The Siemens SENTRON 3VA2163-7HK36-0AA0 is a 3-pole molded case circuit breaker rated for 63 A continuous current, fitted with an ETU340 electronic overcurrent release. At 690 V it still clears 53 kA, so it handles the low-side of a 690 V distribution transformer without needing a current-limiting fuse upstream.
Rated continuous current Iu holds flat at 63 A from 40 °C all the way to 70 °C — no derating curve to chase in a hot panel. The ETU340 release is adjustable for long-time delay (tr) at a fixed 1300 ms, which is a narrow window for coordination; verify it plays with your downstream breaker curves before committing the BOM line. Power loss maxes at 4 W — negligible for panel thermal budgeting but confirms the contact resistance is tight.
Where it lives in the panel
The 3VA2 frame is a standard Siemens SENTRON MCCB footprint: 105 mm wide, 181 mm tall, 86 mm deep. Optional motor drive can be added for remote trip/reset; the base unit ships without it.