Solid-state AC switches

Astrol AC switches: the safe and maintenance-free alternative to mechanical switches

Our solid-state AC-Switches are available in both standardized and customized designs. They are applied in systems where frequent switching of AC-currents is required. The accurate and maintenance-free operation gives it a clear advantage over mechanical switching solutions.

The AC-Switches are available as a 1-phase and 3-phase design, with rated voltages of up to 36kV, water-cooled or air-cooled.
Depending on the requirements, the control logic can include phase angle switching capability, as well as various monitoring functions, such as voltage and current supervision as well as health monitoring. Astrol solid-state AC switches are available as turnkey solutions, including switch controller, monitoring and cooling system.

Main functionalities and specifications

  • Maintenance-free switching of high AC-voltage and currents.
  • Fast and accurate power management by phase angle control.
  • Switch controller including various measurement and supervision functions.
  • Accurate voltage and current measurements to allow system health monitoring over time.
  • Up to 3-phase, 36kV per phase
  • Standardized single-phase version for 27.5 kV railways neutral sections switches
  • Compact design
  • Forced air-cooled or water-cooled options

Main industries and applications

  • Railway industry
    • Neutral section switch in railways Single phase 25kV AC dual switch substations.
    • Maglev railway switch for the sequential switching of linear motors.
  • Renewable energy industry
    • 3-phase AC-switches for heat storage applications.

Application example: Tri-Phase AC Breaker 11kV/400A for railway grid application

In many railway networks, different sections of a railway line are supplied by different phases of the AC grid and therefore need to be isolated from each other. The line section in between two sections with different phases is called neutral section. Often, neutral sections are relatively short and a train can easily coast through them without power supply from the catenary.

However, in some railway networks, especially in China, the neutral sections are longer and sometimes in up-hill sections of the railway line, which makes it impossible for the train to coast through without additional power supply. In such case, the neutral sections need to be electrified. This electrification is traditionally realized by one-phase mechanical switches at each end of the neutral section, which allow the electrification of the neutral section from either side.

High cost of mechanical switches

The problem with such mechanical switches is that due to frequent traffic on the railway line, the power switching frequency is high. In addition, especially in uphill sections, the locomotives are operating at high power, which leads to high currents in the neutral section. Both together, the high switching frequency and the high switching frequency, leads to fast consumption of the electrodes and short maintenance intervals of the mechanical switches are unavoidable. The fact that the switches are often installed in mountainous regions leads to a further increase of the maintenance cost.

Like in many other applications, the answer to this problem is solid-state technology. Just as the traditional mechanical solution, the Astrol solid-state RWS is installed at both ends of the neutral section and allows its electrification from either side. The change-over from Phase A (first side power supply) to Phase B (second side power supply) can be realized seamless within milliseconds, in a way that no interruption of the power during the change-over can be sensed by the train passengers.

The Astrol railway switch is realized as a platform, with customizable current and voltage ratings. It allows every neutral section to be equipped with the optimal amount of power electronics components, but always based on the same qualified power electronics technology.

Typical specifications

  • Rated voltage:   27.5kVAC  50Hz
  • Rated current:   1000A
  • Load profile:       40 seconds on time every 7 minutes
  • Cooling mode:   Air-forced cooling with heat pipes

At Astrol, we are more than just a design partner. With our commitment to quality, innovation, and customer satisfaction, we are your long-term collaborator in success.

Astrol long-term collaborator

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