Transformers

Power transformers are used to increase voltage levels to enable long-distance electric transmissions without a frequency change. In an electronic system, the term power transformer is used to provide a number of AC supplies of appropriate voltages and values of current from a public electricity supply.

Advantages

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Key Features

Designed for 25 years of trouble-free performance
Design conforms to IS 2026, BS 171, IEC 76, and other relevant standards
Low power loss and low noise
Designed to withstand electrical impulses, thermal, and dynamic stresses
Optimum utilization of active materials for compactness
High performance with life extension and loading flexibility
Modern manufacturing techniques to ensure cost effectiveness and reliability

Specifications

3 phase, 50Hz in voltages of 11kV, 22kV, 33kV, 66kV, 110kV, and 132kV
Off-circuit tap changer to provide ± 5 %, ± 7.5% & +5% to -10% taps in steps of 2.5%
On-load tap changer to provide standard range of +5% to -15% taps in steps of 1.25%, 1.7%, 10-21 % @@ 1.75%, and can be custom built for any other ranges
OLTC can be internally/externally mounted as per requirement
Class A, uniform/non-uniform insulated
Vector group Dyn 11, YNd 11, YNyn 0
Continuous duty, double copper wound
Painting as per IS/IEC standards
Both HV and LV side outdoor bushings or cable boxes
Cooling radiators/fans
Standard fittings as per IS/IEC standards
Buchholz relay with alarm and trip contact with shut off valves
Oil temperature indicator with alarm and trip contact
Winding temperature indicator with alarm and trip contact
Magnetic oil level gauge with alarm contact
Marshaling box to house oil temperature indicator and winding temperature indicator
Cooler control unit
Neutral current transformer

Manufacturing Process

Winding
All windings are made by experienced and qualified winders with at least 2 years of experience.
Dry type windings are made on fiber glass mandrels to ensure that there is no inadvertent tearing of the insulations.
All windings are designed to withstand short circuits and minimize copper usage.
Windings are made using either copper or aluminum, and can be offered for oil-filled transformers, VPI dry type transformers or cast resin transformers.

Core Assembly
Core used is grain oriented steel, manufactured and designed considering the Step Lap method, including mitred joints.
Using optimal design and manufacturing processes, air gaps are reduced between yokes and legs, reducing noise and losses.
Core is bound and costed with a special resin which further reduces noise and losses.
Core is sourced from quality vendors and processed on automated machines to ensure proper 45 degree edging.
Each core is inspected and losses are measured prior to the next process.

Core Coil Assembly
Windings are taken after consolidation and placed on individual limbs of cores.
Proper insulation scheme, spacers, and routing of cables is ensured.
Reblading, brazing of busbars and final fittings are completed.
Core coil assembly is dried for over 12 hours at up to 105 degrees, until completely dry.
33 kV and above are processed under vacuum.

Final Assembly
Fully dried and consolidated core coils are taken and inserted into tanks.
After tightening, fixing and cover closure, fittings and accessories are mounted.
Tanks are pressure tested for 4 hours in "Hot Oil Condition”.
Transformers are painted and paint thickness is checked and maintained.
Custom painting systems according to customer's requirements are offered in Epoxy, Hot Zinc Spray, Powder Coating and Polyurethane.

Testing & Inspection
All transformers are tested in our Lab according to National and International Standards (IS:2026, IEC 76, etc.)
Voltage ratio
Winding resistance
Impedance voltage
No load and load losses
No load current

Dielectric tests
Noise level measurement
DGA - Dissolved Gas Analysis for testing oil
Harmonic measurement and analysis
Temperature rise test plant
Vacuum and pressure test plant
Oil test facilities

Explore Other UPT Products

To learn more about UPT’s power transformers and other power equipment