Automatic Transfer Switching

By February 18, 2022ABB, All Whitepapers, Whitepaper


Automatic transfer switching

Over the past few years, service continuity in low voltage electrical installations has played an increasingly leading role. In actual fact, this requirement is a fundamental characteristic if economically and functionally efficient installations are to be created.

A system able to switch the supply from the main line to an emergency line reduces problems caused by faulty conditions in the public network to the minimum. These operations, commonly known as “automatic switching”, comprise sequences that automatically control the installation components (the circuit-breakers play a fundamental role) without interventions from the operator.

To guarantee that power is supplied to the loads, a fundamental requirement in an installation is to have a redundancy in supply sources type N+1, usually consisting of a transformer + emergency generator (or, as an alternative, a second transformer).


An installation with an automatic switching system:

  • prevents the industrial production process from being stopped
  • provides a power supply with high-quality voltage if the main network is out of service
  • reduces the effects caused by network faults on parts of the installation (voltage reduction leads to loss of stability in the rotating machines, a higher voltage drop, faults in the equipment, etc…)
  • achieves a good compromise amongst reliability, simplicity and cost-effectiveness
  • provides the maintenance staff and managing system with a power source able to supply the installation or part of it when the transformer is being serviced.