MCC Panels

Moulded Case Circuit Breakers (MCCB) in Soft Starter Panel

Moulded Case Circuit Breakers (MCCB) selection, integration, and best practices for Soft Starter Panel assemblies compliant with IEC 61439.

Moulded Case Circuit Breakers (MCCB) in Soft Starter Panel

Overview

Moulded Case Circuit Breakers (MCCB) are a core protective device in soft starter panel assemblies, where they provide feeder isolation, overload protection, short-circuit protection, and discrimination with upstream switchgear. In a typical IEC 61439-2 low-voltage assembly, MCCBs are selected to suit the motor starting profile, panel busbar capacity, prospective short-circuit current, and the thermal constraints created by soft starters, bypass contactors, control transformers, PLCs, and ventilation components. For motor feeders, MCCBs are commonly used in ratings from 16 A up to 1600 A, with thermal-magnetic or electronic trip units, adjustable long-time, short-time, instantaneous, and earth-fault protection functions. In higher duty installations, ACB incomers may feed the assembly, while MCCBs protect individual soft starter branches and auxiliary circuits. In a soft starter panel, MCCB selection must account for inrush and starting torque requirements, even though the soft starter limits motor current during ramp-up. The breaker must tolerate the controlled starting current without nuisance tripping while still clearing genuine faults quickly. This is especially important for applications such as pumps, compressors, conveyors, HVAC fans, crushers, and process skids, where repeated starts can impose thermal stress on both the MCCB and the enclosure. Coordination is typically verified against the soft starter manufacturer’s current profile, with attention to Type 1 or Type 2 coordination where contactor, overload, and semiconductor protection requirements apply. For electronically controlled soft starters, MCCBs with adjustable trip settings and high interrupting capacity are preferred to maintain selectivity with upstream devices. From a construction standpoint, the panel should be designed in accordance with IEC 61439-1 and IEC 61439-2, with verification of temperature rise, dielectric properties, short-circuit withstand strength, and creepage/clearance distances. The chosen MCCB must have an ultimate short-circuit breaking capacity Icu and service breaking capacity Ics appropriate for the system fault level, often 25 kA, 36 kA, 50 kA, 70 kA, or higher depending on the installation. The busbar system, cable terminations, and mounting arrangement must be coordinated so that the MCCB’s let-through energy does not exceed the assembly’s withstand capability. Where multiple outgoing soft starter feeders are installed, form of separation, typically Form 2, Form 3, or Form 4, may be used to improve safety and maintainability, provided thermal and internal arc considerations are addressed. Modern MCCBs can be equipped with auxiliary contacts, shunt trips, undervoltage releases, motor operators, and communication modules for SCADA and BMS integration. This enables remote monitoring of breaker status, trip history, and operational alarms within intelligent motor control centers. In demanding environments, additional design checks may reference IEC 60947-2 for breaker performance, IEC 61641 for internal arcing robustness, and IEC 60079 where the panel is intended for hazardous area interfaces. Patrion designs and manufactures soft starter panels with MCCB coordination optimized for real-world motor control duty, ensuring reliable protection, thermal stability, and compliance-ready documentation for EPC contractors, industrial facilities, and OEM skids.

Key Features

  • Moulded Case Circuit Breakers (MCCB) rated for Soft Starter Panel operating conditions
  • IEC 61439 compliant integration and coordination
  • Thermal management within panel enclosure limits
  • Communication-ready for SCADA/BMS integration
  • Coordination with upstream and downstream protection devices

Specifications

PropertyValue
Panel TypeSoft Starter Panel
ComponentMoulded Case Circuit Breakers (MCCB)
StandardIEC 61439-2
IntegrationType-tested coordination

Other Components for Soft Starter Panel

Soft Starters

Reduced voltage motor starting, torque control, bypass options

Contactors & Motor Starters

DOL/star-delta/reversing starters, overload relays, Type 2 coordination

Busbar Systems

Copper/aluminum busbars, busbar supports, tap-off units

Protection Relays

Overcurrent, earth fault, differential, generator protection relays

Other Panels Using Moulded Case Circuit Breakers (MCCB)

Main Distribution Board (MDB)

Primary power distribution from transformer to sub-circuits. Rated up to 6300A. Houses main incoming breaker, bus-section, and outgoing feeders.

Power Control Center (PCC)

High-capacity power distribution for industrial facilities. Controls and distributes incoming power to MCC, APFC, and downstream loads.

Motor Control Center (MCC)

Centralized motor control with starters, contactors, overloads, and VFDs in standardized withdrawable/fixed functional units.

Power Factor Correction Panel (APFC)

Automatic capacitor switching for reactive power compensation. Thyristor or contactor-switched, detuned or standard configurations.

Automatic Transfer Switch (ATS) Panel

Automatic changeover between mains and generator/UPS. Open or closed transition, with or without bypass.

Variable Frequency Drive (VFD) Panel

Enclosed VFD assemblies with input protection, line reactors, EMC filters, output reactors, and bypass options.

Generator Control Panel

Genset start/stop sequencing, synchronization, load sharing, and paralleling controls.

Metering & Monitoring Panel

Energy metering, power quality analysis, and multi-circuit monitoring with communication gateways.

Lighting Distribution Board

Final distribution for lighting and small power. MCB/RCBO-based with DALI or KNX integration options.

