Buy MPCB (Motor Protection Circuit Breaker) Online at Electrihub

A Motor Protection Circuit Breaker (MPCB), also known as a Manual Motor Starter (MMS) or Motor Circuit Protector, is a combined thermal-magnetic protection device purpose-built to protect three-phase motors against overload, short-circuit, and phase-failure conditions. Unlike a standard MCB, an MPCB has an adjustable current setting (FLA / rated operational current) that lets it be precisely calibrated to a motor's full load amperage — giving accurate overload protection while allowing the high inrush current of motor starting without nuisance tripping.

MPCBs are rated and tested to IEC 60947-4-1 (contactors and motor-starters) in combination with IEC 60947-2 for the breaking function, UL 508 (industrial control equipment / manual motor controllers) for the North American market, and CSA C22.2 No. 14 for Canada. They are classified by their adjustable current setting range, trip class (Class 10, 10A, 20, 30), number of poles (mostly 3P for three-phase motors, with 1P and 2P variants for control and auxiliary circuits), and breaking capacity (Icu/Ics), typically 50 kA–100 kA at 415–480 V depending on the frame size.

At Electrihub we stock MPCBs from globally trusted brands — Schneider Electric, ABB, Siemens, Eaton, and Lauritz Knudsen — covering every application from small fractional-horsepower motors to large industrial drives, with products listed to IEC, UL, CSA, and CE standards for international projects.

MPCB Trip Classes Explained — Class 10, 10A, 20, 30

The trip class defines how long an MPCB will tolerate an overload current before tripping — it directly affects motor protection and starting reliability. Selecting the correct trip class prevents nuisance tripping during normal motor start-up while still protecting the motor windings from sustained overload damage. Trip class ratings follow IEC 60947-4-1 and are equivalent to NEMA/UL trip class definitions used in North American motor circuit protectors.

Class 10A MPCB — Fast trip, ≤2 seconds at 7.2× FLA

Class 10A devices trip the fastest of the standard classes, suitable for motors with short, light starting duty — pumps, fans, and small compressors with low inertia loads. Class 10A offers the tightest motor winding protection and is the default choice where motor starting time is short.

Class 10 MPCB — Standard trip, ≤10 seconds at 7.2× FLA

Class 10 is the most widely used trip class globally, suitable for general-purpose motor applications with normal starting duty — conveyors, agitators, and standard industrial pumps. Class 10 is the default specification for most commercial and industrial motor circuits.

Class 20 MPCB — Delayed trip, ≤20 seconds at 7.2× FLA

Class 20 MPCBs are designed for motors with longer starting times and higher starting torque requirements — large centrifugal pumps, compressors, and high-inertia fans. The extended thermal delay prevents the MPCB from tripping during prolonged start-up while still protecting against genuine sustained overload.

Class 30 MPCB — Extended trip, ≤30 seconds at 7.2× FLA

Class 30 offers the longest permissible starting time, used for very high-inertia loads such as large crushers, ball mills, centrifuges, and heavy-duty industrial drives where extended ramp-up periods are required before the motor reaches full speed.

MPCB Current Setting Range & Short-Circuit Release

Adjustable Thermal Overload Setting — Every MPCB has a dial-adjustable current range (e.g., 1–1.6 A, 6–10 A, 23–32 A) that must be set to match the motor's nameplate full-load amperage (FLA). This thermal element provides true motor overload protection, replacing the need for a separate thermal overload relay in many manual starter applications.

Fixed Magnetic Short-Circuit Release — The instantaneous magnetic trip is factory-set, typically at 13× the maximum setting current, and protects the motor circuit and starter components against short-circuit faults. This release does not require field adjustment.

Poles — MPCBs are predominantly supplied in a 3-pole (3P) configuration to match the three-phase supply of the motor being protected. Some manufacturers offer combined 3P + auxiliary contact (1NO/1NC) modules for remote signalling, and rotary handle or door-interlock accessories are commonly added for safe isolation at the panel door.

MPCB Brands and Series – Technical Comparison Table

The table below compares every MPCB brand and series stocked by Electrihub. Use the current setting range, trip class, poles, breaking capacity, and certification columns to select the right product for your market, then click the series link to browse available stock.

All MPCBs are certified to IEC 60947-4-1 with breaking performance per IEC 60947-2. UL 508 and CSA C22.2 No. 14 listed variants are available on select series. Breaking capacity values are at 415 V AC (IEC) or 480 V AC (UL). Always verify individual product datasheets for market-specific certifications, exact setting ranges, and accessory compatibility (contactor mounting kits, rotary handles, auxiliary contacts).

