What it is and what it does
The 3RV2021-1EA20: Trip Class 10 means it will trip within 10 seconds at 7.2× the thermal setting current — fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping on normal startup inrush. The 100 kA rated short-circuit breaking capacity at 400 V AC is the standout spec here: it can safely interrupt a fault current up to 100,000 amps at that voltage without welding contacts or venting plasma. That's full-rated SCCR for most industrial panels — no need for upstream current-limiting fuses unless the available fault current exceeds 100 kA. Rated insulation voltage of 690 V covers 480 V and 600 V class systems with margin. The breaker also includes phase failure detection — if one phase drops out, it trips the motor offline before single-phasing cooks the winding.
Panel fit and mounting
Mounts via screw fixing or snap-on onto 35 mm DIN rail per DIN EN 60715. The 45 mm width is the standard SIRIUS compact frame — fits alongside contactors and overloads in a motor starter lineup without eating extra rail space. Depth is 97 mm, height 119 mm. Any mounting position is allowed. Clearance requirements: 50 mm upwards and downwards, 30 mm at the sides, zero forwards or backwards. That side clearance is tighter than some competing breakers — good for dense panels, but verify if you're stacking multiple units side-by-side without derating. Spring-loaded terminals on the main circuit accept 2× (1 to 10 mm²) solid or stranded wire. No screw-clamp torque to check — just strip, insert, and the cage clamps. Saves time on the wireman's end of the panel build.
Environmental and duty limits
Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. The operating limit covers most indoor panel environments; if the panel sits in a non-conditioned space that hits 60 °C ambient, the breaker still holds its ratings. Maximum switching rate at AC-3 duty (motor starting) is 15 operations per hour. That's typical for a motor-protection breaker — it's not designed for high-cycling jogging or reversing service. If the application needs frequent starts, look at the contactor's rating; the breaker is the backup, not the workhorse.