Siemens’ 120 V Solid-state Circuit Breaker Now UL Listed

October 12, 2022 by Shawn Dietrich

Siemens breaks new ground by having a solid-state circuit breaker UL listed for residential, commercial, and light industrial use.

The 120 V, single pole solid-state circuit breaker from Siemens' is the first of its kind to receive a UL listing. This achievement opens up new possibilities for the features and capabilities of solid state circuit breakers to be used in residential, commericial, and light applications.


Siemens' UL-listed 120 V Solid-state Circuit Breaker

Siemens’ 120 V solid-state circuit breaker now UL listed. Image used courtesy of Siemens


What are Circuit Breakers?

Circuit breakers can be found in residential settings, commercial buildings, and factory floors. A circuit breaker's purpose is to break the circuit when unsafe current levels are reached. Circuit breakers are similar to fuses, except that a circuit breaker can be reset and a fuse cannot.

All circuit breakers that are in use must be UL certified—this certification ensures technicians and end-users that the appliance will work as expected and is safe for electrical use. Up until Siemens 120 V solid-state circuit breaker received a UL listing, all UL-certified circuit breakers were made with moving parts; bimetal strips or electro-magnets would draw contacts away from each other as the current in the circuit rises. 


solid-state circuit breakers interrupt and electrical circuit

Solid-state circuit breakers use advanced software algorithms and semiconductors to interrupt an electrical circuit. Image used courtesy of Troy Bridges


Solid-State Circuit Breakers

A solid-state circuit breaker interrupts an electrical circuit using advanced software algorithms and semiconductors—the reason this is important is because of arc flash. When a circuit breaker detects a short circuit (no load on the circuit), a large amount of current arches across the internal contacts of the circuit breaker. In some situations, this can cause a fire or explosion—it’s the equivalent of lighting a lighter in a hazardous location. 

A solid-state circuit breaker can be a safer option. With the solid-state circuit breaker not having any moving parts, it can perform the action of an electromechanical circuit breaker faster and more efficiently. Software-driven components mean more control over the device and better monitoring of current spikes.

When large amounts for current travel through metal, there is heat dissipation that occurs. With the solid-state technology, there is no heat generation, in fact, this technology is the first UL-certified circuit breaker that operates with passive heat management. These circuit breakers will not be required to have specific airflow and can be installed in standard electrical panels


What is UL Certification?

In order for electrical components to be installed in residential, commercial, or industrial environments, they must be UL certified. The UL certification means that the device has been tested and will perform as expected. UL certified is an umbrella term for UL listed and UL recognized—UL listing is for a "stand-alone" part, and UL recognized is for a part that is in a larger component.

The solid-state technology from Siemens that has receivied UL listing is a single pole, 120 VAC solid-state circuit breaker. This technology can monitor one circuit of 120 VAC and interrupt that circuit if the current rises over its rate current or if there is a short circuit detected. 


software and semiconductors to control circuits

The use of software and semiconductors to control circuits opens doors to a plethora of automation solutions. Image used courtesy of Markus Spiske


Future Use

Using software and semiconductors to control circuits opens doors to automation solutions that were not possible before. If these circuit breakers can be connected to an industrial network, we can capture current consumption on each circuit and know when breakers have tripped and at what current they tripped at. 

Combining this technology with IIoT can alert maintenance personnel when electrical circuits are drawing more current than they should be or inform process engineers that a process is not performing as it should simply by the spike in current draw. While there are already some devices on the market that perform these tasks individually, combining these features within a circuit breaker reduces total component and installation costs. 

1 Comment
  • N
    nfrihart October 13, 2022

    Looks like a fantastic product, would like to see the time current curves, what product series name has Siemens given to this product? Is it suitable for classified locations?

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