Inside Our Vacuum Drying & Impregnation Process
2026-06-15
Vacuum drying and impregnation is one of the most decisive steps in building a
reliable power capacitor. It removes moisture and air from the wound element and
replaces them with impregnant, eliminating the voids where partial discharge —
and eventual failure — begins.
Why it matters
- Moisture is the enemy. Even trace water raises dielectric loss (tan δ) and
accelerates ageing under voltage stress. - Voids cause partial discharge. Air pockets inside the dielectric ionise
under high field strength, eroding the film over time. - Full impregnation stabilises capacitance and improves thermal transfer,
which is critical for continuous high-frequency duty.
How we control it
- Vacuum drying — elements are held under heat and vacuum to drive off
moisture before any impregnant is introduced. - Degassed impregnation — the impregnant is itself degassed, then drawn into
the element under vacuum so it reaches every layer. - Pressure soak — pressure is applied to ensure complete penetration and to
collapse any remaining voids. - Verification — tan δ and capacitance are measured after processing and
recorded as part of each unit's factory acceptance test.
The result is a capacitor with low losses, stable parameters, and a service life
that holds up under demanding industrial cycles.