Power & Electricals

VPI Dry Type Transformers from Prima [July 2012]


Prima transformers Pvt Ltd is one of the leading manufacturer of dry type distribution transformer, power transformer, control transformer, isolation transformers, ultra isolation transformer, auto transformer, line /load reactors, current transformers, potential transformers, and servo stabiliser. Prima is an ISO 9001-2008 company and has CE approval too.

In the professional journey of two decades, Prima has expanded to match global vision and progressed forward steadily through up-gradation of technology and consolidation programs to further strengthen its capabilities.

Innovation and forward thinking are key words in business enterprises that is why Prima has chosen the demanding area of industrial transformers, an area where challenges are many and solutions difficult.

Vacuum Pressure Impregnated (VPI) Dry Type Transformers

Standards: BIS / IEC / ANSI C57.12.01 /IEEE & IS 1117
Rating: Up to 1250KVA
Voltage Class: 11 KV
Frequency: 50 Hz.
Insulation Class: Class ‘F’ / Class ‘H’ /Class ‘C’
Winding Material: Electrolytic Copper/aluminium
Indoor or Outdoor application
Tap Types: Off Circuit Tap Links / On Load Tap Changer
Enclosure Protection: IP21 / IP33 / IP43 /IP00 & Non ventilated
Termination: Bus Bars (Standard), Cable Boxes (on request)
Cooling: AN (Neutral) / AF (Forced)

Salient Features
• High Dynamic Short Circuit & Mechanical Strength
•  Good Impulse Withstand Strength
• Low Partial Discharge- VPI process ensures void free insulation system
•  Resistance to Temperature Fluctuations
•  Moisture ingress resistant & immune to polluted atmosphere
•  Ease of maintenance
•  Environment friendly

• These transformers are safe, eco-friendly, fire-resistant, explosion proof, easy to install and easy to maintain beside being better in appearance
• Moisture ingress resistant and immune to polluted atmosphere
• Resistance to temperature fluctuations
• Good impulse withstand strength
• High dynamic short circuit and mechanical strength
• Less space and civil work needed
• Special safety features are not required
• Longer transformer life due to low thermal and dielectric ageing.

Comparison between VPI Dry Type & Resin Encapsulated Dry Type Transformers

VPI Dry type Transformer Resin Encapsulated Transformer
Zeroing corona generation is possible so to enable the transformer, not to fail prematurely  Zeroing corona generation is not possible, causing failure in coils during operation.
Economic to repair, since part of coil & copper can be easily replaced /retrieved.  Impossible to repair the transformer, since recovery of copper & lamination not possible 
The VPI /Epoxy shielded design has benefits of unequal environmental protection, high impulse level, low sound & superior short circuit strength.   Cracking of epoxy mould due to thermal cycling. 
Less weight ,smaller dimension for easier handling & installation, fire resistance & no bursting of Tank  Heavier in weight, bigger dimensions hence, difficult in handling & installation. 
VPI / Epoxy shield transformer are maintenance free  Less resistance to cracking, hence regular maintenance required. 

Prima Transformers Pvt Ltd
Kothari Cross Road,
Santej, Tal: Kalol,
Dist: Gandhinagar,
Gujarat - 382721
Tel: + 91 - 2764 - 286115
Fax: + 91 - 2764 – 286645

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