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This article has been tagged since December 2006. Voltage drop is the reduction in voltage in an electrical circuit between the source and utilitization device. Voltage drop, which is present in all electrical circuits powering any device, must be considered to varying degrees in circuit design. In electrical wiring national and local electrical codes may set guidelines for maximum voltage drop allowed in a circuit, to ensure reasonable efficiency of distribution and proper operation of electrical equipment. International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ...
The article on electrical energy is located elsewhere. ...
An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, and switches. ...
Electrical wiring in general refers to insulated conductors used to carry electricity, and associated devices. ...
Fundamentals of voltage drop
A current flowing through the non-zero resistance of a practical conductor necessarily produces a voltage across that conductor. In alternating current circuits, additional opposition to current flow occurs due to the interaction between electric and magnetic fields and the current within the conductor; this opposition is called "impedance". Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...
In science and engineering, conductors are materials that contain movable charges of electricity. ...
City lights viewed in a motion blurred exposure. ...
The dc resistance of the conductor depends upon the conductor's length, cross-sectional area, type of material, and temperature. The impedance in an alternating current circuit depends on the spacing and dimensions of the conductors, the frequency of the current, and the magnetic permeability of the conductor and its surroundings.
Voltage drop may be neglected when the impedance of the interconnecting conductors is small relative to the other components of the circuit.
For example, an electric space heater may very well have a resistance of ten ohms, and the wires which supply it may have a resistance of 0.2 ohms, about 2% of the total circuit resistance. This means that 2% of the supplied voltage is actually being lost by the wire itself, and the intended load (the space heater) may be receiving an undervoltage. While electrical equipment is designed to operate over a range of voltages, excessive undervoltage may result in loss of performance, overload damage to electric motors and loss of operating efficiency. Rotating magnetic field as a sum of magnetic vectors from 3 phase coils An electric motor converts electrical energy into kinetic energy. ...
Voltage drop in direct current circuits A voltage drop is produced when a current flows through a conductor. The voltage measured from the supply end of a conductor (or one of many conductors in a circuit) to the load is called voltage drop. In electricity, current refers to electric current, which is the flow of electric charge. ...
In science and engineering, conductors are materials that contain movable charges of electricity. ...
 Fig. 1: The local voltages along the long line decrease gradually from the source to the load The local voltages along the long line having a resistance Rl may be measured, in order to build the voltage distribution (the voltage diagram). In this geometrical presentation (Fig.1), each local voltage drop is represented by a local bar with corresponding height (for simplicity, only the envelope of the voltage diagram is drawn). The idea of voltage diagram can be intuitively derived from many examples of human routine: hydraulic [1], pneumatic, mechanical, thermal, etc. These analogies help to understand that the local voltages along the line decrease gradually (linearly) from the source to the load. Actually, this arrangement reproduces the famous Ohm's experiment [2]. Image File history File links Download high-resolution version (1000x355, 43 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
Image File history File links Download high-resolution version (1000x355, 43 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
An analogy is a comparison between two different things, in order to highlight some form of similarity. ...
If the load resistance RL varies, the current I varies as well. As a result, all the local voltages along the line vary proportionally. The right end of the voltage diagram moves vertically while the left end is fixed at VIN level; the output voltage decreases - VOUT = VIN - VRl.
Voltage (and voltage drop) is typically measured in volts, current in amperes and impedence in ohms. The relationship among these values in direct current circuits is expressed in the equation V = IR (Ohm's Law). The resistance of the conductors will vary with operating temperature. Josephson junction array chip developed by NIST as a standard volt. ...
Current can be measured by a galvanometer, via the deflection of a magnetic needle in the magnetic field created by the current. ...
Ohm may refer to: The scientist Georg Ohm. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
Ohms law states that, in an electrical circuit, the current passing through a conductor is directly proportional to the potential difference applied across them provided all physical conditions are kept constant. ...
