The electron cyclotron resonance heating system is one of the most effective plasma heating systems for controlled nuclear fusion. The key part of the system called gyrotron is driven by a high voltage power supply with a rated output power of hundreds of kilowatts. When the system is in operation, breakdowns frequently occur in the gyrotron. During breakdowns, the gyrotron will endure a large volume of energy and may be damaged. A solid-state switch is required to protect it by blocking high voltage (∼40 kV) within 10 microseconds and limiting energy within a few joules. Compared with Si IGBT/MOSFET, SiC MOSFET with higher switching speed is more suitable for the switch. However, rapid switching speed exacerbates the voltage imbalance. To solve the problems, a reliable module named Advanced Chopper Sub-Model based on SiC MOSFETs for a solid-state switch is proposed. The module adopts a voltage-clamped circuit to achieve the capabilities of rapid switching-off speed, as well as low overvoltage and good voltage balancing. In addition, modules connected in series can tolerate large driver time delay. The SPICE simulation and the double-pulse test are used to validate the effectiveness of the proposed module. The protection performance test was also conducted by using a spark gap to simulate the breakdown fault. Finally, the switch that consists of 64 series-connected modules has been tested at 30 kV/6 A. The turn-off time is ∼5 µs, and the energy during the turn-off transition is 0.283 J. The results show that the switch has good performance.