A Compact and Customizable Generator Circuit Breaker From Siemens
Siemens has released a compact, customizable circuit breaker for power generation plants. The circuit breaker is suitable for new installations or retrofits, thanks in part to the customizations available.
Siemens is well known around the world for its power infrastructure product line. Recently, Siemens launched a compact and customizable circuit breaker for power generation plants.
Circuit breakers play an important safety role in any electrical circuit. The circuit breaker is responsible for breaking the electrical connection from the supply to the device or load. From high voltage in the thousands of megawatts all the way down to one watt, circuit breakers protect downstream components. Circuit breakers are designed to open an electrical circuit once the current draw through the breaker has reached a specific threshold. This function is similar to a fuse, only a circuit breaker can be reset to be used again.
Siemens HB1-Compact generator circuit breaker. Image used courtesy of Siemens
Circuit breakers are necessary for every electrical circuit but take up a large amount of space, especially circuit breakers that are capable of switching thousands of amps. The new HB1-Compact (HB1-C) is a versatile circuit breaker for power-generating plants. The HB1-C can be adjusted to fit existing busbar mounting hardware, making the HB1-C an excellent choice for retrofitting existing equipment. The integrated main disconnector can be outfitted with earthing switches for the generator or the transformer that typically resides downstream of the circuit breaker.
Most circuit breakers found inside residential or industrial buildings have ratings around 20 or 50 amps, but when sizing a circuit breaker for electrical infrastructure that manages thousands or millions of watts, the ratings are much higher.
The HM1-C has a breaking capacity of 72 kA and up to 6,700 amp rated current with 24 kV nominal voltage. This style of breaker uses a maintenance-free vacuum technology which allows for up to 10,000 CO operating cycles at full current.
There are two main configurations: the I-shape and L-shape, with the L-shape being the most physically compact. Both configurations can be mounted vertically or horizontally. Offering a circuit breaker this configurable and customizable allows designers to make better use of compact spaces within electrical installations, and maintenance staff will be able to retrofit existing installations with the new style circuit breaker.
The HB1-C can be easily retrofitted to existing equipment. Image used courtesy of Siemens
Maintenance-Free Vacuum Switching
When a circuit breaker opens a circuit with thousands of volts, there is a small electrical arc that bridges the contacts. This arc can damage the contacts or cause fires if flammable material is nearby. Other circuit breakers use insulating gas, compressed air, or oil to quench the arc. With the HB1-C, the contacts reside in a vacuum chamber which requires no maintenance or consumable materials. The internal design of the circuit breaker requires no re-lubrication or adjustment of the springs, making the HB1-C maintenance-free.
Power Generation Applications
High-voltage circuit breakers need to be able to break thousands of amps safely—the components within these circuit breakers eventually wear out and the breaker needs to be replaced. This is the case with the Manitoba, Canada hydropower generating station where 12 circuit breakers will be replaced with the new HB1-C.
The customization of these circuit breakers allows the power plant to replace larger, bulker equipment with smaller, compact circuit breakers. Replacing a large circuit breaker can be quite costly due to transportation costs and outage times. With the HB1-C being compact in size, the transport costs are greatly reduced, and with the customizations, available outages can be reduced.