Siemens SENTRON 3VA1020-3ED32-0BA0 — 20 A MCCB with undervoltage release
The Siemens SENTRON 3VA1020-3ED32-0BA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current Iu of 20 A at ambient temperatures up to 50 °C, with a slight derating curve above that — 19.2 A at 55 °C down to 18 A at 70 °C. The TM210 thermal-magnetic release handles overload and short-circuit protection; the interrupting capacity hits 75.6 kA at 240 V and 52.5 kA at 415 V, which covers most industrial distribution panels and motor control center infeeds. The built-in undervoltage release (UVR) trips the breaker when control voltage drops, so this unit is suited for applications where loss-of-voltage protection is required — emergency stops, safety circuits, or any line that needs to drop on undervoltage.
What the interrupting ratings mean for your panel
The 75.6 kA at 240 V and 52.5 kA at 415 V tell you the maximum fault current this MCCB can safely clear at those voltages. In practice, that means it can be installed downstream of transformers or busbars with high available fault current — typical for 240 V distribution in North American panels or 415 V systems in IEC markets. At 690 V the rating drops to 7.5 kA, so if you're feeding a 690 V drive or motor circuit, verify the prospective fault current at that point doesn't exceed that figure. The 800 V rated insulation voltage (Ui) confirms the breaker's internal insulation is designed for 690 V line-to-line systems.
Panel fit and mounting
The 3VA1020-3ED32-0BA0 measures 76.2 mm wide, 130 mm high, and 70 mm deep — standard 3-pole MCCB footprint for the SENTRON 3VA platform. It mounts on a DIN rail or can be screw-fixed to a backplate. The front face carries IP40 protection, so it's fine for enclosed panels but not for open washdown areas. No auxiliary contacts are fitted on this variant; if you need alarm or status signaling, the auxiliary trip accessory (order code 3VA9608-0BB11) can be added. No communication module or phase-failure detection is built in — this is a straightforward line-protection breaker.
Undervoltage release — what it does and why it matters
The undervoltage release (UVR) is a separate release coil that trips the breaker when its supply voltage falls below a threshold. On this unit, the UVR is factory-fitted (design: undervoltage release). That means the breaker will open if control power is lost — useful for preventing automatic restart after a voltage dip, or for integration into an emergency-stop chain where loss of the safety circuit should drop the breaker. There is no voltage trigger or trip indicator on this variant, so the only trip indication is the handle position.
Temperature derating — what 20 A really buys you
The 20 A rating holds flat from 40 °C to 50 °C. Above that, it derates linearly: 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. If your panel ambient runs hot — say, near a transformer or in a sun-exposed enclosure — factor that derating into your load calculation. The operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C.