What is Voltage drop: Definition and 200 Discussions

Voltage drop is the decrease of electrical potential along the path of a current flowing in an electrical circuit. Voltage drops in the internal resistance of the source, across conductors, across contacts, and across connectors are undesirable because some of the energy supplied is dissipated. The voltage drop across the electrical load is proportional to the power available to be converted in that load to some other useful form of energy.
For example, an electric space heater may have a resistance of ten ohms, and the wires that supply it may have a resistance of 0.2 ohms, about 2% of the total circuit resistance. This means that approximately 2% of the supplied voltage is lost in the wire itself. An excessive voltage drop may result in the unsatisfactory performance of a space heater and overheating of the wires and connections.
National and local electrical codes may set guidelines for the maximum voltage drop allowed in electrical wiring to ensure efficiency of distribution and proper operation of electrical equipment. The maximum permitted voltage drop varies from one country to another. In electronic design and power transmission, various techniques are employed to compensate for the effect of voltage drop on long circuits or where voltage levels must be accurately maintained. The simplest way to reduce voltage drop is to increase the diameter of the conductor between the source and the load, which lowers the overall resistance. In power distribution systems, a given amount of power can be transmitted with less voltage drop if a higher voltage is used. More sophisticated techniques use active elements to compensate for excessive voltage drop.

View More On Wikipedia.org
Recent contents Top users
  1. J

    Voltage drop for a charged capacitor

    Homework Statement What is the voltage drop across the 1000 Ohm resistor when capacitor is fully charged? Homework Equations V(t) = {V_i}*e^{-t/RC} = {V_i}*e^{-t/Tau} The Attempt at a Solution In RC circuit experiment, initial is 9V and final is 2V. The voltage drop should be difference...
  2. Mr Davis 97

    Why does an element in a circuit cause a "voltage drop"

    I have seen this topic in other threads before, but I have not found an answer that eliminates my confusion. I know that electric potential is defined so that only the position of a charge with respect to a field determines the quantity of the electric potential (voltage). This allows us to...
  3. G

    Can local voltage drop be developed over ground plane?

    Hello. The ground plane is sometimes used as current return path. If current is low frequency and amplitude is small then voltage rising due to current flow can be ignorable. However, what is return current is actually very high in both frequency and amplitude? In our lab, gas discharge...
  4. Rob1818

    BJT Collector to Emitter voltage

    I have been checking the BJTs on a car audio amplifier board with my DMM's diode test feature, and I need a little help understanding something I have been noticing: The base to emitter and base to collector voltage drops are present, and show an open circuit when the leads are reversed as they...
  5. J

    Why do resistors always cause a voltage drop equal to the voltage applied?

    Consider a wire connected to a battery. Now,potential is analogous to the energy of the particles.And potential in a resistor drops because of the friction inside the resistor(considering there is no friction along the wire and outside the resistor).So the friction determines how much energy is...
  6. I

    Engineering Analyzing diode circuit with Constant Voltage Drop model

    Homework Statement Homework Equations Whenever assuming a diode is "on", replace that diode with a 0.7 voltage source. Whenever assuming a diode is "off", replace that diode with an open circuit. The Attempt at a Solution The problem is pretty straightforward but the format of the circuit...
  7. dwn

    Power Supply voltage drop issue

    I've built a small voltage regulator that I can use with my breadboard or to test circuits. It is the first circuit that I've actually soldered together, so please disregard the hack job. The problem with the circuit is that when I hook up a very small load to the supply, the voltage plummets. A...
  8. C

    What causes changes in electric field within a circuit?

    So I'm having trouble visualizing how voltage drops more within different parts of a circuit, such as a resistor vs. wire. I know all the general equations but the concept is hard for me to comprehend and I am stuck on one notion. So, say you have a simple DC circuit with just a resistor and...
  9. P

    Overall Power Factor of three motors for transformer voltage drop calculation

    Hi Suppose I have three motors connected to a single busbar which is fed by a single transformer and suppose that the current into the busbar (i.e. the total current of the transformer secondary) is known. If I wish to calculate the transformer voltage drop the I will obviously need the load...
  10. O

    Voltage drop across resistors

    Homework Statement Determine the voltage at each labelled point with respect to ground Homework Equations V*r1/(r1+r2) i*r1/(r1+r2) i=v/R The Attempt at a SolutionI'm doing a practice problem and I can't seem to get the right answer. I just want direction in the way to solve it, these are...
  11. S

