Siemens SENTRON 3VA1050-3ED36-0DA0 — 50 A MCCB with Undervoltage Release
The Siemens SENTRON 3VA1050-3ED36-0DA0 is a 3-pole molded case circuit breaker (MCCB) rated 50 A at 40 °C, designed for line protection in distribution panels and motor branch circuits. It carries a TM210 thermal-magnetic release — the TM210 designation means the thermal element is fixed at 100% of the frame rating and the magnetic pickup is set at 10x In (500 A instantaneous), a common setting for general-purpose feeder protection. An integrated undervoltage release (UVR) trips the breaker when control voltage drops below a set threshold, adding a layer of safety for motor starters or emergency-stop circuits.
Breaking Capacity and Coordination
Breaking capacity varies significantly with system voltage: 75.6 kA at 240 V, 52.5 kA at 415 V, 32 kA at 440 V, and 7.5 kA at 500 V or 690 V. At 415 V — the common low-voltage distribution level in many industrial plants — the 52.5 kA rating provides substantial fault-current headroom for most panelboards. At 690 V the 7.5 kA figure is lower, so verify the available fault current if the breaker is applied on a 690 V system. The insulation voltage is rated 800 V, so the breaker is electrically suitable for 690 V circuits despite the reduced interrupting capacity.
Thermal Derating and Ambient Temperature
The breaker holds its full 50 A rating up to 50 °C ambient. Above that it derates linearly: 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. In a sealed panel with poor airflow, factor in the actual enclosure ambient — at 60 °C you lose 2 A of headroom. The maximum operating temperature is 70 °C; storage range is -40 °C to 80 °C. Power loss at rated load is 17.1 W maximum, which matters for heat buildup in a crowded DIN-rail enclosure.