Moisture Content
The amount of water in transformer oil and solid insulation, critical for dielectric strength and insulation life.
Moisture is critical for transformer insulation. Water enters through breathing, leaks, or cellulose degradation. Small amounts dramatically reduce dielectric strength and accelerate aging.
Oil-cellulose equilibrium means paper contains 20-40x more moisture than oil. Paper >5% moisture = problematic. Oil limits: <15 ppm (EHV), <25 ppm (HV).
Effects: reduced dielectric strength, accelerated degradation, increased dissipation factor, enhanced gas in DGA. Measured by Karl Fischer, FDS.
QDTB ensures all transformers ship with moisture well below limits via vapor-phase drying. Proper preservation prevents ingress.
Related Products
Related Terms
Dielectric Strength
The maximum electric field an insulating material can withstand before breakdown, measured in kV/mm.
Insulation Class (A/E/B/F/H)
Standardized temperature ratings for transformer insulation materials defining maximum operating temperatures.
Dissolved Gas Analysis (DGA)
A diagnostic technique analyzing gases dissolved in transformer oil to detect internal faults before they become critical.
Oil-Immersed Transformer
A transformer using mineral oil as insulation and cooling medium, most common for outdoor power and distribution.
More Terms Starting with “M”
Magnetic Core
The laminated silicon steel assembly providing a low-reluctance path for magnetic flux, backbone of transformer operation.
Magnetizing Current
The reactive component of no-load current establishing magnetic flux in the transformer core.
Marshalling Box
External enclosure housing transformer control wiring, terminals, and auxiliary circuits for substation connection.
Magnetic Flux
The total magnetic field passing through the transformer core cross-section, fundamental to electromagnetic energy transfer.
More in “Diagnostics & Maintenance”
Dissolved Gas Analysis (DGA)
A diagnostic technique analyzing gases dissolved in transformer oil to detect internal faults before they become critical.
Furan Analysis
A diagnostic measuring furan compounds in transformer oil to assess cellulose insulation degradation.
Partial Discharge (PD)
Localized electrical discharges in small insulation regions not bridging electrodes, indicating defects or aging.
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