20 A MCCB with 75.6 kA breaking capacity — line protection for distribution panels
The Siemens SENTRON 3VA1020-3ED36-0JC0 is a 3-pole molded case circuit breaker rated 20 A continuous at 40 °C, designed for line protection in power distribution. Its breaking capacity hits 75.6 kA at 240 V AC, dropping to 52.5 kA at 415 V and 7.5 kA at 690 V — so it handles high fault currents on the secondary side of a distribution transformer without cascading upstream. The 70 mm depth and 76.2 mm width fit standard panel cutouts, and the included shunt trip (STL) plus two HQ auxiliary switches give you remote trip and status feedback without adding external modules.
Rated current holds flat across the panel ambient range
The 20 A rating is continuous at ambient temperatures from 40 °C through 55 °C — no derating needed in a warm enclosure. At 60 °C it still holds 19 A, and at 70 °C it holds 19 A. That gives you headroom in a crowded panel where internal temperature runs 10–15 °C above room ambient. The insulation voltage is rated 800 V, so the breaker can sit on a 690 V bus without derating the dielectric.
Breaking capacity by voltage — selectivity planning
The 75.6 kA at 240 V is the headline number, but the real-world selectivity decision happens at the system voltage. At 415 V it breaks 52.5 kA, at 440 V it drops to 32 kA, and at 500 V and 690 V it holds at 7.5 kA. If your fault current at the panelboard exceeds 32 kA at 440 V, you need an upstream current-limiting fuse or a higher-rated MCCB. The 7.5 kA at 690 V is typical for a downstream feeder breaker in a 690 V drive system — adequate for most motor branch circuits.
Dimensions and panel fit
The breaker measures 130 mm tall, 76.2 mm wide, and 70 mm deep. The 76.2 mm width is a standard 3-pole MCCB footprint — it fits the same DIN-rail or panel-mount cutout as other SENTRON 3VA1-frame breakers. Depth of 70 mm leaves room behind the panel door for wiring and the shunt trip coil. Maximum power loss is 12 W, so heat dissipation in a sealed enclosure is manageable.