A DC motor draws 100 amperes at full load from a 220-volt DC...

Name: Problem 4, Chapter 9: Electricity 1: Devices, Circuits and Materials
Uploaded: 2019-03-29T08:08:44-08:00
Duration: 2 min 51 s
Channel: Ceren Uzun
Description: A DC motor draws 100 amperes at full load from a 220-volt DC source 200 feet away. If a 3 percent line voltage loss is permissible, find the wire size to be used for the line conductors. K = 12.9.

A DC motor draws 100 amperes at full load from a 220-volt DC source 200 feet away. If a 3 percent line voltage loss is permissible, find the wire size to be used for the line conductors. K = 12.9. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________

A DC motor draws 100 amperes at full load from a 220-volt DC source 200 feet away. If a 3 percent line voltage loss is permissible, find the wire size to be used for the line conductors. K = 12.9.
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Key Concepts

Voltage Drop Calculation

This concept involves determining the reduction in voltage that occurs along a conductor due to its inherent resistance when current flows through it. It is calculated by taking into account the current, the conductor's resistive properties, and the distance over which the current travels. In electrical power systems, ensuring that the voltage drop does not exceed a specified limit is critical for proper equipment operation.

Permissible Percentage Voltage Drop

This is the maximum percentage of the source voltage that can be lost due to resistance in the conductors while still ensuring that the load receives adequate voltage. In many applications, such as motor circuits, manufacturers or standards specify a limited voltage drop (for example, 3% of the source voltage) to maintain system efficiency and proper functioning.

Conductor Sizing Using Circular Mils

Conductor sizing is often based on the cross?sectional area expressed in circular mils (cmil), a unit that accounts for the area of a round wire. Determining the proper conductor size involves using voltage drop formulas that incorporate current, distance, resistivity constants, and the maximum allowable voltage drop. This ensures the conductor has sufficient capacity to carry the current with minimal losses.

Resistivity Constant (K Value)

The constant K represents a factor that relates to the material’s resistivity and the units used for length and conductor area in the voltage drop formula. It encapsulates how the conductor material (such as copper or aluminum) impacts the voltage drop for a given current and length. Understanding and applying the correct K value is crucial for accurate conductor sizing in DC circuits.

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