or over current) the ATS controller will cut off the remote start signal and the generator will stop.

The controller manages the transfer of power by energizing and de-energizing contactors for the mains and generator supply which then passes through a circuit breaker (supply protection) at the distribution board/consumer unit location. . The contactors (pictured) are connected together using a mechanical interlock device and an electrical interlock, preventing both contactors from closing simultaneously.