The core substantial characteristics of significance to electrical machines are those related to conductors for electrical device, the insulation system essential to isolate the circuits, and with the specialized steels and permanent magnets used for the magnetic circuit.
Normally materials used for conducting are copper and aluminium. A number of the fascinating properties an honest conductor ought to possess are itemized below.
- Small Low value of temperature constant of resistance.
- Small value of resistance or high conductivity.
- High resistance to corrosion.
- High stringiness.
- High freezing point.
- Allow brazing, bonding or welding in order that the joints are reliable.
- Extremely malleable and ductile. Robust and economical by cost.
Certain properties of the copper and aluminium are tabulated below:
|1||Resistivity at 200C||0.0172 ohm/m/mm2||0.0269 ohm/m/mm2|
|2||Conductivity at 200C||58.14 x 106 S/m||37.2 x 106 S/m|
|3||Density at 200C||8933kg/m3||2689.9m3|
|4||Temperature coefficient (0-100oC)||Explanation: If the temperature increases by 1oC, the resistance increases by 0.4% in case of aluminium|
|5||Coefficient of linear expansion (0-100oC)||16.8x10-6 per oC||23.5 x10-6 per oC|
|6||Tensile strength||25 to 40 kg/mm2||10 to 18 kg/mm2|
|7||Mechanical property||highly malleable and ductile||not highly malleable and ductile|
|9||Thermal conductivity (0-599 W/m 0C||599 W/m 0C||238 W/m 0C|
can be easily soldered
|cannot be soldered easily|
For an equivalent resistance and length, cross-sectional space of Aluminium is almost 60% larger than that of the copper conductor and virtually 50% lighter than copper.
Though the Aluminium reduces the price of little capability transformers, it will increase the dimensions and price of huge capacity transformers. Aluminium is being a lot of used currently a day’s solely as a result of copper is lavish and not simply offered. Aluminium is nearly 50% cheaper than Copper and not a lot of superior to copper.