FACTORS AFFECTING LOSSES IN DISTRIBUTION LINES

FACTORS AFFECTING LOSSES IN DISTRIBUTION LINES

Power distribution lines nature is to cater loads from every part of a certain area. Also, a typical electrical distribution system is a mesh of distribution lines supplying different kinds of customers from residential to industrial type. Due to the complexity of these networks, a careful analysis is needed to properly evaluate the performance of a certain feeder.

Analyzing losses in distribution lines is a very challenging role since it entails careful consideration of all the factors present that affects the losses in a distribution system. Although we have discussed previously that loss in the distribution line follows the I squared R law formula and the key to all of these loss evaluation and reduction is through the line current, ways in reducing the current may not be as easy as it seems.

The following terms below are some of the known factors that directly or indirectly influence the losses present in distribution lines. An electric utility that wishes to reduce their line losses to a minimum level should consider first these factors.

1. Line Conductors Used – Conductors plays a major role in the utilities quest to minimize losses. The right kind of material and size of the wire used can greatly affect the level of losses it can generate during its operation. Like any other wires, conductors used for power distribution possesses an inherent characteristics called impedance. Through the component of impedance which is the wires resistance, power loss is generated in the wires in the form of heat. Size of wire is inversely proportional to its resistance, meaning the larger the wire size is, the lesser its resistance will be. Consequently, larger wire sizes will generate less loss and smaller wire sizes will have larger loss produced.

2. Feeder Circuit Kilometer – this factor is somewhat similar to the conductors used since they are all resistance based factors. This factor still has something to do with line resistance in the distribution lines. The longer distance that the distribution lines travels will also yield a higher loss in the system. Recalling our electrical basics, wire resistance is directly proportional to the length of the wire. Over-extended lines tend to create large voltage drops, so, when voltage level drops in order for the system to produce the necessary supply, more current will be drawn-out resulting in higher losses generated.

3. Load conditions – load cycle in any utility is dynamic. The loading that the feeders accommodate is said to vary with respect to the time of day. There is what we call a peak load moment and the light load moment. Since power loss is a function of current and current is directly proportional to the kilo-volt-ampere loading, a varying load also creates a varying distribution line loss, meaning the maximum distribution loss recorded will be during the maximum load that the feeder experienced.

4. Nature of Loads – different types of loads basically exist in a power system. An electrical load is a function of a kilowatt load and a reactive load. An inductive load tends to draw-out higher lagging current than that of a purely resistive load. So having loads that are highly inductive like motor loads will produce higher losses in the system since higher current will also be necessary in order for the load to operate.

5. Operating Voltage – The higher the voltage level used to operate distribution lines will most likely reduce losses in the system. Referring to the power formula P = 3 x V x I x power factor, when increasing the operating voltage, in order to have the same power, the value of current drops down. When current level drops down, it is therefore logical to conclude that reduction in line losses will occur.

6. Phase Balancing – this has usually been a problem whenever utilities have poor load monitoring system. An unbalanced load tends to produce more losses especially to the phase where the current is concentrated. Remember that line loss is an exponential factor of the line current i.e. a 50A – 50A – 50A 3-phase loading will have lesser line loss than a 100A-25A-25A loading using the I squared R formula.

7. Circuit Configurations – similar to that of item #2, loss reduction in interconnected feeders can be obtained by proper circuit configuration. The objective of which is to optimize maximum loading capabilities of adjacent feeders for them to have a combined loss that is lesser to that of the previous configuration.