What it is and what it does
The Siemens 3RB3026-2VB0 is a SIRIUS solid-state overload relay in the S0 frame size, rated for a thermal current of 32 A and a rated insulation voltage of 690 V. It's the component that sits between your contactor and motor, watching for overcurrent conditions and tripping on a CLASS 20E curve — that means it allows a 20-second overload at 7.2× the current setting before it opens, which is the standard match for standard-duty induction motors starting under load. The integrated auxiliary switch gives you a separate signaling contact (Note: for message "tripped") so the PLC or annunciator knows exactly when the relay has operated.
Mounting and wiring reality
This relay mounts directly onto the contactor — no DIN rail needed, no extra bracket. Fastening method is contactor mounting, so it clips onto the matching SIRIUS contactor and the power connections pass through. The main circuit uses screw-type terminals accepting 1x (0.5...4 mm²) solid or 2x (0.5...2.5 mm²) stranded, and the main contacts take M4 screws. For the power wiring, stranded 2x 10 mm² is also listed. The auxiliary contact terminals use a smaller Pozidriv PZ 2 screwdriver tip. Overall dimensions: 45 mm wide, 87 mm high, 84 mm deep — it's a compact S0 footprint that fits into standard panel layouts without surprises. Mounting position is any, so you can orient it however the cabinet layout demands.
What the ratings mean for your line
The 32 A thermal current is the continuous current the relay can carry without tripping — that's the number you match to your motor's full-load amps. The CLASS 20E trip class means the relay won't nuisance-trip on a normal motor start but will clear a sustained overload before the motor insulation takes damage. The auxiliary contact ratings tell you what the signaling circuit can handle: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V — all AC values for the "tripped" signal contact. The operating temperature range of -25 to +60 °C covers most indoor industrial environments, and the temperature compensation keeps the trip curve accurate across that span. Shock resistance of 15g / 11 ms and vibration resistance per IEC 60068-2-27 mean it survives the typical bumps of a running machine.