    General DC Circuit: Voltage drop different from supply source

    Homework Statement I performed a lab with a simple DC circuit. The circuit has 4 resistors (i.e. R1, R2, R3 and R4), which is the same as shown in the attached image. When the voltages across all resistors were added, they were higher than the source. How is this possible? The KVL rule states...
  12. P

    Dyn Transformer voltage drop

    Homework Statement A 3MVA 11kV/415V 3 Phase Transformer has the following parameters +ve sequence resistance = 0.00355pu +ve sequence reactance = 0.0901pu Primary PHASE current to the transformer is 55A and the load power factor on secondary is 0.85 lagging. Calculate voltage Drop The...
  13. M

    Need to calculate the resistance accross membrane in water

    Hello everybody, I am chemist. and I prepare ionic membrane and placed in a home made acrylic cell containing 0.1M NaCl separated into two portions by ionic membrane. I applied DC voltage of 9.6V (using 9V battery). Using multi-meter the measured DC voltage in water was 4.45V. The distance...
  14. J

    Understand Voltage Drop in Series Circuits: Questions Answered

    Hi all, I have a question about voltage drop of a battery. I understand Kirchoff's laws well, but it occurred to me that I did not understand intuitively why the "zero volts" at the end leg of a series circuit would still produce current. Theoretically you could have the majority of a series...
  15. U

    Power dissipated by a resistor in combined citcuit

    Find the power dissipated by R2 given that V a-b=120 volts, R1=1, R2=3.33, R3=2, and R4=3 I've worked this problem, just want to confirm I worked it correctly. A---------R1-----------*------------------- | |...
  16. A

    Actual resistance of an Ammeter

    Hi, I want to use a digital ammeter to measure the current flow though a Raspberry pi. The Pi uses about 700mA and is 5V so its got a resiatance of about 7 ohms. Therefore something like 0.5 ohm ammeter will have a large voltage drop of about 0.3V which is way too large and would lead to the...
  17. genxium

    Voltage drop across ideal solenoidal inductor

    First by ideal I mean zero resistance. I tried to verify Faraday's law in simple LCR circuit but ran into some conflicting results. Though the description below will be a little verbose, the configuration for this problem is extremely simple: assume that I put a solenoid...
  18. L

    Notation for marking the voltage drop in this picture

    Homework Statement When we write the V_0 on the right of the diagram as show below, between which two points does the voltage drop refer to? There are two nodes on the top correct? I am assuming the voltage drop refers to the two rightmost nodes. I've tried to circle the nodes. See this...
  19. N

    Voltage drop over an independent current source?

    Homework Statement I am supposed to give a thevenin equivalent circuit to the one posted in the picture. Homework Equations V=IR KVL: "voltage drops around a closed loop sums to zero KCL: "current into a node equals current out of a node" The Attempt at a Solution The part I'm confused...
  20. M

    Governing Equation for an electrical system

    Homework Statement Homework Equations Kirchoff's Voltage/Current Law The Attempt at a Solution I first started by summing up the currents at node 1, which is the intersection of 3 wires at the top, and node 2, which is between the capacitor and inductor. So, at node 1: $$ \sum i = -i(t) +...
  21. H

    Voltage drop question - need check/advice

    1. Homework Statement What do you predict the voltage will be measured from B to D directly? Vtot = 1.0 V peak-peak Two parallel branches, one with two 1.5 kOhm resistors in series, one with a 1.5 kOhm resistor and a 0.1 μF capacitor in series (see attached diagram) Homework Equations V=IR...
  22. Rugile

    AC circuit - voltage drop and resonance

    Homework Statement An AC voltmeter connected to the nodes A and B shows the same value as when connected to the nodes A and D (refer to attachment). What is the inductance of the inductor? What value does the voltmeter show? The inductor is ideal. U = 70sin(314t) V, C = 80 μF, R = 500 Ω...
  23. S

    Engineering Help with circuits (Current, Voltage Drop, and Power Dissipation)

