Voltage drop is the decrease in electric potential along the path of a current in a circuit.
It occurs in the internal resistance of the source, conductors, contacts, and connectors.
Voltage drop is undesirable as it dissipates some of the supplied energy.
Implications
Voltage drop affects power conversion in loads.
Example: A space heater with a resistance of 10 ohms and supply wires with a resistance of 0.2 ohms means roughly 2% voltage loss in wires.
Excessive voltage drop can lead to poor equipment performance and wire overheating.
Regulations
Electrical codes often specify maximum permissible voltage drop to ensure efficient distribution and proper operation.
Maximum allowed voltage drop varies internationally.
Compensation Techniques
Increasing conductor diameter reduces resistance and voltage drop.
Higher voltage usage in power distribution can reduce voltage drop.
Active elements may be used for further compensation.
Resistive DC Voltage Drop
Determined using Ohm's law: ( V = I \times R ).
Kirchhoff’s circuit laws state that the sum of voltage drops across all circuit components equals the supply voltage.
Physical properties like length, material, and temperature affect conductor resistance.
Larger resistors result in larger voltage drops, consuming more energy.
Reactive AC Voltage Drop
AC circuits face additional opposition due to reactance.
Impedance (( Z )) is the combination of resistance and reactance.
Impedance is calculated as a vector sum of resistance, capacitive reactance, and inductive reactance.
Voltage drop in AC circuits is given by ( E = I \times Z ).
Special Cases
Pn junctions in diodes and transistors have characteristic voltage drops when forward-biased, dissipating energy as photons in LEDs.
Related Concepts
Brownout, Capacitive dropper, Power distribution, Electrical resistivity and conductivity, Ground loop, Kirchhoff's voltage law, Mesh analysis, Power cable, Voltage divider, Voltage droop.