DRY TYPE Transformer — VPI & CRT
The dry type transformer is of two types. They are:
- Cast Resin Dry Type Transformer ( CRT) .
- Vacuum pressure Impregnated Transformer ( VPI) .
Cast Resin Dry Type Transformer
Cast resin dry type transformer (CRT) is used in the high moisture prone areas. It is because of its primary and secondary windings are encapsulated with epoxy res-in. This encapsulation helps to prevent moisture to pene-trate to affect the winding material. Complete protection is achieved by this cast resin encapsulation so that the transformer can work without disruption in highly mois-ture prone area. Thus this transformer is non hygroscop-ic. This type of transformer is available in ratings of 1 KVA to 1600 KVA. with insulation class of F & H .
Vacuum Pressure Impregnated Transformer (VPI)
This type of transformer is made with minimum flammable material as insulation of windings. The windings of this transformer are made in strip in a continuous layer.
For higher voltages, the winding is made of disks that are connected in series or parallel as per power rating with respect to voltage level. The insulation of the winding is void free impregnation that is made with class H polyester resin. The primary and secondary winding with core are laced safely within a vacuum protective box. Moisture Ingress Protection is high and it never gets affected by moisture.
Advantages of Dry Type Transformer:-
- Safety for people and property.
- Maintenance and pollution free solution.
- Easy installation.
- Side clearance is less.
- Environmentally friendly.
- Excellent capacity to support overloads.
- Reduced cost on civil installation works and fire protection systems.
- Excellent performance in case of seismic events.
- No fire hazard.
- Excellent resistance to short circuit currents.
- Long lasting due to low thermal and dielectric
- Suited for damp and contaminated areas.
Application of Dry Type Transformer:-
- Chemical, oil and gas industry
- Environmentally sensitive areas (e.g. water protection areas)
- Fire-risk areas (e.g. forests)
- Inner-city substations
- Indoor and underground substations
- Renewable generation
This type of transformer is used in applications where the transformer is to be installed in harsh climatic conditions (smoke, pollution, dusty environment,etc.) or if the transformer is KNAN cooling type.
Auto Transformer
An autotransformer (sometimes called auto step down transformer) is an electrical transformer with only one winding. In an autotransformer, portions of the same winding act as both the primary and secondary sides of the transformer.
lightening transformers
Electrically isolating of the lighting load from main load. Better control on protection systems due to separation of neutral of lighting load & main load