Busbar Trunking System (BTS)

Prefabricated busbar distribution per IEC 61439-6. Sandwich or air-insulated, aluminum or copper.

PLC & Automation Control Panel

Process and machine control panels housing PLCs, I/O modules, relays, HMIs, and communication infrastructure.

Custom Engineered Panel

Bespoke panel assemblies for non-standard requirements — special ratings, unusual form factors, multi-function combinations.

Harmonic Filter Panel

Active or passive harmonic filtering to mitigate THD from non-linear loads. Tuned LC filters, active filters, or hybrid configurations.

DC Distribution Panel

DC power distribution for battery systems, solar installations, telecom, and UPS applications. MCCB/fuse-based DC protection.

Capacitor Bank Panel

Fixed or automatic capacitor bank assemblies for bulk reactive power compensation in industrial and utility applications.

Frequently Asked Questions

MCCB sizing in a soft starter panel is based on the motor full-load current, the soft starter’s starting current profile, the cable ampacity, and the required short-circuit withstand rating. The breaker must allow the controlled ramp-up current without nuisance tripping, while still protecting the feeder and downstream equipment. In practice, engineers verify the MCCB’s adjustable long-time and instantaneous settings, then coordinate them with the soft starter manufacturer’s application data. Compliance should be checked against IEC 60947-2 for breaker performance and IEC 61439-2 for assembly verification. For repeated-start applications, thermal derating inside the enclosure is also critical because the breaker and soft starter both contribute to heat rise.
The MCCB’s breaking capacity must be equal to or greater than the prospective short-circuit current at the point of installation. In soft starter panels, this is often specified as Icu and Ics values such as 25 kA, 36 kA, 50 kA, or 70 kA at the system voltage, but the correct value depends on the network fault level and the upstream transformer impedance. The assembly also has to satisfy IEC 61439 short-circuit withstand verification, meaning the busbars, supports, and terminals must withstand the same fault duty. If the panel is installed in a plant with high fault levels, current-limiting MCCBs or coordinated upstream ACB/MCCB protection may be used to improve selectivity and reduce let-through energy.
Yes, but Type 2 coordination is not determined by the MCCB alone. Type 2 coordination depends on the complete protective chain: MCCB, soft starter semiconductor protection, bypass contactor, overload function, and the manufacturer’s tested combination. IEC 60947-4-2 governs soft starters, while the breaker must be properly coordinated for short-circuit and overload events. In practice, engineers use the soft starter supplier’s coordination tables to confirm whether the assembly can remain operational after a fault, with only the affected component replaced if necessary. This is important in critical process applications where downtime must be minimized.
Electronic trip units are often preferred in soft starter panels because they offer adjustable long-time, short-time, instantaneous, and earth-fault settings, which improve selectivity and coordination. Thermal-magnetic MCCBs can still be suitable for smaller feeders or simpler applications, but they offer less flexibility when matching the starting curve of a motor controlled by a soft starter. In industrial MCC panels, electronic trips are especially useful when the panel is integrated into SCADA or BMS systems, because status, alarms, and trip information can be monitored remotely via communication accessories. Selection should still be based on IEC 60947-2 performance and the actual load profile.
An MCCB contributes to total panel temperature rise through its own losses, the cable terminations, and any auxiliary accessories such as shunt trips or motor operators. In a soft starter panel, this matters because the soft starter power semiconductors and bypass contactor also generate heat. Under IEC 61439-1 and IEC 61439-2, the assembly must be verified for temperature rise at the declared rated current. If the enclosure is compact or installed in a warm plant room, derating may be necessary. Proper spacing, busbar sizing, ventilation, and terminal selection help keep the MCCB within its thermal limits and preserve long-term reliability.
Communication modules are not mandatory, but they are increasingly specified in modern soft starter panels for remote status monitoring and maintenance planning. An MCCB with auxiliary contacts, alarm contacts, or a communication accessory can report breaker open/closed state, trip indication, and in some models measured current or energy data. This supports SCADA, BMS, and IIoT integration and helps facilities track motor feeder events. For panel builders, communication-ready breakers simplify diagnostics, especially in applications with many pumps or fans. The electrical design still has to comply with IEC 61439-2, and the communication hardware should not compromise creepage, clearance, or thermal performance.
An MCCB offers resettable protection, adjustable trip settings, and easier maintenance, while a fuse switch provides very high fault-current limitation and often lower upfront cost. In soft starter panels, MCCBs are frequently preferred because they integrate better with coordination studies, remote indication, and selective tripping strategies. Fuses can still be used where extremely high prospective fault levels require strong current limitation, but replacement after operation adds maintenance effort. The choice should be made based on the project’s fault level, operating philosophy, and compliance with IEC 61439 and IEC 60947-2, as well as the soft starter manufacturer’s recommended protection scheme.
The main assembly standard is IEC 61439-2 for power switchgear and controlgear assemblies, which covers the panel as a whole. The MCCB itself is evaluated under IEC 60947-2, while the soft starter is typically assessed under IEC 60947-4-2. If the panel is used in hazardous atmospheres or interfaces with such areas, IEC 60079 requirements may also apply, and internal arcing considerations may reference IEC 61641. In practice, the panel builder must verify coordination, temperature rise, dielectric properties, and short-circuit withstand as part of the complete assembly, not just the individual components.

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