Voltage drop in alternating current circuits Alternating current is a current that continually reverses direction in a circuit in sinusoidal fashion. The current used in the distribution systems in North America alternates at 60 cycles per second (60 Hertz), while those in other parts of the world may alternate at 50 cycles per second. The voltage drop in an alternating current (AC) circuit is the product of the current and the impedance (Z) of the circuit. Impedance is analogous to resistance; impedance takes into account, however, the additional electromagnetic properties involved with alternating current loads. Electrical impedance, like resistance, is expressed in ohms and opposes current flow in a circuit. Electrical impedance is the vector sum of electrical resistance, capacitive reactance, and inductive reactance. The voltage drop occurring in an alternating current circuit is the product of the current and impedance of the circuit. It is expressed by the formula E = IZ, analogous to Ohm's law for direct current circuits. City lights viewed in a motion blurred exposure. ...
City lights viewed in a motion blurred exposure. ...
Electrical impedance, or simply impedance, is a measure of opposition to a sinusoidal alternating electric current. ...
Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...
In the analysis of an alternating-current electrical circuit (for example a RLC series circuit), reactance is the imaginary part of impedance, and is caused by the presence of inductors or capacitors in the circuit. ...
This article is about electronics. ...
Minimizing voltage drop...
...in power transmission Great distances often occur in electric power transmission. Any power generated, but not delivered to the customer, is a financial loss. Power is lost in the conductors throughout the entire length of the transmission lines. One (very expensive) way of reducing the lost power is to increase the conductor size and thus reduce the net resistance. Another way to minimize power lost because of voltage drop is to increase the voltage. This reduces the current for a given power transmission and hence the attendant voltage drop and power loss. However, the high voltages cause many problems; eg: corona losses, insulation breakdown of supports, magnetic influence to nearby objects, physical hazards. When we compare the two formulae for power(W = IE and W = I2R) it becomes evident that for a given amount of power transmitted, both the voltage drop and power loss are reduced when the current is decreased while the resistance remains constant. It is for this reason that utility supplied electrical mains are often at a very dangerous tens of thousands of volts; should the electricity have been transmitted to customers at the nominal end user voltage, the size, cost, and weight of the necessary conductors would be enormous. Power line redirects here. ...
...in data transmission
 Fig. 2: Compensation the line resistance by using a series connected negative resistor (it is supposed that the ground wire has zero resistance) Applyng a negative resistance. The line resistance Rl (the voltage drop across the line) can be compensated by connecting a negative resistor with a negative resistance -Rl in series with the input voltage source [3]. In this arrangement, the two elements constitute a voltage source with negative internal resistance. Image File history File links Download high-resolution version (1000x352, 49 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
Image File history File links Download high-resolution version (1000x352, 49 KB) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...
In electrical circuits, static resistance is the ratio of the voltage across a circuit element to the current through it. ...
The negative resistor consists of a "positive" resistor R = Rl and a "helping" voltage source BH. The "copy" resistor R converts the flowing current I into proportional "mirror" voltage drop VR = Rl.I, which drives the compensating voltage source BH (an amplifier with K = 2). As a result, the doubling voltage source BH produces an additional "helping" voltage VH= -2.Rl.I. A portion of this voltage compensates the voltage drop across the "copy" resistor R; the rest part compensates the voltage drop across the line resistance Rl.
When the current increases, the voltage source raises its output voltage so that the load voltage VL stays equal to the input voltage - VOUT = VIN. This idea may be implemented by an op-amp circuit of a negative impedance converter [4] (NIC). In this arrangement, the op-amp compares its output voltage with the "mirror" voltage drop across the "copy" resistance instead with the "original" line resistance (it "supposes" that the two resistances are equal). If the "original" resistance varies, the op-amp will be misled and an error will appear. Only, a negative resistance solution has an advantage - it has only two terminals; therefore, it needs only two wires. The negative impedance converter (NIC) is a configuration of an operational amplifier with the aim of creating a negative load. ...
Applyng a negative feedback. In contrast to this circuit solution, the op-amp of a transimpedance amplifier in a classical negative feedback solution compares its output voltage directly with the "original" voltage drop across the "harmful" resistance [5]. In this way, it compensates exactly the resistance even when it varies (for example, because of temperature or length variations). However, for this purpose the op-amp needs an additional voltage sense wire, in order to "observe" the virtual ground by its inverting input. Unfortunately, in many cases, this point is inaccessible. A transimpedance amplifier is a circuit that performs current to voltage transfomation and is sometimes known simply as a current-to-voltage converter. ...
