Miniature circuit breakers

Protecting electrical equipment against damage

The number of electrical consumers continues to grow – and along with them the load on electrical systems. In the event of overload or a short-circuit, miniature circuit breakers (MCBs) safely cut the connected circuit and thus reliably protect electrical systems and devices against damage. Miniature circuit breakers (MCBs) in the SENTRON portfolio are also easy to assemble and install. The devices feature a uniform design, and can be expanded to include many more functions thanks to an extensive range of accessories. For industries, buildings or infrastructure – our extensive portfolio has the right MCB for every application.

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Overview of miniature circuit breakers (MCBs)

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Protection against electrical fires

Circuit breaker for equipment for protection of control circuits and equipment

In electrical installations many loads are fed by the same power supply. Under fault conditions the voltage supply must be maintained and loads not affected by the fault must remain unaffected. Circuit breakers for equipment are used for selective protection of individual devices and equipment in parallel in order to increase plant availability and protect against the consequences of overload and shortcircuit. If an overload or short-circuit occurs, these devices disconnect the corresponding circuit safely.
Devices for protection of control circuits and equipment

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New demands on electrical systems

Overload currents can occur, for example, when several electrical consumers are used simultaneously in the same circuit and exceed the maximum permissible current level. Short circuits, on the other hand, are conductive connections caused by errors, e.g. between phase and neutral conductor. Short circuits and overload currents can occur quite suddenly, for example, as a result of incorrect operation during switching, assembly errors or cases of higher forces, such as lightning strikes, earthquakes or flood disasters. It’s far more common, however, for them to occur gradually, as a result of age-related faults in cable insulation, plug connections or broken cables.


The risk of overload and short circuit is particularly high in residential and functional buildings, where the installed electrical systems and equipment are not subject to regular inspection. The growing number of electrical devices also contributes to the problem: an average household today uses much more than 50 electrical devices, compared to less than eight previously. Decentralized power producers like photovoltaic systems, or charging electric vehicles, place entirely new demands on electrical systems that may have been installed decades ago, according to the state-of-the-art at the time, but now require expanded protection measures. The same applies to industrial environments: just a few seconds without power is enough to bring production lines to a standstill, disrupt automation systems or compromise entire production batches. Preventive protection of industrial systems against electrical faults and downtimes is therefore essential, especially with the increasing use of automated operating processes.

Miniature circuit breakers (MCBs) from the SENTRON portfolio

MCBs from the SENTRON portfolio meet the enhanced requirements of automated buildings and industrial power supply systems, e.g. in the automotive and semiconductor industry or in data centers. Compared to residential and functional buildings, these are usually more extensive and complex in terms of both network topology and operation. Electricity and production downtimes must be deliberately prevented in these cases using coordinated device combinations if economic losses are to be avoided. Our MCBs protect wires and cables in cases of short circuit and overloads, and also enable backup protection for switching devices and also semiconductor protection. They are therefore a fundamental component in end-to-end protection concepts for industry and infrastructure.

The right combination

The main purpose of miniature circuit breakers is to permanently monitor and secure cables and wires in electrical systems. They also help protect humans against electric shocks when used in combination with RCCBs or as combined RCBO. Combining the 5SY MCB with the 5SM6 arc-fault detection unit (AFDD) further expands the range of functions. An overview of all the combinations is provided below.

Strengths of the MCBs in the SENTRON portfolio – your benefits

  • Convenient to install and connect
  • Uniform additional components
  • Consistent design
  • Ergonomically formed devices

Better to play it safe

An intelligent, end-to-end protection concept for an electrical system can guarantee reliable protection for humans, your assets and the system itself. We help you to implement all-round protection and standard-compliant solutions easily, quickly and in line with your needs throughout all stages of your value-added process. Find out more here.

Find out more about the SENTRON protection concept

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The right solution for every requirement

Learn, choose, and then order: detailed technical information on miniature circuit breakers in the SENTRON portfolio is available in the Industry Mall. You’re just a few clicks away from your personalized solution for overloads and short circuits.

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