What this MCCB is and what it carries
The Siemens 3VA1120-4EE46-0AA0 is a SENTRON molded case circuit breaker (MCCB) for line protection, rated 20 A continuous current (Iu) with a TM220 thermal-magnetic overcurrent release. It is a 4-pole unit, meaning it switches and protects all three phases plus neutral in a three-phase four-wire system — common for main incomers or feeder circuits where neutral protection is required.
Breaking capacity — what the numbers mean for coordination
Breaking capacity is the maximum fault current the breaker can safely interrupt at a given voltage. This MCCB is rated 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. At 415 V — the most common three-phase industrial voltage in IEC markets — 75.6 kA is a high-interrupting rating, suitable for installation close to large transformers or in high-fault-capacity switchboards where downstream breakers need a high upstream SCCR for selectivity.
Thermal derating and panel integration
The breaker holds its full 20 A rating up to 55 °C ambient. At 60 °C it derates to 19 A, and it stays at 19 A through 70 °C. The maximum operating temperature is 70 °C, storage range -40 °C to 80 °C. Rated insulation voltage (Ui) is 800 V. Power loss at rated current is 12 W — modest for a 4-pole MCCB, but worth accounting for in a sealed, uncooled enclosure with multiple breakers side by side. The front face carries IP40 protection; the rest of the body is unrated, so the breaker belongs inside a panel, not in a washdown zone.
What the TM220 release means for the installer
The TM220 designation means the thermal element (for overload protection) and the magnetic element (for short-circuit protection) are both fixed, not adjustable. The thermal pickup is calibrated to the 20 A frame rating; the magnetic instantaneous trip is set at the factory. The adjustable response value current (Ii max) is listed at 320 A — that is the maximum magnetic trip setting available on this release variant, not the actual setting, which is fixed. For applications needing field-adjustable overloads or short-circuit pickups, a different release (e.g., an electronic one) would be required.
DC rating and optional accessories
The maximum rated operational voltage for DC circuits is 600 V. The product extension field indicates a motor drive accessory is available as an option — this typically refers to a rotary handle or motor operator for remote or panel-door operation. No communication function is built in; this is a plain electromechanical MCCB.