First, the coil insulation material makes a difference, low voltage motors, the coil mainly uses enamelled wire or other simple insulation, such as composite paper, high voltage motors usually use multi-layer insulation structure, such as powdered mica tape, the structure is more complex, higher degree of pressure resistance.

Second, the difference in cooling structure, low-voltage motors mainly use coaxial fan direct cooling, high-voltage motors most with independent radiator, usually two kinds of fans, a set of internal circulation fan, a set of external circulation fan, two sets of fans running at the same time, in the radiator heat exchange will be discharged outside the motor heat.

Thirdly, the bearing structure is different, low voltage motors usually have a set of bearings at the front and rear, while high voltage motors, because of the heavy load, usually there are two sets of bearings at the axial end, and the number of bearings at the non-axial end is determined according to the load situation, and especially large motors will be used in sliding bearings.

(1) High-voltage motors can be made very powerful, up to thousands or even tens of thousands of kilowatts. This is because, in the same output power, high-voltage motor current can be much smaller than the low-voltage motor (basically inversely proportional to the voltage), for example, 500kW, 4-pole motor rated current, the rated voltage of 380V for 900A or so, while the rated voltage of 10kV when only about 30A. So the high voltage motor winding can be used for smaller wire diameter. As a result, the stator copper loss of a high-voltage motor will also be less than that of a low-voltage motor. For larger power motors, the use of low-voltage electricity, but because of the need for thicker wires and need a large area of the stator groove, so that the stator core diameter to do a lot of motor volume will also be very large.

(2) For larger capacity motors, high-voltage motors used in power supply and distribution equipment than the overall investment in low-voltage motors less, and line loss is small, can save a certain amount of power consumption. Especially 10kV high-voltage motors, can be used directly on the network power supply (China’s high-voltage power supply to the user is generally 10kV), so that the investment in power equipment (mainly transformers) will be less, the use of simpler, the failure rate will be less.