What the key ratings mean for fit
The Siemens SENTRON 3VA1120-4EF36-0HC0 is a 3-pole molded case circuit breaker (MCCB) rated for 20 A continuous current across a wide ambient range — full 20 A from 40 °C up to 50 °C, then derating to 18 A at 70 °C. This means the breaker holds its rating in warm enclosures without needing to oversize, provided the panel ambient stays below 50 °C. Above that, the thermal curve in the TM240 trip unit governs the actual continuous current. Interrupting capacity is the headline: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and still 11.9 kA at 690 V. That high fault-current handling at 240 V and 415 V means this MCCB can be used in high-available-fault-current distribution panels without needing a current-limiting upstream fuse — it clears the fault within its own rating. The 690 V figure is low enough that for 690 V systems, check the available fault current against the 11.9 kA limit. The TM240 thermal-magnetic trip unit provides overload and short-circuit protection in one package — no electronic adjustments, but also no auxiliary power needed to maintain the trip curve. For a line-protection MCCB, that's a straightforward, field-proven design.
Shunt trip and auxiliary switches — remote tripping built in
This version ships with a shunt trip (STL) release (design code 3VA9688-0BL30) and two auxiliary switches HQ. The shunt trip allows remote opening of the breaker via a control signal — typical for emergency-stop circuits or remote load shedding in an automated warehouse shuttle system, where a stalled crane blocking an aisle needs a remote breaker trip without sending a technician into the racking. The two auxiliary switches HQ provide status feedback (open/closed) to a PLC or SCADA — useful for confirming the breaker state in a safety-rated motion control architecture. The IP40 front protection means the operator interface is sealed against tools and small objects, but the breaker is intended for indoor panel mounting, not washdown environments.
Panel footprint and mounting
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — a compact 3-pole MCCB footprint that fits standard DIN-rail or panel-mount cutouts. The 76.2 mm width (3 modules of 25.4 mm) matches the typical 3-pole modular breaker slot in a SENTRON distribution board, so it drops into existing panel layouts without rewiring the busbar.