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Pure Water Vaporization-cooling Silicon Rectifier


  • Pure water vaporization natural cooling
    This epoch-making natural vaporization-cooling rectifier uses pure water for the coolant. There is no impact at all on the Earth's environment.
  • Japan's largest silicon rectifier diode
    We developed this high-voltage, large-capacity silicon rectifier diode based on our many years of experience and technology in power semiconductors. We have achieved a product with a significantly reduced number of parts, that is compact and lightweight, and features high efficiency. Reduction rates: 40 % volume, 30 % floor space, 40 % mass, 40 % losses. (Reduction rates are in comparison with our 6,000 kW PFC vaporization-cooling rectifier.)
  • Fine ceramics insulation
    The use of fine ceramics with high thermal conductivity and high insulation on both sides of the cooling body insulates the silicon rectifier diode and the main circuit conductor enabling the entire unit to have ground potential.
  • Completely sealed structure
    We have achieved a completely sealed structure that uses vaporization cooling such as for the snubber and surge absorber resistors, and reduces the temperature rise in the stack storage unit.

Cooling principle

The heat generated by the silicon rectifier diode vaporizes the pure water inside the cooling body. At that time, the large latent heat of vaporization efficiently cools the silicon rectifier diode. The water vapor is cooled in the condenser and returns to the cooling body to become a liquid again. Note that the vessel is under constant negative pressure.

Silicon rectifier diode

Type ER3211FL-50
Repetitive peak reverse voltage 5000 V
Non-repetitive peak reverse voltage 5500 V
Average forward current
(50 Hz sine wave, conduction angle 180°)
3200 A
Surge current
(50 Hz sine half-wave, 1 cycle, from rated load condition)
58000 A
External diameter φ125 mm

Internal structure

Standard specifications

Name Pure water vaporization-cooling silicon rectifier
Installed location Indoors or outdoors
Ambient air temperature *1 0 to +40˚C,ー5 to +40˚C,ー10 to +40˚C
Cooling method Vaporization natural cooling
Applicable standard JECー2410 (1998)
Frequency 50 Hz or 60 Hz
Rated class D or E
Type of connection Three-phase bridge (6-pulse), or double three-phase bridge (parallel 12-pulse) *2
DC voltage 1500, 750, 600 V
Standard output Rated output
DC voltage [V]
1500 750 600
DC voltage fluctuation rate 6% or 8%
Auxiliary power source Control circuit: 100/110 V DC
Space heater circuit: Single-phase 200 V AC, 600 W
Paint color Munsell 5Y7 / 1
*1: Minimum ambient air temperatures of -5°C and -10°C are for variable conductance. *2: Better than three-phase bridge series (series 12-pulse) in all respects: dimensions, mass and efficiency. Interphase reactor is not required.


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