What this MCCB is and where it fits
The Siemens SENTRON 3VA1020-4ED32-0DH0 is a 3-pole molded case circuit breaker (MCCB) rated for 20 A continuous at 40 °C, designed for line protection in distribution panels and industrial switchboards. Its 70 mm depth, 76.2 mm width, and 130 mm height fit standard Siemens 3VA panel footprints — a direct drop-in for existing SENTRON 3VA busbar and mounting arrangements.
Breaking capacity — what the ratings mean for coordination
Breaking capacity is the current the breaker can safely interrupt at a given voltage without welding contacts or failing. This unit delivers 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That 121 kA figure at 240 V is high for a 20 A frame — it allows the MCCB to be used downstream of large transformers or in high-fault-capacity panels without needing a current-limiting fuse upstream. At 690 V the 11.9 kA still covers most motor-circuit fault levels.
Integrated undervoltage release and auxiliary switching
Factory-fitted with an undervoltage release (UVR) and a complement of two auxiliary switches plus one trip-alarm switch (HQ). The UVR trips the breaker when control voltage drops below a threshold — standard for safety circuits that need to drop power on loss of control supply. The auxiliary switches provide status feedback to a PLC or indication lamp; the HQ switch signals a trip event separately from manual open. All share the same compact housing, so no external add-on modules are needed.
Current rating across temperature — no derating needed up to 55 °C
Rated 20 A from 40 °C through 55 °C ambient — no derating required in most panel environments. At 60 °C and 65 °C it holds 19 A, and at 70 °C still delivers 19 A. That thermal stability simplifies panel design: you don't need to oversize the frame for a warm enclosure. Maximum power loss is 14.5 W, which is moderate for a 20 A MCCB and manageable in a standard IP54 cabinet.