Makpower Transformers Private Limited

The Automatic Step Voltage Regulator (ASVR) are available in three types :

1. If the variation of input high voltage is within 15-20% of the rated voltage; the step-down transformer can be provided with ON LOAD TAP CHANGER (OLTC).The voltage sensing relay of the OLTC panel choose the suitable tap automatically resulting the regulated output voltage.
2. If the variation of input high voltage is more then 20% of the rated voltage, the OLTC is attached with a star connected high voltage auto transformer having suitable taps in addition of normal step down transformer and placed in the same cabinet. The voltage sensing relay of the OLTC panel choose the suitable tap automatically and regulated HT voltage (+1-- 1%) from the auto transformer is fed to the step-down transformer.
3. If normal step-down transformer had already been installed or if the capacity of the step-down transformer is very high (more than 2MVA); the regulator is made in separate cabinet. This type of regulator consists of an auto-transformer with OLTC. Regulated HT voltage from the regulator is fed to the step-down transformer.
   The present product range of MTPL includes ASVRs in 6 KV, 11 KV & 33 KV system and upto 10000 KVA. We also manufacture tailor made equipments as per requirements of our customers.

Major Supplies:

The present product range of MTPL includes ASVRs in 6 KV, 11 KV & 33 KV system and upto 10000 KVA. We also manufacture tailor made equipments as per requirements of our customers.

Small transformers such as 5 KVA, 10 KVA & 16 KVA, single phase Transformers and 16 KVA, 25 KVA, 63 KVA and 100 KVA Three Phase transformers are generally called Rural Electrification (RE) jobs. These transformer are Generally Aluminium wound and without tap switch. We are also manufacturing transformers required under Rajiv Gandhi Gramin Vidyut Yojna (RGGVY) and Accelerated Power Development and Reform Programme (APDRP) scheme.

Details of losses for STAR rated distribution transformers as certified by Bureau of Energy Efficiency (BEE).

The total losses at 50% and 100% shall not exceed the values given below :

Our 25,63 & 100 KVA transformers are impulse tested at Jadavpur University, Kolkata and also short circuit tested at CPRI, Bangalore.

Dry type Transformers are Vacuum Impregnated type with class 'C insulation having allowable temperature 140°C at an Ambient of 40°C. The insulating materials used is Fibre Glass Cylinders and windings having NOMEX insulation with 50:50 overlap. Nomex insulation is having high dielectric strength and is capable to withstand high temperature. The temperature withstanding capacity is aenerally made to comply with IEC 76/IS 2026/IS 11171.

MAJOR SUPPLIES:

Our 11KV 1000 KVA Dry Type Transformer is successfully passed Impulse Test of 75 KVp from Jadavpur University, Kolkata.

The greatest aspect of a furnace transformer is its Electrical Designs. Which need selection of proper conductor size, type of coils used and selection of current density of copper conductor and flux density of CRGO core for better Short Circuit Protection.

Major Supplies :

Apart from above, we have also supplied our Induction Furnace Transformers to M/s. Famous Steel Ltd, Bangladesh, Khadeem Steel Industries, Bangladesh, Nandan Ghar Sansar Developers Ltd, Mujaffarpur, Al-aska Steel Ltd, Bangladesh, Sasco Steel Limited, Makers Castings (India) Pvt. Ltd & La-Opala RG. Limited, etc.

Our 4500 KVA, 33000/ 900-900V Transformer is successfully passed in impulse Test of 250 KVp from I.I.T. Kharagpur.

Our Transformers are installed with furnaces of Inductotherm, Meghatherm, Indotherm, Electrotherm & G.A. Danially.

Electrolytic grade, high conductivity Copper Busbar having current density of 1.6 Amp/sq.mm or Electrolytic E91E grade Aluminum Bubars having current density of 1.0 amp/sq.mm are used in our panels. The Busbars shall be properly covered with Heat shrinkable PVC sleeves and duly colour coded. Necessary FRP supports are also given for Robust construction & to withstand Short circuit conditions.