About the MPCB Brands We Stock

Schneider Electric MPCBs — TeSys GV2, GV3

Schneider Electric's TeSys range is one of the most widely specified MPCB platforms worldwide. The TeSys GV2 ME covers small to medium motors from 0.1 A to 32 A, with magneto-thermal protection, rotary handle operation, and direct mounting for Schneider TeSys D contactors to form a compact combination starter. The TeSys GV3 ME extends the range to 65 A for larger motors. Both ranges carry dual IEC 60947-4-1 and UL 508 / CSA listings, making them suitable for OEM machine builders supplying both IEC and North American markets from a single design. The TeSys GV2 P is a pure motor circuit-breaker variant (without thermal overload, paired with a separate overload relay) used where decoupled short-circuit and overload protection is preferred.

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ABB MPCBs — MS116, MS132, MO132/MO150

ABB's manual motor starter range is engineered for global multi-standard compliance. The MS116 (0.1–16 A) and MS132 (0.16–32 A) cover small and medium motor applications with IEC 60947-4-1 and dual UL 508 / CSA listings, integrating directly with ABB AF and A-line contactors for combination starters. The MO132 / MO150 series extends protection up to 150 A for larger motors, offering Class 10 and Class 20 trip settings for high-inertia loads. ABB MPCBs feature a rotary operating handle with door-coupling rotary handle accessories for safe front-panel isolation, plus a full accessory range including auxiliary contacts, undervoltage releases, and shunt trips.

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Siemens MPCBs — 3RV2 (SIRIUS Compact), 3RV1 (SIRIUS Classic)

Siemens' SIRIUS MPCB family covers fractional-horsepower to large industrial motors globally. The 3RV2011 (0.11–16 A) and 3RV2021 (14–32 A) compact series carry UL 508 and CSA listings alongside IEC 60947-4-1, and mount directly to SIRIUS 3RT contactors for plug-and-play combination starters. The 3RV1031 SIRIUS Classic series extends protection from 22 A to 100 A with Class 10 and Class 20 trip settings, suited for larger industrial motor circuits, pump stations, and conveyor drive panels worldwide.

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Lauritz Knudsen MPCBs — MU, MK Series

Lauritz Knudsen (formerly L&T Electrical & Automation) offers IEC 60947-4-1 certified MPCBs manufactured in India. The MU series covers small and medium motors from 0.1 A to 32 A, while the MK series extends protection up to 100 A for larger industrial motors. Both ranges are widely specified in IEC-standard projects across Asia, the Middle East, and Africa, and integrate with L&T's MO and MX contactor ranges for compact combination starters.

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Eaton MPCBs — PKZM0, PKZM4, PKE

Eaton's PKZM0 (0.16–12 A) and PKZM4 (6–32 A) manual motor protectors are widely used in OEM panel building, carrying dual IEC 60947-4-1 and UL 508 / CSA listings for projects requiring simultaneous compliance across IEC and North American markets. The PKE series extends protection from 9 A to 100 A with Class 10 and Class 20 trip settings for larger industrial motor circuits. Eaton MPCBs mount directly to DILM-line contactors and support a wide accessory range including auxiliary contacts, shunt releases, and door-mounting rotary handles.

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Where Are MPCBs Used?

Direct-On-Line (DOL) Motor Starters — MPCBs combined with a contactor form a complete combination motor starter, replacing the traditional MCCB + thermal overload relay arrangement in a single compact, coordinated device used across virtually every industrial sector globally.

OEM Machine Building — Machine builders supplying equipment to multiple markets specify dual-listed MPCBs (UL 508 + IEC 60947-4-1) — such as Schneider TeSys GV2 ME, ABB MS132, Siemens 3RV2, or Eaton PKZM4 — to ship a single machine design to both IEC and North American customers without redesign.

Pumping Stations and HVAC Systems — MPCBs protect individual pump and fan motors in water treatment plants, HVAC air-handling units, and building services panels, with trip class selection matched to the starting characteristics of centrifugal or axial-flow loads.

Conveyor and Material Handling Systems — Industrial conveyor drives, packaging lines, and material handling equipment use MPCBs for individual motor branch protection within Motor Control Centres (MCCs), enabling fast isolation and reset for maintenance.

Compressors and High-Inertia Loads — Class 20 and Class 30 MPCBs protect large compressors, crushers, mills, and centrifuges where extended motor starting times require a longer thermal trip delay without compromising fault protection.

Process and Manufacturing Plants — Chemical, food and beverage, cement, and general manufacturing facilities use MPCBs throughout their MCCs and local control stations for coordinated, type-2 rated motor circuit protection.

