What is the Automatic Transfer Switch for in a generator?

Some components can be added to a generator and really make a difference, because they optimize its operation, responding to more complex requirements. The automatic transfer switch is one of them, because, as the name implies, it is a component that allows the automatic switching of the energy source that feeds the load, transferring it, normally, between the mains and the generator.

The generator controller examines the grid and, when it fails to supply power, the generator starts. As soon as it is stabilized and prepared to supply power to the installation, the automatic transfer switch changes the power source, connecting the generator to the load.

When power is restored in the mains, this equipment is responsible for a new switching, connecting the load to it.

Grupel's load transfer frames can be distinguished according to the level of insulation:

  • Class 1 switchs are made of galvanized steel sheet, and protection against electric shock is not guaranteed only by the main insulation. This isolation is done by connecting all the conductive parts to the same protection terminal that will be connected, later, to earth;
  • Class 2 switches are made of polyester, and the insulation measures are more restricted. The electrical panel is equipped with a ground bus to which all protective conductors will be connected, without the housing being connected to earth.


To increase the efficiency and performance of a generator, it is essential to choose the best components, which help to meet the needs and requirements of each customer in an exemplary way.

Grupos electrogéneos Grupel+Grupel - Energia de Portugal para o Mundo