What is the appropriate slot fullness for motor windings? How much does it relate to temperature rise?

Motor winding slot full rate from the operational level, the lower the slot full rate, embedded wire craftsmanship to be better, whether from the electromagnetic wire into the slot craftsmanship or shaping process, are relatively easy; but from the perspective of the motor winding heat dissipation analysis, the slot full rate is lower when the motor winding temperature rise will be seriously affected.

Enclosed low-voltage motor stator copper wire heat is first conducted to the teeth of the core, slot insulation thickness and thermal conductivity, slot insulation and copper wire and the core of the conductive thermal resistance between the winding temperature rise has a great impact.

The process of dipping and drying the windings is to fill the gaps in the windings to the maximum extent possible by means of insulating varnish, and then to make them into a solid whole by means of the drying process.

If the motor winding slot full rate is too low, dip paint quality is not very good, the winding electromagnetic wire, insulation materials, as well as between them and the core of the gap, small holes, not by the better thermal conductivity of the paint base is fully filled, the winding temperature rise will rise. At present, most manufacturers use VPI vacuum pressure paint immersion process, which can effectively improve the filling effect of insulating varnish, but the relatively loose physical space is also difficult to ensure the effective fixation of the paint base.

For high-voltage motor coils, if the mica tape is not wrapped tightly, the compression is not enough during hot-press curing, or the gap between the coil and the core groove is large, the heat is not easy to dissipate. Taking measures to fill the excess gap during the embedding process of high voltage motor windings is necessary to control the temperature rise of the motor.

The heat of the core and the winding, some or all of the heat is dissipated by the surface of the seat through the contact surface of the core and the seat. The different fit tolerances of the outer circle of the core and the seat and the surface roughness of the mating surfaces can lead to a large variability in the temperature rise of the windings of an enclosed motor. In order to maintain a proper fit interference, the tolerance of the inner diameter of the seat, the tolerance of the outer diameter of the core and the neatness of the outer circle should be strictly controlled. With radial ventilation channel motors, a portion of the heat in the linear portion of the winding is dissipated through the core in the cooling air of the ventilation slots. Core stacking is not tight, punching piece of paint film is too thick, will make the core of the axial thermal conductivity reduction, winding and core temperature rise slightly higher.

In the actual production and processing, especially the insulation treatment of the winding link, some manufacturers do a good job, but there are also manufacturers in the process control of the process is poorly executed, such as VPI equipment sealing effect is not good, the viscosity of the lacquer does not comply with the coil wrapping loose and messy and so on, are some of the commonplace problems.

From the perspective of parts processing control, especially for the winding, core and base, very smooth core can reduce the difficulty of embedded wire, so that the slot fullness of the winding can be higher; embedded wire process, the electromagnetic wire straightened out, the slot will be less irregular pores, which will help the penetration of the lacquer base, in addition to the process of dipping and baking in the process of core preheating and drying process control on the insulating varnish retention is also particularly critical.

Here also want to especially emphasize, slot full rate in addition to the winding temperature rise, there is a more critical impact, is for the utilization of motor materials, relatively appropriate slot full rate can effectively improve the proportion of effective materials, reduce the material cost of the motor.