What it is and what it does
The Siemens 3RV1021-1FA15-ZW98 is a SIRIUS motor protection circuit breaker designed for motor protection in control panels. It combines a 5 A continuous current rating with a Class 10 trip curve, meaning it protects motors against overload and short-circuit while allowing the higher inrush during start-up. The breaker handles 1.5 kW at 400 V AC (AC-3 duty) and delivers a 100 kA breaking capacity at 400 V AC — enough to clear a hard fault without cascading upstream.
Mounting and integration
Mounts via screw or snap-on onto a 35 mm standard mounting rail per DIN EN 50022. The footprint is 45 mm wide, 97 mm high, and 96 mm deep — a standard 45 mm module width that fits alongside contactors and relays in a typical panel layout. The front face carries an IP20 rating, so it's safe for finger contact inside an enclosure. Mounting position is any orientation, which helps when you're cramming gear into a tight gland plate.
Breaking capacity and fault handling
Breaking capacity is 100 kA at 240 V, 400 V, and 500 V AC, dropping to 6 kA at 690 V AC. That 100 kA at 400 V means it can interrupt a fault current up to 100,000 amps without welding contacts or blowing apart — critical when the panel feeds a high-capacity transformer. Phase failure detection is built in, so a lost phase on the line side will trip the breaker and protect the motor from single-phasing. No ground fault detection on this variant.
Terminal wiring and aux contacts
Main current circuit terminals are screw-type. Solid conductors: 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²). Stranded: 2x (1 to 2.5 mm²) and 2x (2.5 to 6 mm²). The auxiliary switch is transverse design and rated: 1 A at 24 V, 0.5 A at 230 V, 0.15 A at 60 V. No auxiliary contacts are included as standard — the auxiliary switch is built into the breaker body.