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The most suitable practical value of primary distribution is?
66 kV
11 kV
230 V / 415 V
22 kV
11 kV
In an electrical power system, primary distribution refers to the stage where the voltage from the transmission substation is stepped down to a medium-voltage level for distribution to various local areas. The standard industrial and commercial practical value for primary distribution in India is 11 kV.
In an electrical power system, primary distribution refers to the stage where the voltage from the transmission substation is stepped down to a medium-voltage level for distribution to various local areas. The standard industrial and commercial practical value for primary distribution in India is 11 kV.
VprimaryтАЛ>VsecondaryтАЛ тАФ Voltage relationship between primary and secondary distribution stages
P=3тАЛVLтАЛILтАЛcos╧Х тАФ Relation for power transmitted in three-phase distribution
The primary distribution system receives power from transmission substations via step-down transformers. This voltage (typically 11 kV or 33 kV) is carried by primary feeders to distribution transformers located near the load centers. These distribution transformers further step down the voltage to secondary distribution levels (415V/230V) for end-user consumption.
Primary distribution voltage is chosen based on the load density and distance of the area.
11 kV is the most widely adopted standard in urban and suburban areas for primary distribution.
Higher voltages like 33 kV are often used for primary distribution in sparsely populated or heavy industrial zones.
Secondary distribution follows the primary distribution and provides 415 V (three-phase) or 230 V (single-phase) to consumers.
Reduced transmission losses compared to lower voltages.
Lower current levels allow for smaller conductor cross-sections, saving copper/aluminum costs.
Improved voltage regulation over the distribution line.
Requires more expensive insulation compared to secondary systems.
High-voltage equipment (transformers/switchgear) is costlier to install and maintain.
Urban residential power grids
Commercial complex power supply
Small-scale industrial zones
Primary distribution is the voltage level between the distribution substation and the distribution transformer.
Option A (66 kV) is typically classified as sub-transmission. Options C (230 V/415 V) represent secondary distribution.
B is correct тАФ 11 kV is the standard and most practical voltage level used for primary distribution systems in India.
Always remember the standard sequence: Generation тЖТ Transmission тЖТ Sub-transmission (66/33kV) тЖТ Primary Distribution (11kV) тЖТ Secondary Distribution (415/230V).