Basics of Power Systems and Transmission Lines

Fill-in-the-blank practice flashcards covering power system grids, voltage classifications, distribution components, AC/DC comparison, Kelvin's Law, and cable types.

NLDC stands for National Level Load Dispatch Centre, while SLDC stands for State Level Load __________.

Dispatch Centre

As of May/June 2026, India's target is to achieve $500\,\text{GW}$ non-fossil capacity by 2030 and Net Zero by __________..

2070

In a primary transmission system, voltage is stepped up from $11\,\text{kV}$ to values such as $132\,\text{kV}$, $220\,\text{kV}$, or __________.

400 kV

The secondary distribution system uses a $11\,\text{kV}/415\,\text{V}$ substation transformer with its secondary winding connected in __________.

Star

The main consideration in the design of a feeder is its __________ carrying capacity.

current

While designing a distributor, __________ along its length is the main consideration.

voltage drop

According to voltage classification, Ultra High Voltage (UHV) refers to voltages of __________ and above.

765 kV

According to IE Rule 55, the limit of frequency variation must not be more than __________.

$$\pm 3\%$$

Underground cables categorized as Super Tension (S.T.) cables are designed for working voltages between $11\,\text{kV}$ and __________.

33 kV

An H-type cable is suitable for operating voltages up to __________.

33 kV

A strategic, hours-long voltage sag caused by system overload to prevent a blackout is known as a __________.

brownout

Unlike AC transmission systems, DC transmission lines do not suffer from __________ effect.

skin

Steel-cored aluminum conductors on steel lattice towers are roughly __________ times cheaper than the equivalent underground cable.

16

The volume of conductor material required in a 3-phase AC transmission line is inversely proportional to $V^2 \cos^2(\phi)$, where $\cos(\phi)$ is the __________.

power factor

Roughly, the most economical transmission voltage can be chosen as __________ per kilometer.

650 V

For overhead transmission lines, the breakeven distance where DC becomes more economical than AC is between $500\,\text{km}$ and __________.

800 km

Kelvin's Law states that the most economical conductor size occurs when the variable part of annual fixed charges equals the annual cost of __________.

energy wasted

Underground transmission systems are generally limited to working voltages up to __________.

66 kV