Dry Type Transformer
- 1. Name :- Smit Shah -140410109096 T.Y Electrical 2 Sem 6 Subject:-Design of DC Machine & Transformer Topic :-Dry Type Transformer 1
- 2. Introduction • Dry type transformers require minimum maintenance to provide many years of reliable trouble free service. A dry-type transformer has no moving parts and is a completely static solid state device, under normal operating conditions, are usually insure a long and trouble-free life. Unlike liquid fill transformers which are cooled with oil or fire resistant liquid dielectric, dry type units utilize only environmentally safe, CSA and UL recognized high temperature insulation systems. 2
- 3. • Dry type transformers provide a safe and reliable power source which does not require fire proof vaults, catch basins or the venting of toxic gasses. These important safety factors allow the installation of dry type transformers inside buildings close to the load, which improves overall system regulation and reduces costly secondary line losses. 3
- 4. • Fire-resistant dry type or "cast resin" transformers are well suited for installation in high-rise buildings, hospitals, underground tunnels, school, steel factories, chemical plants and places where fire safety is a great concern. Hazard free to the environment, dry type transformers have over the years proven to be highly reliable. “Dry type” simply means it is cooled by normal air ventilation. 4
- 5. • The dry type transformer does not require a liquid such as oil or silicone or any other liquid to cool the electrical core and coils. Dry type transformers are voltage changing (Step-up or Step-down) or isolation device that is air cooled rather than liquid cooled. The transformer case is ventilated to allow air to flow and cool the coil (coils). 5
- 6. • Dry type transformers differ from liquid-filled units in many ways, and separate industry standards apply to their design, construction, and maintenance. Dry- Type Transformers suitable for indoor and outdoor applications anywhere that safe and dependable power are important. Cooling ducts in the windings allow heat to be dissipated into the air. 6
- 7. What is Dry Type Transformer? • Dry type transformer never uses any insulating liquid where its winding with core be immerged. Rather windings with core are kept within a sealed tank that is pressurized with air. 7
- 8. Type of Dry Type Transformer • Cast Resin Dry Type Transformer ( CRT) • Vacuum pressure Impregnated Transformer ( VPI) 8
- 9. Cast Resin Dry Type Transformer (CRT) • 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 resin. This encapsulation helps to prevent moisture to penetrate to affect the winding material. 9
- 10. • Complete protection is achieved by this cast resin encapsulation so that the transformer can work without disruption in highly moisture prone area. Thus this transformer is non hygroscopic. This type of transformer is available in ratings of 25 KVA to 12,500 KVA. with insulation class of F (90°C Temp. Rise). 10
- 11. 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 foil or strip in a continuous layer. But 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. 11
- 12. • 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. This type of transformer is available from 5 KVA to 30MVA with insulation grade F(155oC) and H(180oC). It’s with Protection up to IP56 . 12
- 13. 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 heating. • Suited for damp and contaminated areas. 13
- 14. Disadvantages of Dry Type Transformer • Dry type transformer is long lasting and with less chance of winding failure. But once it fails whole set up is to changed, i.e. complete change of high voltage and low voltage winding with limb. • For same power and voltage rating, dry type transformer is costlier than oil cooled transformer. 14
- 15. 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 (e.g. off-shore wind turbines) 15
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