R AC single/3-phase pure resistance load bank adopts segmented combination control for power input, unified segmented power input, supporting sudden loading/unloading, adopting an energy-consuming working mode for the load, forced air-cooled heat dissipation, greatly ensuring the reliability of constant power discharge. The resistors are independently produced with intellectual property rights, high power density, and no red heat phenomenon. The automatic overheat protection function prevents overheating or burning out even if the fan is not rotating, keeping safety and long service life.