What is Current loop: Definition and 103 Discussions

In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors. Only one current level can be present at any time.
A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to PID controllers, SCADA systems, and programmable logic controllers (PLCs). They are also used to transmit controller outputs to the modulating field devices such as control valves. These loops have the advantages of simplicity and noise immunity, and have a large international user and equipment supplier base. Some 4–20 mA field devices can be powered by the current loop itself, removing the need for separate power supplies, and the "smart" HART protocol uses the loop for communications between field devices and controllers. Various automation protocols may replace analog current loops, but 4–20 mA is still a principal industrial standard.

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  1. Boltzman Oscillation

    Help finding the magnetic field of a current loop

    Hi all, my work is shown on the attached image. The boxed equation is what I get to but I do not understand how to go from there to what the book has. I am guessing that the problem arises when trying to solve the cross product. I understand that I will need to find the value of the sine of the...
  2. P

    I Energetic argument for the tension in a current loop

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  3. M

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  4. greg_rack

    Torque on a current loop caused by a magnetic field

    Okay, so, the magnetic field lying(parallel) to the plane of the coil is confusing me quite a bit. Usually, in this kind of problem, we have a magnetic field directed perpendicularly to the plane. Considering this orientation of the field, wouldn't the torque on this sort of "elementary brush...
  5. S

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  6. P

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  7. Leo Liu

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  8. K

    What is causing the strange ground current loop in this motor circuit?

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  9. S

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  10. Luxucs

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  11. O

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  12. pobro44

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  13. Z

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  14. astrocytosis

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  15. M

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  16. G

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  17. FelixTheWhale

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  18. T

    Does a Magnetic Moment μ exist for any closed current loop?

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  19. E

    The magnetic field induced by a current loop

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  20. DrPapper

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  21. S

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  22. D

    Magnetic field at the centre of a circular current loop

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  23. H

    Prove that the torque of any current loop is m X B

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  24. I

    Magnetic Force from Current Loops: Relativistic Treatment

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  25. K

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  26. ognik

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  27. W

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  28. D

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  29. A

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  30. LydiaAC

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  31. .Scott

    Current Loop equivalent to Earth's Magnetic Field

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  32. G

    Circular current Loop I don't understand

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  33. B

    Magnetic field of a current loop

    i know that a current loop creates some kind of a short bar magnet , but how ? i mean in a short bar magnet , the magnetic field leaves the north pole and goes towards the south pole Of the MAGNET itself , but in the case of the solenoid or a coil , it just looks as if the magnetic field...
  34. Y

    Question on derivation of potential of a small current loop

    The vector magnetic potential is given \vec A=\frac{\mu I}{4\pi}\oint\frac{e^{-j\beta R_1}}{R_1}dl' After a few steps, the equation becomes: \vec A=\frac{\mu I}{4\pi}e^{-j \beta R}\left[ (1+j\betaR)\oint\frac{dl'}{R_1}-j\beta\oint dl'\right] The Book claim the second integral obviously...
  35. P

    Current Loop in a nonuniform magnetic field

    Homework Statement A nonuniform magnetic field exerts a net force on a current loop of radius R. The figure shows a magnetic field that is diverging from the end of a bar magnet. The magnetic field B at the position of the current loop makes an angle θ with respect to the vertical, as the...
  36. Z

    Outward force on current loop (Ampere's Force Law)

    Hi, I'm trying to calculate the outward force on a loop of wire carrying a current, radially from the center to the perimeter. I found the formula for the force between two parallel wires: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html F/L = u0*I1*I2/(2*pi*r) And the...
  37. N

    Current loop rotating to give magnetic moment

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  38. P

    Boosting a Current Loop: Effects on Current Density and Charge Distribution

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  39. B

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  40. S

    Can Green's Theorem Simplify Calculations of Magnetic Force in Uniform Fields?

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  41. A

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  42. C

    Magnetic moment of a current loop.

    Hello, calculating the magnetic moment of a current loop is trivial, but I want to do it with the general formula \vec m = \frac{1}2 \int \vec r \times \vec J(\vec r) d^3\vec r The only thing which is stopping me is to find a good argument on why \frac{1}{2}\int \vec r d\vec r = \vec A where...
  43. N

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  44. T

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  45. S

    What is the maximum torque on a current loop in a magnetic field?

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  46. C

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    I was reasoning about this matter and i found myself asking a question ... i tried to search the answer in quite a number of books (mainly Physics_For_Scientists_And_Engineers_6_Ed._By_Serway_And_Jewett and and Physics_by_James_S_Walker) but no way ... all the information i found are related to...
  47. S

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  48. jegues

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  49. C

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  50. S

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    Homework Statement Consider a long wire running in the vertical direction with a rectangular loop of wire beside it as shown. Now suppose that a constant current, I, flows upward along the long wire, and the same magnitude current, I, flows clockwise in the loop. As viewed from the top...
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