What it is and what it does
The Siemens 3RB1065-1LG0 is an electronic overload relay rated 300...630 A, Class 10, in SIZE S10/S12 with connecting bars. It mounts directly on a 3TF68 or 3TF69 contactor or can be installed individually, with a manual reset. The Class 10 trip curve means it will trip within 10 seconds at 7.2× the current setting — appropriate for standard motor starting duty where the inrush does not need a longer delay.
Integration notes
The connecting bars are included, so no separate busbar kit is needed when mounting to the 3TF68/69 contactor. The S10/S12 frame size matches the contactor interface. Manual reset means the relay stays tripped until someone presses the reset button — a deliberate choice for applications where automatic restart after a fault is not acceptable.