What is the distribution voltage in electricity transmission?

Answer 1

Every conductor (in this case, the transmission line) has a finite resistance. so for example let us say it has a resistance of 1 ohm over a distance of 1 km. then, if the current through the conductor is say 100 Amperes, you will have a voltage drop of 100 volts across a length of 1 km.

So, a line carrying 100 Amps at 25 kV will have an effective voltage of 24.9 kV

Answer 2

A metropolitan area is served by 69-kV and 138-kV networks, both feeding multiple distribution substations. A 230-kV network is also present, which feeds selected points within the 138-kV network. There are a couple of 500-kV nodes nearby that supply bulk-power from an interstate regional power pool. In this example, both the 69-kV and 13.8-kV systems are sub-transmission, while the infrastructure operating at 230 kV and 500 kV is considered to be transmission. A largely rural area is served with a 230-kV network, in which cities and towns have 230-kV high-voltage distribution substations. There is also a 69-kV network to feed some of the smaller substations in outlying areas. The 230-kV network is the transmission network while the 69-kV network represents a sub-transmission system. These substations may also include transformers connecting higher-voltage transmission with a lower-voltage sub-transmission network. The distribution system provides the delivery network to individual homes and businesses. Common distribution voltages include 12.5 kV, 13.2kV.

For most of the regulated history of electric utilities, the voltages used in the distribution delivery systems were allowed to vary within defined limits, mostly plus or minus 5%. As systems operated constantly at the upper 5% limit, these limits became the new nominal operating level. Therefore, 7.2/12.47-kV systems became 7.6/13.2-kV systems, which then evolved to 7.9/13.8-kV systems. In addition, the 7.2/12.47-kV system was doubled to provide the 14.4/25-kV system often used by the aforementioned REA delivery systems serving remote, sparsely populated areas. The desire for even higher distribution primary delivery voltages required an evolution of the transmission voltages used in the early years of electric system development. The 11-kV delta lines were upgraded, again by a factor of three, to 33 kV. As these were consistently operated at a 5% operating level, to reduce losses and offset voltage drop on the lines, a new nominal level of 34.5 kV was established.

Power transmission lines by their nature have to carry power long distances. Since there is a voltage drop involved, the voltage is increased at the source so that the loss in the transmission lines still allow usable power to be delivered at the user location. The higher voltage is reduced by a transformer near your home to the standard 120 to 240 VAC.

Answer 3

There are three levels of nominal voltage used in the electricity supply system -those associated with transmission systems, and those associated with high- and low-voltage distribution systems. The voltages depend on the standards of the countries in which the systems are constructed. For example, in the UK,

• transmission voltages: 400 kV, 275 kV
• h.v. distribution voltages: 132 kV, 66 kV, 33 kV, and 11 kV
• l.v. distribution voltages: 400/230 V

Answer 4

What do you mean by "Primary Line"? There are typical voltage ranges for transmission, subtransmission, and distribution lines.

Answer 5

It depends on the particular utility. In the area where I live, the distribution voltage is 13.2 KV, phase to phase, or 7.62 KV phase to ground.