• Insulating materials and their properties
• Ageing of insulation
• Practices of insulation systems
• Procedure for vacuum pressure impregnation
• Maintenance of insulation
• Monitoring the quality of insulation of MV formed coils and resin-poorwindings during manufacturing

Insulating materials and their properties
The insulating materials form the heart of an electrical machine. During operation these materials may be subject to electrical, thermal and mechanical stresses and
must be capable to endure the same and possess the following,
Electrical stresses

• high breakdown voltage
• good long time performance
• low partial discharges (minimum voids within insulation or on interface between insulation systems)
• very small leakage or creepage currents.

Thermal stresses

• high long time performance
• small deformation after temperature cycles
• least delamination within insulation material

Mechanical stresses

• high mechanical strength to sustain forces due to handling and mechanical forces under operation.

least reduction of mechanical strength within specified operating temperature and voltage.