ATCONTROL/R PT protectors also actuate when they detect a transient overvoltage, diverting the current to earth and reducing the voltage to a level that does not damage the connected equipment.
The warning system for permanent overvoltages consists of two luminous indicators: green (correct power supply) and red (overvoltage). It has a test button to check that installation has been executed correctly.
It has a thermodynamic control device that disconnects from the electrical network in case of deterioration, and also a warning system for transient overvoltages. When the warning is yellow, the protector is in good condition. If not, replace.