Technological advances in distribution transformers

Electrical energy has been used as a driving force in industrial units and power stations due to its versatility, usability and eco-friendliness. The electrical energy is easily transferred from one voltage level circuit to another voltage level circuit by transformers which are static electrical equipment. Transformers are robust and sturdy without any moving parts. These also require least maintenance compared to other electrical equipment.
Amorphous core transformersThe iron losses in transformers are about 0.15 per cent of total power transferred and 11.3 per cent of transformer losses. The iron losses account for 1.77 – 3.85 per cent of total input energy in an industry. These losses are mainly due to eddy current and hysteresis losses. The increased iron losses are due to idle charging, over sizing, use of inferior core material, and harmonics in the distribution system, to name a few.
The core losses have two components: eddy current losses and hysteresis losses. The hysteresis losses are directly proportional to frequency and more for non-linear loads.
In order to reduce these both iron losses, new amorphous cores are developed for transformers.
The amorphous core is made from a non-crystal substance created by rapidly freezing liquids of high temperature. Random molecular structure of amorphous metal core, there is no rule of atomic arrangement causes less (Fig. 1 and 2) friction than conventional silicon steel core when a magnetic field is applied. This property of amorphous core allows ease of magnetisation and demagnetisation reduces the hysteresis losses significantly.
As the eddy current losses are proportional to square of thickness of laminations, the thickness of laminations of amorphous cores will be of the about 0.025 mm which is about 1/10th of laminations of silicon steel. This causes reduction of eddy current losses considerably.
The overall reduction in iron losses (combination of both hysteresis and eddy current losses) in amorphous core transformer will reduced by 1/5th that of iron losses in silicon steel cores. At a flux density of 1.3 tesla, iron loss of amorphous core is about 0.27 W/kg where in silicon steel it is about 0.71 W/kg.
The amorphous core has higher electrical resistance, i.e. 130 μΩ-cm which is almost triple of silicon steel cores (50 μΩ‑cm). This higher resistance of amorphous core helps in reduction of eddy losses in core, i.e. when magnetic flux flows, eddy current flows to negate the flux.
Advantages of amorphous core transformers

Easy magnetisation due to low coercivity, low hysteresis loss and high permeability
Fast flux reversal due to low magnetic loss
Easy to construct and less maintenance
Single coil construction reduces the axial component whereas interlayer bonding by use of epoxy paper reduces radial component of short-circuit forces
Reduced iron losses reduce the heat generation considerably
Considerable reduction in losses in harmonic prone areas
Fast, easy repair due to its modular construction
Use of single quality (grade) core material
Easy lacing and unlacing of core for coil installation

Advertising