All the doors, cut-outs for cable entry plates etc. shall have best quality synthetic rubber gaskets without any discontinuity to make the panel completely dust, damp & vermin proof. Necessary pretreatment on the surface of the panel board is carried out prior to powder coating i.e. Degreasing, Derusting, Phosphating and passivation to have a count of 8-10 micron phosphate coat. This is a nine tank hot phosphating process. The panel shall be finished with oven baked Powder coating to shade no. RAL 7032.

Short Circuit Test from CPRI, Bangalore has been done on 5000 Amp. Busbar.

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 principal of a transformer is Faraday's Laws 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.

MTPL 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 :

Electrolytic grade high conductivity Copper / Aluminium duly insulated with paper / nomex / glass is used according to application & technical specification of transformers. For better short circuit ability under fault conditions, wound coils are pressed, clamped and dried in oven prior to impregnation in oil. Cooling ducts formed with rigid, high density spacers and horizontal and vertical ducts are provided to save hot spots.

CORE CONSTRUCTIONS:

The core is designed with optimum flux density to minimize core loss and cost. Butt-lap, miter or step-lap-miter construction is chosen based on the application and core-loss requirements. Laminations are burr free and very thin between 0.23 mm and 0.30 mm, varying no more than ±0.05 mm in length for the lowest sound level and excitation currents. Each lamination is covered with a high-resistance, inorganic coating to reduce eddy currents. The laminations are handled with minimum bending to preserve the low loss properties. The core is clamped in a rigid frame with uniform pressure to reduce mechanical effect on performance.

CORE & COIL ASSEMBLY:

MTPL 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. We use off circuit tap switches for general transformers, externally operated ON LOAD TAP CHANGER of OLG/CTR make for special transformers and furnace applications, whereas EASUN-MR make, INTANK type OLTC are used in Sub Merged Arc Melting Furnace Transformers, as per customer's technical specification.

TANK:

All our tanks are fabricated with high grade tested mild steel. The design of the tanks incorporate adequate wall and base thickness so as to withstand the pressure build up in the tank. Welding is carried out in accordance with strict standards using jigs and fixtures to ensure dimension accuracy. Double weld are provided where oil tightness is required. All oil tight weld are tested to ensure no leakages occurs. Flat gasket of neoprene bonded cork sheets are used for joints and auxiliary fitments. For ONAN Cooling, Pressed sheet steel radiators are used for cooling ensuring that greater surface area is available for high dissipation. The radiators are independently pressure tested and then mounted on the tank_ For ONAF Cooling, Fans are mounted vertically near the radiators for their optimum use. For OFVVF Cooling, Heat Exchangers, oil pumps, oil flow meter, water flow meter, pressure meters, differential pressure gauge is used to suit the losses of transformers at 150% loading condition.

Sub merged Arc melting furnace transformers are manufactured in 3 phase system upto 11 MVA and Bank of 3 nos, single phase, transformers for higher than 11 MVA transformers.

Three phase units are available in three ways :-

• Tap windings are in series with main HT windings in one core frame and in one tank with OLTC.
• Tap windings are separated through auto transformer in addition to main transformer, but both the transformers are in one common tank.
• Tap windings are through an auto transformer in separate tank with OLTC and main transformer is in another tank.

Single phase units are available in three ways :-

• Three single phase units having each unit, consisting of Tap windings in series with main HT windings in one core frame and in one tank with OLTC.
• Three single phase units having each unit consisting of separate Tap winding through Auto Transformer in addition to main transformer and in one tank with OLTC.
• Three single phase units having each unit consisting of only main transformer. The OLTC & three phase auto transformer shall be in separate tank.

Our 18 MVA (Bank of 3 nos. 6 MVA single phase transformers) are running successfully at Jai Balaji Group, Durgapur, 15 MVA (Bank of 3 nos 5 MVA single phase transformers) at Soya Group whereas 3 phase, 9 MVA transformers with separate auto transformers are running successfully at lmpex Ferrotech Ltd. & Vikash Steel & Power Limited, West Bengal.