What this MCCB is and what it does
The Siemens 3VM1220-4ED42-0AA0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 200 A continuous rating at 40 °C and uses a TM210 thermal-magnetic overcurrent release — a fixed-trip unit that combines a thermal bimetal for overloads and a magnetic coil for short-circuits, with no adjustable trip settings. The 4-pole configuration handles three-phase plus neutral, common in North American and European 3-phase 4-wire systems where the neutral must be switched or protected. The interrupting capacity tells you where this breaker can be installed safely: 121 kA at 240 V AC, 76 kA at 415 V AC, 53 kA at 440 V AC, and 17 kA at 500 V AC. That 121 kA at 240 V is high enough for most service-entrance or main-switchboard positions on a 240 V delta or 208Y/120 V system. At 415 V it still holds 76 kA, which covers heavy industrial feeders where fault currents can exceed 50 kA. The 500 V rating drops to 17 kA — still adequate for many 480 V panelboards, but verify the available fault current at the point of installation.
Thermal derating — the real-world current limit
The 200 A rating holds flat from 40 °C through 50 °C ambient. Above that it derates: 194 A at 55 °C, 188 A at 60 °C, 182 A at 65 °C, and 176 A at 70 °C. If the breaker lives in a hot enclosure — near a transformer, in a non-ventilated panel, or in a plant with high ambient heat — use the 55 °C or 60 °C column for sizing. The maximum operating temperature is 70 °C, and storage range is -40 °C to 80 °C.
Physical fit and panel integration
Dimensions are 70 mm deep, 140 mm wide, 158 mm high. That 70 mm depth is shallow enough for most 200 mm deep enclosures, leaving room for wiring gutters. The 140 mm width (5.51 in) is standard for a 4-pole MCCB in this class — it occupies three 18 mm pole spaces plus one neutral pole. Front IP40 protection means it is protected against tools and small wires but not against water ingress; mount it inside a panel or enclosure rated for the environment.
Key design details
The TM210 release is a fixed thermal-magnetic type — no interchangeable trip units, no adjustable long-time or short-time pickup. That makes it a straightforward choice for fixed-load feeders where coordination studies are done once and don't require field adjustment. It has no undervoltage release, no shunt trip, no ground-fault monitoring, and no communication function. Insulation voltage is rated 800 V. Maximum power loss is 42 W at rated current — factor that into enclosure thermal calculations.