Epoxy VPI System Vacuum Levels
Epoxy VPI System Vacuum Levels
(OP)
In regard to form wound induction motors, are there any drawbacks to drawing a higher than recommended vacuum(recommended by the VPI equipment manufacturer)? For example a recommended vacuum level of 3 torr is typical for using epoxy resin. Is going to less than 1 Torr going to cause any problems? Will it really help in getting better impregnation of the coils?





RE: Epoxy VPI System Vacuum Levels
RE: Epoxy VPI System Vacuum Levels
RE: Epoxy VPI System Vacuum Levels
That being said, your specification should be based on establishing reliable varnish penetration for the different voltage coils that you handle (2300V, 4000V, 6600V) based on the different types and/or different layers of insulation that are required for each voltage. Treating sample coils, as described by motorwinder, is the only way to know that your process times are good.
That being said, keep in mind that 'sample coils' are typically placed in a fixture that clamps them between plates of steel (or some other hard impermeable substance) to simulate being installed in a stator slot.
Finally, I would agree with Motorwinder that the pressure cycle is more important to penetration than the vacuum cycle. However, that may be dependent on the varnish type that you are using. Again, I would say that the varnish manufacturer should be the definitive source for determining your cycle times.