Protection against short-circuit situations and power overload within μs
The primary and most important function of the Astrol solid-state DC breaker technology is its ultra-fast interruption of high powers, thereby preventing the dramatic consequences of short-circuit situations.
Our ultra-fast series of water-cooled DC breakers for the maritime industry are available in three different sizes with a rated voltage of 1.5kV and a rated current between 500A and 3000A. All variants are DNV and CCS certified.
Lifetime in line with complete drive system
The design of our DC breaker switches is based upon market input. One of the design milestones dictated by the industry was a product lifetime of at least 15 years. This is achieved by adding sufficient redundancy. Thereby the lifetime of our solid-state breakers even exceeds the standard lifetime of a typical drive system. No maintenance is needed. The redundancy also leads to an extra robust system. This is shown in the extremely high number of short-circuit and switching-off (fault) conditions without showing any degradation. In short: we developed a maintenance free, robust and reliable solid-state DC breaker switch.
Best in category di/dt capability allowing ultra-fast switch-off
The IGBT technology in combination with MOV guarantees ultra-fast swith-off times. A short-circuit is detected within 2µs, and IGBT switch-off takes less than 4µs. The DC Breaker is able to detect, clear and separate short-circuits from healthy system parts before they reach dangerous levels. Depending on the rating of the DC breaker and inductance of the system a total clearing time of 10 – 21 microseconds is feasible.
For a typical inductance of 4 μH:
- Breaking time: 8 μs
- Clearance time: 7 - 13.4 μs
Stand-alone solution for integration in any type of DC grid
The Astrol DC Breaker is system independent and can be integrated in any type of DC distribution grid. It constantly monitors current and voltage on the DC bus and reacts autonomously according to predefined settings. Protection functions include protection against short-circuits and power overloads. Internal self-diagnostics constantly monitors the health state of the internal breaker functions and reports irregularities to the overall controller.
Every solid-state breaker has a slightly increased conduction loss compared to mechanical breakers, caused by the inevitable resistance of the semiconductor. However, the switching speed and the elimination of moving parts allow for optimized system designs and provide large saving potential in both, operation and maintenance.
Well-designed over-dimensioning of the IGBTs inside the breaker reduces the electric resistance to a minimum, and in addition adds redundancy on the semiconductor level. The power losses strongly depend on the current profile in the application. In any case, the DC-Breaker achieves efficiency levels of 99% or even higher.
Compact Mechanical design
The compact mechanical design supports the control concept of the DC breaker to work as a standalone solution. The isolating fiberglass housing allows easy integration in a cabinet, but also the installation without cabinet. With its modular build-up, the focus lies on standardized power modules, which combine to different voltage and current ratings with minimal mechanical changes. The power modules are accessible from the front and the backside. All components are UL94 certified and vibration tested according to IEC 60068-2-6.
Electrical design / topology
An optimized topology reduces the temperature cycles of the semiconductor modules. This leads to a longer useful life of the IGBT's and reduces system maintenance. Due to the ultrafast detection and switching time, the DC Breaker can safely control low system inductance without adding more inductance to the circuit. With the Astrol DC breaker, the system integrator enjoys maximum design freedom.
The controller of the breaker and the direct optical link between several breakers manage short circuit protection of healthy zones without protocol overhead.
For switching actions controlled by the overall system controller, the DC breakers provides different communication interfaces:
- Optical (Glass or Plastic)
- Modbus-TCP , Profinet , WEB based
- Wire Bus System with CAN and RS485
- 24V power supply with internal filter module
Parametrization and Customization
The DC-Breakers provides application specific parametrization. Short circuit and over current detection can be adjusted according to customer specific requirements. Different parameter settings do not require re-certification. A customized DC breaker can either be an adapted standard of a certified version or a completely new version.
Typical items for customization are:
- Communication to overall controller
- Internal or external cooling
- Quick coupling connectors in the water cooling circuit
- External fan control with PMW
When the bus tie breaker is open, the capacitors on each side of the breaker can be charged to different voltage levels. The closing of the bus tie will cause an inrush current, which will immediately trigger the short circuit detection of the DC-Breaker. To solve this problem, the Balancing Switch option is available in connection with every Astrol DC breaker. The Balancing Switch is an IGBT controlled pre-charge device, which assures voltage balancing of inside the circuit and smooth closing of the DC breaker.
All versions have been certified by DNV and CCS.
- small model 1.5kV - 350-500A several variants
- medium model 1.5kV - 1.1-1.5kA sevaral variants
- large model 1.5kV - 2.25-3kA several variants
- air-cooled model 1kV - 200A several variants
- > 3kV models upon request
- under development 1.5kV - up to 5kA