    Homework Statement Basically, I need to know the power dissipation (W) for three resistors using aw 12V battery: 120, 80, and 50 ohms. https://webwork2.uncc.edu/webwork2_files/tmp/Fall2014-Engr1201-Common/img/2ff2f0ce-cb10-3786-8109-c42346130316___1a2e5eeb-8657-3983-941f-b7d8a9123afa.gif...
  24. BeautifulLight

    I don't understand how I am "calculating for the voltage drop"

    Assume I have connected a single light-emitting diode (2V, 30mA) and resistor to a standard 9V battery. Ohm's Law is used to calculate the value for the resistor. The observed relationship between voltage, current, and resistance is as follows, V=IR. I intuitively understand there will be a...
  25. S

    How to measure voltage drop

    Hi I am very confused how can measure voltage drop of a sheet if 1 Ampere is passed and the sheet has a resistance of 0,01 ohm in sq does it matter the thickness of the sheet ?
  26. J

    Dramatic voltage drop at voltage regulator output

    First time posting a problem on here. Be gentle on me :) So I ran into this problem when I was testing the power supply block for my senior project.I attached a pic...
  27. K

    Electric potential difference vs. voltage drop

    Are these the same thing? Or does the electrical potential difference refer to the voltage source only?
  28. R

    Engineering Voltage drop w/ series/parallel circuit

    Homework Statement Find the voltage drop (V0) across the 3 kΩ resistor Circuit Pic: http://i.imgur.com/kX7hlQK.png CS1= 14mA CS2= 27mA R1 = 7kΩ R2 = 7kΩ R3 = 3kΩ Homework Equations Ohms Law & Current Division The Attempt at a Solution 1) First thing I did was combine the two...
  29. N

    Forward voltage drop across an LED

    Hi guys, I'm trying to design circuits that include mostly ohmic devices with the exception of some LEDs. In particular, I'm having trouble coming up with an effective voltage drop across an LED. This is the datasheet for the particular LED that I'm trying to include in the circuit. It has a...
  30. P

    Voltage drop through a transformer

    Hi, I understand that for a real transformer there will obviously be a current drop through the transformer due to winding resistance, core losses hysteresis etc. For the sake of power system analysis, however, do you still assume that the secondary and primary voltages are linked by terms of...
  31. T

    Voltage Drop & EMF: Inductor Circuit Explained

    Hello, Please i have a question.When we have an inductor in a circuit we say that we have 2 electric field : conservative and non-conservative. so who is doing work on the charges?if we draw an rl circuit with a DC source the conservative electric field across the inductor has the same...
  32. D

    How to compensate for voltage drop across a diode?

    Hi, I am working on a project where I am using a LCD voltage display to measure voltage at 2 points in the circuit. The first is the voltage of the batteries providing the power, and the second is to measure the output of the circuit. It is in a very small box and I don't have room for a...
  33. G

    LC Filter Voltage Drop Considerations

    Hi, I've gotten a little confused and would like some guidance and confirmation, I've designed an H-Bridge inverter which should output 100A at 20Vrms onto a 200mΩ load. The current target output peak voltage (with max duty cycle of 98% considered) is 28.86V. The LC filter is made up of a...
  34. N

    Voltage Drop Calculation for Bus 2?

    Hi, This is not really homework but since it's homework style, I'll post it here and maybe benefit someone else. Homework Statement I need to calculate the final voltage on Bus 2 (labeled B2 in attached PDF). I am trying to do this using per units and my attempt is attached. The...
  35. T

    Determining Current and Voltage Drop in RLC Circuit

    Homework Statement A circuit contains a 100Ω resistor, a .0500H inductor, a .400μF capacitor, and a source of time-varying emf connected in series. The time-varying emf is 50.0 V at a frequency of 2000 Hz. a) Determine the current in the circuit. b) Determine the voltage drop across...
  36. C

    Simple voltage drop / sign convention

    Homework Statement Find Vad and VebHomework Equations voltage drop, KVLThe Attempt at a Solution I actually did: Vad -24V - 4V + 6V = -22V but this is wrong.I know going the other way Vad: 6V + 8V + 12V = 26V, because it is only drop, and plus to minus on drops means they are...
  37. Q

    Understanding Voltage Drop in Wires: Causes and Solutions

    Hi Why is there a voltage drop in a wire when there is a high current flowing ?. Is this due to the electrons colliding with the lattice which causes the kinetic energy that the electrons have gained trough the voltage to be transfer to heat energy ?
  38. C

    How Long Can Copper Wire Be in a Data Center to Limit Voltage Drop to 1V?

