It's a line-protection device — meaning it guards distribution feeders and branch circuits against overload and short circuit, not motor-protection curves. With the shunt trip (STL) accessory factory-installed (order code 3VA9688-0BL33), this breaker can be remotely tripped from an emergency-stop circuit or a PLC digital output. The 2 auxiliary switches HQ provide status feedback — closed/ tripped — back to a control system or annunciator panel.
Breaking capacity — the so-what for selectivity
This breaker delivers 52.5 kA at 240 VAC, 32 kA at 415 VAC, 13.6 kA at 440 VAC, and 7.5 kA at 690 VAC. Those numbers govern whether it coordinates with an upstream feeder breaker or transformer. At 415 V, 32 kA is enough for most secondary switchboards downstream of a 1 MVA transformer; at 690 V, the 7.5 kA figure means it's suited for lower-fault industrial loads, not high-fault mining or marine distribution. The 50 A frame at 40–50 °C is fully rated — no derating until 55 °C, where it drops to 48 A, then 47 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. That thermal curve lets you push the breaker into a warm enclosure as long as ambient stays under 50 °C.
Mechanical endurance and environmental limits
Rated for 15,000 mechanical operations — that's typical for a distribution breaker that sees infrequent switching, not a contactor duty cycle. Dimensions: 130 mm height, 101.6 mm width, 70 mm depth — fits standard 4-pole MCCB panel cutouts.