A Transformer is a static piece of apparatus used for transferring power from one circuit to another without change in frequency. It can raise or lower the voltage with a corresponding decrease or increase in current.
The basic principle of a transformer is Faraday’s Law of Electromagnetic induction, which states that whenever the flux linked with a coil changes an e.m.f is induced, the transformer consists of a laminated iron core(Cold Rolled Grain Oriented Core Lamination) about which are wound two or more sets of windings, voltage is applied to one set of windings, called the primary, which builds up a magnetic flux through the iron. This flux generates a counter e.m.f. in the secondary which limits the current down from the supply.
Makpower transformers are designed and tested as per national & international standards i.e. IS : 2026, IS : 1180, IEC 76, BSI 171, ASA C57 and other relevant IS & IE rules.
Windings:
The most critical component of the transformer is the windings. MAKPOWER uses Electrolytic grade high conductivity Copper / Aluminium conductors duly insulated with paper/nomex/glass for the windings according to the application and technical specification of the transformers.
MAKPOWER makes sure that not even a single brazing is used during the making of the windings, to ensure low losses of the transformer. The wound coils are pressed, clamped and dried in oven prior to Core Coil Assembly for better Short Circuit withstanding ability during fault conditions.
To reduce hot spots and keep the windings cool, cooling ducts are formed with rigid, high density spacers and horizontal and vertical ducts are provided.
Core Construction:
Our Iron core has exceptionally low level noise, no load losses and good flux distribution at the joints which is achieved by using high grade, high permeability and cold-rolled grain oriented (CRGO) silicon steel laminations.
Laminations are burr free and very thin between 0.23mm and 0.30mm, varying no more than +0.05mm in length for the lowest sound level and excitation currents. Each lamination is covered with a high-resistance, inorganic coating to reduce eddy currents.
Cooling ducts are provided in large transformers for efficient circulation of oil to maintain the core temperature without affecting the flux distortion.
Core & Coil Assembly:
Makpower uses high electrical grade Kraft Paper & Press Board, as per IS: 1576. The Insulating papers are checked for high dielectric strength, good ageing properties and moisture retardation. Permali wood is also used in top and bottom for mechanical strength. Well profiled angled rings are placed between LV & HV windings to reduce voltage stress level. The ends & tapping leads of all windings are connected by special extra flexible, insulated copper cables which are rigidly braced in position.
We maintain an intensive quality control process due to which Core-Coil assembly of our transformer can withstand tremendous electromechanical stress for a long life span. This is the result of our meticulous workmanship and sturdy design that we have successfully type tested upto 2500 KVA, 33 KV, Transformer at ERDA.
Tank and Fittings:
Makpower transformer tank consists of robust construction consisting of adequate wall and base thickness with proper reinforcement to ensure no bulging occurs during transformer’s long life span. High grade tested mild steel are used for tank fabrication.
Every tank undergoes intensive pressure and vacuum tests of 0.5 KG/cm2 or above to ensure no oil leakage in the tank.
High quality fittings and accessories are sourced from leading suppliers for use in our transformers as per relevant IS and IEC standards. Flat gasket of neoprene bonded cork sheets are used for joints and auxiliary fitments.
Painting/Finishing:
Prevention of corrosion is very important to us so All fabricated steel tanks are internally & externally cleaned thoroughly of all scales & rust by sand blasting. A coat of hot oil yellow paint is immediately applied to all internal surfaces. This anticorrosive paint has rust inhibitive properties and excellent chemical resistance. Two coats of glossy, oil & weather resisting, not fading paint and one coat of primer of light grey, Shade No. 631 of ISS are then applied.
Transformer Oil:
The insulating oil used is of low viscosity with good resistance to oxidation and formation of sludge and acids. Moisture content, dielectric strength etc is determined and certified by conduct relevant testes as per IS-335/ 1993. Generally we use ‘TRANSOL’ make EHV grade Oil.
Testing:
Makpower dispatches the transformers to our customers only after successfully passing intensive final inspection and testing process. This process ensures that our customers will receive a safe and reliable transformer. Our testing Lab is fully equipped with 180KV High Voltage Test Set, Double Frequency Test Set (Upto 30 MVA, 132 KV), CT’s & PT’s to check Losses & Impedence, 3 phase Variac for Power supply, Resistance meter, 3 phase Ratio meter in addition to other normal testing instruments.
We perform routines tests on all units manufactured in accordance with IS 2026 standards.
Measurement of winding resistance
Measurement of voltage ratio and check of phase displacement
Measurement of short-circuit impedance and load loss
Measurement of no-load loss and current
Dielectric tests
Tests on on-load tap-changers
We also perform some type and special tests such as temperature rise test and magnetic balance test upon customer request. Impulse test and short circuit rest has been carried out on some of our transformers in ERDA, Vadodara.
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