Plant engineers use these devices to protect squirrel-cage and PM motors from overload, phase loss, and short-circuit stress while providing a local isolator on the machine. Frames cover fractional kilowatts up to ~55 kW at 400 V (typical setting ranges 0.1…100 A by frame), with rotary toggle or door-coupled handles and positively driven trip indication. Coordination with contactors and soft starters is standard practice, so starter assemblies clear faults without welding and go back in service fast.

siemens motor breakers Range and coordination

Siemens lines span compact manual starters for single-motor feeders and higher-capacity breakers that mount on 35 mm DIN or backplates. Trip units combine a thermal release (adjustable to motor FLA) and a magnetic release for short-circuit protection; instantaneous pickup is fixed or adjustable depending on frame (often ~12×…14× In). Type 1 / Type 2 coordination tables with matched contactors simplify tendering: choose the kW node and fault level, then pick the listed pair to guarantee either repairable (Type 1) or non-deteriorating (Type 2) outcomes after a bolted fault. Rotary handles padlock in OFF for LOTO, and door interlocks prevent live-door opening unless defeated with a tool by authorized staff.

Other Siemens products

Pushbutton 3SB3 22mm round metal blue flat momentary

Pushbutton 3SB3 22mm round metal white flat momentary

Pushbutton 3SB3 22mm round plastic red flat momentary

Pushbutton 3SB3 22mm round plastic black flat momentary

Pushbutton 3SB3 22mm round plastic green flat momentary

siemens mpcb devices Technical specifications and standards

Conformity: IEC/EN 60947-4-1 for motor-starter protectors, IEC/EN 60947-2 for the breaker function, and IEC/EN 60947-1 general rules. Utilization categories AC-3/AC-53a apply to the associated contactor or soft starter; the MPCB itself handles manual switching and fault clearing. Frames declare Icu/Ics at 230/400/690 V—expect 10…25 kA standalone and higher ratings in listed fuse-backup schemes. Thermal class tolerates −25…+55 °C operation (storage to +80 °C); altitude derating curves are published. Terminals accept ~0.75…25 mm² on small bodies and up to 50 mm² on larger frames; IP20 finger-safe with terminal shrouds. Trip-class behavior supports motor curves per IEC 60947-4-1 (typical tripping aligns with Class 10/10A for general drives; check Class 20/30 for high-inertia loads). Accessories include auxiliary OF/SD, alarm contacts, shunt/undervoltage trips, phase-loss sensitive releases, and differential-phase add-ons where specified.

siemens motor control protection Applications and compatibility

Use MPCBs ahead of contactors in fans, pumps, conveyors, mixers, and compressors—anywhere locked-rotor current must be interrupted quickly and overloads need repeatable thermal response. For VFD feeders, place the MPCB upstream of the drive; set the thermal dial to cable/drive input current, not motor nameplate, and let the drive handle motor-side protection. Where multiple small motors share a feeder, group with individual MPCBs downstream of a common MCB; diversity on start helps avoid nuisance trips. In harsh or washdown zones, add door-coupled handles with IP65 kits and stainless shafts.

Integration with Siemens starters, drives, and panels

Breakers couple directly to SIRIUS contactors via wiring-free adapter blocks to form compact DOL or reversing starters. Soft-starter lines and SINAMICS drives upstream benefit from the breaker’s magnetic cut-off during mains-side faults; use the Siemens tables for fuse-assisted Icc where the plant fault level exceeds the breaker’s stand-alone Icu. SENTRON busbar systems and 3-phase distribution accessories reduce panel time; feed-through variants streamline daisy-chain MCC sections. Auxiliary outputs wire cleanly to S7/ET 200 safe inputs for permissives and trip alarms.

Selection criteria for B2B buyers

Start with motor data: kW, FLA at operating voltage, service factor, and starting method (DOL, star-delta, soft start, VFD). Choose the setting range so the thermal dial sits mid-scale at the actual FLA; that preserves calibration headroom across ambient swings. Verify Icu/Ics against the board’s prospective fault level and any fuse-backup scheme. Pick coordination Type 1 or Type 2 per plant policy, then select the matched contactor. Confirm terminal capacity and conductor class (solid, stranded, ferruled). For high-inertia loads, check trip-class fit; Class 20 avoids nuisance during long accelerations. If the spec mentions siemens compact circuit breakers in the same assembly, keep them for feeder protection and discrimination—use the MPCB only for the motor branch. Where local isolation is required, add door handles with padlock hasps sized to your LOTO policy.

Practical notes and accessories

Plan depth: door-coupled shafts have cut tables by enclosure depth; wrong length side-loads the bushing. Mount thermal sensors near heat sources with consideration for de-rating; MCC cubicles often run 10–15 K above ambient. For multi-motor skids, use common auxiliary alarm contacts to a single PLC point to speed diagnostics. Where techs expect a single device to start/stop and trip, specify siemens motor starter breakers with integrated ON/OFF operators. For legacy panels that still reference thermal relays, MPCBs can replace MCB+relay stacks and free rail space; just verify the enclosure’s short-circuit study.

Cross-references and specification language

In tender text, call out breaker frame, setting range, Icu/Ics at system voltage, coordination type with contactor model, handle style (panel vs door-coupled), and accessories (OF/SD, UVR, shunt). Where feeders require enhanced thermal sensitivity or frequent switching, note siemens overload protection breakers explicitly so procurement cannot substitute general-purpose MCBs. For packaged equipment, OEMs often prefer quick-connect busbar kits to reduce assembly minutes per starter.

Advantages of working with Bankoflamps

We align motor kW nodes, setting ranges, coordination pairs, and handle kits to your one-line and MCC elevations, then surface live EU stock by warehouse before shutdown windows get booked. Quotations typically return in about an hour with EAN/MPN, Icu/Ics at your system voltage, thermal/magnetic ranges, and accessory lists—so ratings don’t drift mid-phase. The client portal shows lead times, order status, and downloadable price lists with validity dates; approved partners can use post-payment up to 30 days. We consolidate by board section or machine cell to cut freight and on-site sorting, and your account manager checks fault level, discrimination with upstream protection, enclosure depth, shaft length, and wiring class against drawings—so crates arrive build-ready and electricians terminate once.