    Homework Statement Your data center has 100,000 CPUs. Each burns 100 W at 120 V. Copper has a resistivity of 1.7E-8 Ω*m. What is the maximum length of copper wire on the power supply to give a voltage drop of no more than 1V? Homework Equations P = V*I R = (rho*L)/A, where L is the...
  39. B

    Voltage drop across resistor

    I'm curious the amount the voltage would drop across a resisitor. If you know the power going into the resistor and the maximum voltage allowed is say, 50V. How would that resistor effect the voltage? I understand the voltage would decrease, and when substituting and solving equations the new...
  40. C

    Given impedance, find voltage drop across resistor

    Homework Statement Determine the voltage V0 in the following network if the impedance Z contains: a. a 0.5 mH inductor b.a 10 μF inductor Homework Equations Voltage division for 2 series resistors: (v in)(resistor/total series resistance) ZL = ωLj Zc = -1j/ωC Z = ZL + ZC + R Zmagnitude =...
  41. P

    Forward biased ideal diode=>no voltage drop?

    Forward biased "ideal" diode=>no voltage drop? Does a forward biased ideal diode have no voltage drop?
  42. M

    How Does Voltage Drop Across a Resistor?

    Hello, I am having conceptual difficulties trying to understand how voltage is dropped across a resistor. The whole idea of it is confusing to me, where does this voltage go? Could it be explained in terms of point charges and electric fields, which is how I am able to visualize potential...
  43. A

    Voltage drop across capacitor in RC circuit

    Homework Statement Please look at the attachment for the circuit. The question is this: The switch has been closed for a long time. It is then opened. How long does it take for the potential across the 4μF capacitor to fall to half of its initial value? Homework Equations V =...
  44. C

    Why is there a voltage drop across an impedance?

    Firstly, there are lots of ways to word the definition of voltage, but the one that intuitively makes the most sense to me is as follows: "One volt is when: The difference in (electrical potential energy per unit charge (q)) between two places equals one." *per unit charge meaning the...
  45. J

    Archived Therefore the voltage needs to drop by 42V for the light bulb to be 40 watts.

    Homework Statement The light bulb is 60 watts at 230 volts, how much does the voltage need to drop for the lightbulb to be 40 watts'?Homework Equations V=IA, P=IV, P=IR^2, V=IR The Attempt at a Solution I tried 60w/230v=0,26A... 40w=0,26A*XV<->x=154V so voltage drop is 230-154=76.. I know...
  46. Drakkith

    Voltage Drop in a Series Circuit with 100V & 2 50 Ohm Resistors

    Ok, let's say you have a 100v voltage supply and two 50 Ohm resistors in a series circuit. The total resistance is 100 Ohms, leading to a current of 1 amp. Now my question is, what exactly is voltage drop? I know the voltage drop across each resistor is 50 volts. If we were to look at one of...
  47. B

    Compound circuit voltage drop along parallel component

    Homework Statement http://imageshack.us/a/img197/3519/circuith.png Equivalent Resistance of circuit = 17.31 Ω Homework Equations V = I * R The Attempt at a Solution Total voltage of the circuit, if I'm doing this correctly should be: E = (3.00 A) * (17.31 Ω) = 51.93 V...
  48. E

    Engineering Voltage drop across a diode in a high-amperage circuit

    I'm given a strange single-diode circuit where you must find out whether or not the diode is on. See the top diagram in the linked image: http://i.imgur.com/y1sn3.png (Current source is indeed 1 Amp, not 1mA as the 2kΩ resistor would suggest. Please do not try to correct the initial question...
  49. I

    Can Voltage Drop be Eliminated in High Current Circuits with Long Distances?

    Hey guys, I am new here so I figured I would post a problem I am having and see what comes out. I am designing a circuit that will force a voltage across a proprietary load that I cannot divulge on, but for this example we will assume it's resistors. So far everything works great but I am still...
  50. S

    Turbine ECU starter voltage drop

    Hi Guys, I have a model gas turbine that is driven by an ecu ... the ecu starter output is 12.6volts but the starter motor is rated to 6volts. The ECU can easily supply 20amps although the starter motor is rated to 5amps max efficiency. I need to drop the voltage from 12.6volts to...
Back
Top