The Siemens 3RB3016-2RB0 is a SIRIUS solid-state overload relay in size S00, designed to protect motors against overload and phase failure. It mounts directly onto a contactor, saving DIN-rail space in the panel. Rated for a thermal current of 0.4 A at up to 690 V, this relay uses an electronic overload release with integrated auxiliary contacts — no bimetals to drift. The CLASS 20E trip curve means it tolerates normal motor inrush (up to 20 seconds at 600% of set current) before tripping, which suits most pump, fan, and conveyor applications.
For a motor with a full-load current of 0.4 A or less, this relay provides the right protection range — oversizing it would lose the low-end trip accuracy needed for small motors. The auxiliary contact ratings tell you what the signal circuit can switch: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V. These are the contacts that send the "tripped" message back to the PLC or annunciator — the relay's note specifically calls out this function (for message "tripped"). At 0.03 W per pole, the power dissipation in the main circuit is negligible, so no derating for heat buildup in a crowded panel. It mounts in any position and fastens directly to the contactor, not to the DIN rail, which saves a slot in the panel layout.
Environmental toughness
Built for the pit and the mill: the relay shrugs off vibration at 1-6 Hz with 15 mm amplitude and 6-500 Hz at 20 m/s² for 10 cycles. Shock resistance is 15g for 11 ms on the main contacts, and even the signaling contact in the tripped position takes 9g for 11 ms. That covers most industrial enclosures, including unheated warehouses.