The 3RU11 thermal overload relays up to 100 A are designed for current-dependent protection of applications with normal start-up conditions against impermissibly high rises in temperature as a result of overload or phase failure. An overload or phase failure causes the motor current to rise above the set rated motor current. This current rise heats up the bimetal strips within the relay via heating elements which, in turn, operate the auxiliary contacts via a tripping mechanism due to their deflection . These switch the load off via a contactor. The switch-off time is dependent on the ratio of tripping current to operational current Ie and is stored in the form of a tripping characteristic with long-term stability. The Tripped state is signalled by means of a switching position indicator. Resetting takes place manually or automatically after a recovery time has elapsed.