Voltage drop in household wiring In household wiring good design requires that wire size be sufficient to keep power dissipation within limits so that the wiring will not be overheated. In a given wire, the power dissipation is a function of the current. The maximum safe current for a given conductor is known as ampacity. Ampacity is independent of the length of the conductor and the supplied voltage; it has only to do with conductor composition (for example, copper or aluminum), the area of the conductor, and ambient conditions (such as insulating materials on the wire, hottest ambient temperature along the wire, the temperature and voltage rating of the insulation in the given environment, the geometery of the installation, and so on). The circuits are protected by overcurrent devices to prevent exceeding the rated ampacity. However, this is only the first consideration when selecting conductor sizes for applications. Ampacity is the rms current which a device can carry within specified temperature limitations in a specified environment dependent upon: a) temperature rating, b) power loss, c) heat dissipation. ...
The second consideration, often neglected by well-meaning homeowners installing their own electrical circuits, is the voltage drop for a given circuit and load. As already discussed in this article, voltage drop through a conductor depends in part upon the total net resistivity of the conductor, which in turn depends upon the total length of the conductor. Circuit loads (toasters, televisions, and so forth) have supplied to them a voltage equal to the originally induced voltage at the circuit panel (nominally 120V in North America or 220V in Europe) minus the voltage drop across the supplying conductor.
The National Electric Code recommends (not requires) that no more than 5% voltage drop in feeder + branch circuit wiring provides reasonable efficiency of operation.
Exact wording from Art 210-19(A)(1), FPN No. 4: "Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, provide reasonable efficiency of operation. See FPN No.2 of 215.2(A)(3) for voltage drop on feeder conductors."
While for a lightbulb a large voltage drop will result in a harmless condition of slightly less bright light being produced, incorrect voltages induced onto delicate circuitry (as for example in a DVD player, computer, and so forth) may quite easily result in an electrically damaging condition. It is quite easy to have a circuit well within the ampacity guidelines for its wiring, but whose voltage drop is too large.
For these reasons, it is wise to size wiring not only for the total current to be drawn, but also to insure that the net voltage drop on the branch | single circuit conductor shall not exceed 3%, or 5% total for a feeder and the branch. This is particularly the case when running long lengths of wire from one end of a house or to an outbuilding. An outbuilding/shed at twenty meters from your circuit panel to which you intend to draw ten amps should not, for example, be serviced by 14 AWG wire (whose ampacity is nonetheless well over your ten amp intention) due to the voltage drop. In such cases, it is wise, to use larger, more expensive wire.
To measure the voltage drop in a household circuit, remove all loads from the circuit, and measure the supplied voltage with a (preferably digital) volt meter. Then, plug in a household appliance which draws 10-15 amps of purely resistive load (such as a toaster, hair dryer, or space heater) and measure the voltage now present at the outlet while such a device runs. A voltage drop shall be clearly visible; if the drop exceeds 3%, your voltage drop is higher than the commonly accepted limit. For example, if an unloaded outlet shows 118V dropping to just under 117V when a space heater is applied, your voltage drop is within acceptable limits. If the same circuit shows 110V when loaded, your voltage drop is excessive.
The National Electric Code In the United States the National Electric Code (NEC) specifies the wiring types and limitations for a variety of conditions. The National Electrical Code is Part 70 of a set of codes and standards set forth by the National Fire Protection Association (NFPA). ...
All references to Voltage Drop within the US National Electric Code (NFPA 70) are limited to Fine Print Notes (FPN), and are NOT mandatory, but rather are Explanator Material as defined in Art 90.5(C).
See also Electricity distribution is the penultimate process in the delivery of electric power, the part between transmission and user purchase from an electricity retailer. ...
Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...
Ohms law states that, in an electrical circuit, the current passing through a conductor is directly proportional to the potential difference applied across them provided all physical conditions are kept constant. ...
Kirchhoffs circuit laws are a pair of laws that deal with the conservation of charge and energy in electrical circuits, and were first described in 1845 by Gustav Kirchhoff. ...
Electrical conduction is the movement of electrically charged particles through matter. ...
In an electrical system, ground loop refers to an unwanted current that flows in a conductor connecting two points that are nominally at the same potential, ground, but are actually at different potentials. ...
A power cable is an assembly of two or more electrical conductors, usually held together with an overall sheath. ...
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