Cryogenic Submerged Motor


We have developed a range of technologies for special-purpose motors based on a long history of research and development in the following areas.

  • ▸ Insulation systems for motors used in cryogenic conditions
  • ▸ Refrigerant-resistant insulation systems for motors for CFC liquefied gases
  • ▸ Cryogenic-resistant insulation for super-conducting coils

We have a well-established position in the market for motors for use with cryogenic liquefied gases such as those in LNG pumps. Its first products based on the technologies above were launched in 1988, after its 400V class random wound windings and 400V~6600V class formed wound windings had been rigorously tested for cryogenic resistance and their performance verified by quick-cooling heat cycle tests.

Main technical features

Steel Material Use of special steel. Charpy impact test values fall sharply under cryogenic conditions.
Magnet Coil wire Resistant to cryogenic conditions, capable to withstand heat-cycles, and suited to liquefied gas.
Impregnation resin Tensile strength, elasticity and resistance to cracking under cryogenic conditions.
Insulation material Electrical properties, mechanical performance and resistance to cracking under cryogenic conditions.

Main technologies for motors used with cryogenic liquefied gas

Electrical design

Characteristic calculation technology to accommodate conductor resistance and changes in reactance at all cryogenic-liquid temperatures Characteristic calculation technology to accommodate shaft material (magnetic material, non-magnetic material, solid, hollow)

Insulation technology

Refrigerant-resistant (R123. R134a) insulation technology cryogenic insulation technology for super-conducting coils crack-resistant varnish for use in cryogenic conditions

Simulation technology

Simulation of an induction motor under instantaneous voltage drop. Simulation of such as Re-starting during descent of motor revolution for stopping of a pump


Manufacturing technology for small-radius and long motors (manufacture of aluminum rotor)

  • Temperatures of main types of liquefied gas

    LNG(liquefied natural gas) -162℃
    LEG(ethene) -103℃
    Ethane -88.5℃
    Propylene -47.5℃
    LPG(propane) -45℃
    Butane -5℃
    LN2(liquid nitrogen) -196℃

    Structure of cryogenic submerged motor

  • Motor in an in-tanktype cryogenic submerged pump

Standard Specifiactions

Output LOW voltage 0.75kW~500kW
High voltage 75kW~2000kW
Number of poles#1 2P
Speed (synchronous) 3000rpm 3600rpm
Rated voltage / rated
Low voltage 400V/50Hz 440V/60Hz
High voltage 3000, 3300V/50Hz 3300V/60Hz
6000, 6600V/50Hz 6600V/60Hz
Insulation class F
Time rating Continuous
Liquids#3 LNG. LEG. Ethane. Propylene. LPG. Butane. LN2
Starting method Direct-On-Line
Standards JIS. JEM. JEC. IEC
  • #1 Can accommodate other numbers of poles (4P, 6P, etc.)
  • #2 Can accommodate other voltages (380V, 460V, 4160V, 6300 V, etc.)
  • #3 Can be used with liquids other than those listed