How to Select the Right MPCB

Step 1 — Determine motor full load amperage (FLA)

Read the motor nameplate full-load current and select an MPCB whose adjustable setting range covers this value, ideally near the midpoint of the dial range rather than at either extreme, to allow margin for fine-tuning during commissioning.

Step 2 — Choose the correct trip class

Use Class 10A for light, fast-starting loads (small pumps, fans). Use Class 10 for general-purpose motors with normal starting duty — the most common choice globally. Use Class 20 for higher-inertia loads with longer starting times (large pumps, compressors). Use Class 30 for very high-inertia loads requiring extended ramp-up (crushers, mills, centrifuges).

Step 3 — Confirm pole configuration

Select a 3-pole (3P) MPCB for standard three-phase motor circuits — the configuration used in the vast majority of industrial applications. Add auxiliary contact blocks where remote trip signalling or interlocking with PLC/control circuits is required.

Step 4 — Verify breaking capacity and coordination type

The MPCB breaking capacity must exceed the prospective short-circuit current (PSCC) at the installation point. Confirm Type 1 or Type 2 coordination with the paired contactor and overload device per IEC 60947-4-1 — Type 2 coordination (no damage to the MPCB or contactor under fault conditions) is generally specified for critical industrial applications.

Step 5 — Confirm the required certification standard

For IEC markets (Europe, Middle East, Asia, Africa, Australia), specify IEC 60947-4-1 certified MPCBs. For North American projects, specify UL 508 listed manual motor controllers / motor circuit protectors. For projects requiring dual compliance, select multi-standard products such as Schneider TeSys GV2 ME/GV3 ME, ABB MS116/MS132, Siemens 3RV2, or Eaton PKZM0/PKZM4 — all carrying simultaneous IEC and UL/CSA listings.

Frequently Asked Questions — MPCB

What is the difference between MPCB and MCB?
An MCB is a fixed-rating device designed to protect general wiring and cables against overload and short-circuit. An MPCB has an adjustable current setting specifically calibrated to a motor's full-load amperage, plus a trip class designed to ride through motor starting inrush current — protection an MCB's fixed B/C/D curve cannot provide for a motor.

What is the difference between an MPCB and a thermal overload relay?
An MPCB combines short-circuit (magnetic) and overload (thermal) protection in a single device with a built-in isolating function. A thermal overload relay only provides overload protection and must be paired with a separate circuit breaker, fuse, or MPCB for short-circuit protection — an MPCB removes the need for that separate short-circuit device.

What is Type 1 and Type 2 coordination in motor starters?
Type 1 coordination (IEC 60947-4-1) permits damage to the contactor and overload device under short-circuit fault conditions, provided no danger to personnel results. Type 2 coordination requires no damage to either device — only light contact welding (easily separable) is permitted — and is the preferred specification for critical industrial motor circuits and OEM machine panels.

What does Trip Class 10, 10A, 20, and 30 mean?
The trip class defines the maximum time the MPCB will allow an overload current of 7.2× the set current to flow before tripping. Class 10A trips in 2 seconds or less (fast-starting loads), Class 10 in 10 seconds or less (general-purpose, most common), Class 20 in 20 seconds or less (high-inertia loads), and Class 30 in 30 seconds or less (very high-inertia loads).

Which MPCB brands carry both IEC and UL/CSA listings?
Several series on Electrihub carry dual IEC and UL 508 / CSA listings: Schneider Electric TeSys GV2 ME and GV3 ME, ABB MS116 and MS132, Siemens 3RV2011 and 3RV2021, and Eaton PKZM0 and PKZM4. These products allow OEM machine builders and panel manufacturers to supply equipment to both IEC and North American markets from a single certified product.

Can an MPCB be used without a contactor?
Yes — an MPCB can be used standalone as a manual motor starter for direct local on/off control and protection of a motor, commonly with a door-mounted rotary handle. For remote or automatic (PLC/relay-controlled) starting, the MPCB is mounted alongside a contactor to form a combination starter, with the MPCB providing protection and the contactor providing switching.

How do I set the current dial on an MPCB?
Rotate the adjustable dial on the front of the MPCB to match the motor's rated full-load current (FLA) as shown on the motor nameplate. Setting the dial too low causes nuisance tripping during normal operation; setting it too high removes effective overload protection and risks motor winding damage.

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Categories in Contactors and Contactor Relays

Auxiliary Contactors | Capacitor duty contactor | Motor Protection Relay | Motor Starter | MPCB | MPCB Accessories | Over Load Relay | Overload Relays Accessories | Power Contactor | Power Contactor Accessories | Protective Relays | Protective Relays Accessories