Dry-Type Transformer
A transformer using air or solid insulation instead of liquid, ideal for indoor applications with fire safety priority.
A dry-type transformer uses air or solid insulation instead of liquid dielectric. Preferred indoors where fire safety makes oil-filled transformers impractical.
Types: VPI (Vacuum Pressure Impregnated) and cast resin encapsulated. VPI uses Class H/C insulation with Nomex. Cast resin uses Class F epoxy.
Advantages: no fire hazard, no containment, minimal maintenance. Max ~3,150 kVA, indoor only.
QDTB offers VPI and cast resin transformers from 30-3,150 kVA per IEC 60076-11 and IEEE C57.
Related Products
Related Terms
Cast Resin Dry-Type Transformer
A dry-type transformer with windings encapsulated in epoxy resin for fire safety and moisture resistance indoors.
Insulation Class (A/E/B/F/H)
Standardized temperature ratings for transformer insulation materials defining maximum operating temperatures.
Distribution Transformer
A transformer stepping down voltage from the distribution network (11-33 kV) to utilization voltage (400/230V) for end consumers.
More Terms Starting with “D”
Distribution Transformer
A transformer stepping down voltage from the distribution network (11-33 kV) to utilization voltage (400/230V) for end consumers.
Dissolved Gas Analysis (DGA)
A diagnostic technique analyzing gases dissolved in transformer oil to detect internal faults before they become critical.
Dielectric Strength
The maximum electric field an insulating material can withstand before breakdown, measured in kV/mm.
More in “Transformer Types”
Autotransformer
A transformer with a single winding acting as both primary and secondary, providing voltage conversion through electromagnetic induction and direct electrical connection.
Amorphous Alloy Transformer
A distribution transformer using amorphous metal core material achieving 60-70% lower no-load losses than conventional silicon steel cores.
Box-Type Substation (Prefabricated)
A factory-assembled compact substation integrating transformer, HV/LV switchgear, and protection in a weatherproof enclosure.
Frequently Asked Questions
What is the difference between dry-type and oil-immersed transformers?
A dry-type transformer needs no insulating liquid: the winding is either cast in epoxy resin or vacuum-pressure impregnated and cooled by air. That removes fire load and oil containment, so it can be installed inside occupied buildings such as hospitals, data centres and shopping centres. Oil-immersed units remain the better choice outdoors and for large utility ratings.
Which dry-type transformer is better — cast resin or VPI?
Cast resin windings are encapsulated in epoxy, giving high moisture and pollution resistance with very low maintenance, which suits humid or dirty environments. VPI (vacuum pressure impregnated) open-wound windings with Class H insulation dissipate heat better and cost less, which suits well-ventilated indoor rooms and higher overload duty.
What ratings and standards do QDTB dry-type transformers cover?
QDTB supplies cast resin and VPI dry-type transformers from 30 kVA to 3,300 kVA up to 35 kV, in IP00 to IP54 enclosures, built and tested to IEC 60076-11 and GB/T 1094.11, with CE marking and IEEE/ANSI options on request.
Need help with transformer selection?
QDTB engineers can help you choose the right equipment based on your specific requirements