DISTRIBUTION SYSTEM: RADIAL FEEDERS

DISTRIBUTION SYSTEM: RADIAL FEEDERS

Radial feeder is a distribution feeder line configuration that is known to have one path for power to flow, from the distribution substations (source) to utilization point (end-users). Electric utilities typically have one or more distribution substations each of which consist of one or more distribution feeders. A typical feeder is made up of some if not all of the following components.

• Primary main feeder (three phase)
• Lateral lines (three-phase, vee-phase and single phase)
• Voltage Regulators (usually step-type)
• In-line transformers
• Capacitor Banks (shunt)
• Distribution Transformers
• Secondary/Low-voltage lines
• Loads (three-phase, two-phase and single phase)

Radial feeders can also be described as a distribution line set-up where no other interconnected feeder line is adjacent to it. An outage in its distribution substation means an outage to the whole feeder. Radial feeder can usually be found in the outskirts of the franchise area where loads are in a relatively rural location.

Radial feeders seldom exists in the utilities urban areas since the reliability and flexibility of the supplies must be satisfied. Also, due to the load concentration that urban areas have, it would be very risky to use a radial feeder configuration.

DISTRIBUTION SYSTEM: DISTRIBUTION FEEDER ELECTRICAL CHARACTERISTICS

Referring to a book by William H. Kersting entitled “Distribution System Modeling and Analysis”, the electrical characteristics that distribution feeders should have before any analysis can be done must include the following data.

1. Overhead and underground spacings
2. Conductor Tables
         a. Geometric Mean Radius (GMR)
         b. Diameter
         c. Resistance
3. Voltage Regulators
         a. Potential Transformer Ratios
         b. Current Transformers Ratios
         c. Compensator settings
                   i. Voltage level
                   ii. Bandwidth
                   iii. R and X settings in volts
4. Transformers
         a. kVA ratings
         b. Voltage ratings
         c. Impedance (R and X)
         d. No-load power loss

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