What it is and what it does
The Siemens 3VA1025-4ED32-0BC0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection in three-phase distribution. It carries a rated continuous current Iu of 25 A and a rated insulation voltage Ui of 800 V, so it handles standard 400 VAC panels with headroom to spare. Breaking capacity is specified at four voltage points: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. For a 415 V industrial feeder, that 75.6 kA figure means it can interrupt a bolted fault without upstream fuses needing to clear first — useful for selectivity in a motor control center. The overcurrent release is a TM210 thermal-magnetic type — fixed thermal and magnetic settings, no electronic adjustment. That keeps the part simple for standard feeder protection but means you cannot dial in a lower magnetic pickup for a long motor start.
Thermal derating and panel fit
Current rating holds at 25 A from 40 °C through 50 °C ambient. Above that it steps down: 24 A at 55 °C, 23.5 A at 60 °C, 23 A at 65 °C, and 22.5 A at 70 °C. If the panel ambient runs near 60 °C, the breaker is effectively a 23.5 A device — factor that into the load schedule. Dimensions are 130 mm height, 76.2 mm width, 70 mm depth. The 76.2 mm width is a standard 3-pole MCCB footprint — it fits existing SENTRON busbar systems and most DIN-rail adapter plates without panel modifications. Front-face protection is IP40, so it keeps out tools and fingers but is not sealed against hose-down. Mount it inside a panel rated for the environment.
Auxiliary contacts and undervoltage release
This unit ships with two auxiliary switches (HQ type) and an undervoltage release (UVR). The UVR trips the breaker when control voltage drops below a threshold — standard for safety circuits that need a loss-of-voltage shutdown. The auxiliary switches provide status feedback to a PLC or indicator lamp. Mechanical endurance is rated at 15 000 operations — typical for a distribution breaker that cycles infrequently. Not a switching duty device for frequent motor starts.