The fundamental difference between a transmission line and a feeder is that:
transmission line is longer and operates at more voltage than feeder
Understanding Transmission Line vs. Feeder
The question asks about the fundamental difference between a transmission line and a feeder in an electrical power system. These are two distinct parts of the power network, serving different purposes and operating under different conditions.
What is a Transmission Line?
- A transmission line is part of the transmission system.
- Its main purpose is to transfer bulk electrical power from generating stations to substations located near load centers.
- Transmission lines cover very long distances, often spanning hundreds or thousands of kilometers.
- They operate at very high voltages (typically hundreds of kilovolts, like 132 kV, 220 kV, 400 kV, 765 kV, etc.) to minimize power losses during long-distance transmission.
What is a Feeder?
- A feeder is part of the distribution system.
- Its main purpose is to distribute electrical power from a substation to various distribution transformers or directly to consumers in a specific area.
- Feeders cover shorter distances compared to transmission lines, usually within a city or a limited geographical region.
- They operate at relatively lower voltages compared to transmission lines (typically ranging from a few kilovolts up to tens of kilovolts, like 11 kV, 33 kV, etc.).
Key Differences: Transmission Line vs. Feeder
Based on their purpose, location in the network, length, and operating voltage, the key differences are:
| Feature | Transmission Line | Feeder |
|---|---|---|
| Purpose | Bulk power transfer | Power distribution |
| Length | Longer distance | Shorter distance |
| Operating Voltage | Higher voltage | Lower voltage |
| Location in System | Between generating station and substation | Between substation and distribution point/consumer |
Comparing this understanding with the given options:
- Option 1 suggests transmission line is shorter and operates at less voltage. This is incorrect.
- Option 2 suggests transmission line is longer and operates at more voltage. This aligns with the fundamental characteristics.
- Option 3 suggests transmission line is shorter and operates at more voltage. This is incorrect because transmission lines are longer.
- Option 4 suggests transmission line is longer and operates at less voltage. This is incorrect because transmission lines operate at more voltage.
Therefore, the fundamental difference lies in the transmission line being longer and operating at a significantly higher voltage compared to a feeder.
Important Questions from Distribution Systems
Which distribution system is more reliable?
Which of the following statements is INCORRECT?
In a DC 2-wire feeder, the drop per feeder conductor is 2%. Find the transmission efficiency of the feeder.
What is the percentage saving in feeder copper if the line voltage in a 2-wire DC systems is raised from 100 V to 200 V for the same power transmitted over the same power distance and having the same power loss?
A 2-wire DC distributor cable 800 m long is loaded with 1 A/m. Resistance of each conductor is 0.05 Ω/km. Calculate the maximum voltage drop if the distributor is fed from both ends with equal voltages of 220 V.
