What is Transfomer: Definition and 16 Discussions

A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any one coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil.
Transformers are most commonly used for increasing low AC voltages at high current (a step-up transformer) or decreasing high AC voltages at low current (a step-down transformer) in electric power applications, and for coupling the stages of signal-processing circuits. Transformers can also be used for isolation, where the voltage in equals the voltage out, with separate coils not electrically bonded to one another.
Since the invention of the first constant-potential transformer in 1885, transformers have become essential for the transmission, distribution, and utilization of alternating current electric power. A wide range of transformer designs is encountered in electronic and electric power applications. Transformers range in size from RF transformers less than a cubic centimeter in volume, to units weighing hundreds of tons used to interconnect the power grid.

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  1. L

    Transformers in a circuit, interpreting the label

    Hi hi, I was trying to use a transformer, that typical transformer that we have in house for a project, but then I notice something, well all this can be just a misunderstand from me. Actually a transformer have a voltage and a current, at least that is what it says the labels, "18V and 3A" for...
  2. Peter Alexander

    Understanding Transformer Phasor Diagrams: A Step-by-Step Guide

    Hello everyone! I'm currently studying transformers and a task related to phasor diagrams shows up. I'm having lots of problems with comprehension of the subject, so I'd like to ask for some help. I don't understand how the phasor diagram given as a solution could possibly be drawn out of the...
  3. C

    Engineering Simple transformer circuit with 3 resistors

    Homework Statement 2. Homework Equations [/B] V1N2=V2N1 I1N1=I2N2 The Attempt at a Solution For a part[/B] I try to draw 3 mesh but I cannot write down the equation. Can someone help me out?
  4. Muhammad Danish

    Calculating Current in Primary Coil: Where Does P = V^2/R Formula Come In?

    Homework Statement Homework Equations How will we calculate the current in primary coil? The Attempt at a Solution The current in the secondary coil will be 2 Amperes by I = V/R. So in the primary coil by using ratio proportion method, the current in the primary coil will be 5 Amperes. But...
  5. S

    Short Circuit Current on 161kv line

    I work at a electric arc furnace. We measure a lot of items on our furnace and found that some weeks we preform well and other we do not (kwh/ton). With everything else being equal i believe that the utility's available short circuit current is affecting this. The utility feeds our substation...
  6. EddieP

    B Transformer core saturation- is this core saturating?

    Please excuse me if this is a very basic question, but I am just hoping someone can enlighten me on something. I am using the program FEMM to simulate a transformer. Unfortunately, I am unable to find data on the BH Curve of the material I’m using for the core, and I am worried that my...
  7. EddieP

    How does the core size affect an Inductor's efficiency?

    Hello, I am wondering if anyone can help me with the following question. I want to find out how the size of the core in an inductor influences the current induced in the secondary coil, and whether a smaller core is more efficient if efficiency is defined as inducing the highest current in the...
  8. U

    Why the efficiency of air core transformer changes (up and down)

    The graph below shows the efficiency of an AIR CORE transformer at different voltages (from MAINS). At low voltages, it has high efficiency and gets lowers because of high magnetising current causing heat loss. But why is it higher at some points again? I do not understand this pattern. Please...
  9. entity314

    Frequency appears to have to effect on hysteresis

    This question is primarily regarding transformers, particularly the impact frequency has on hysteresis loss. Given hysteresis loss = η×Bmax×f×V and Bmax = (V ×〖10〗^ 8)/(√2 π×f×N×A) This means that hysteresis loss = η (V ×〖10〗^8)/(√2 π×f×N×A) fV = (η ×〖10〗^8)/(√2 π×N×A) V^2 And as such...
  10. A

    Calculating core losses in transformers

    If i have a transformer, and i need to calculate the core losses using this approximate equivalent circuit, according to the lectures ( taking an introduction to electrical machines course in college) the Pc ( power lost in core) = (V1)^2/Gc, but the professor clearly stated that the core losses...
  11. loki4000

    Quick question about transformer circuit

    Homework Statement Can someone inform me wheher my solution is correct? Homework Equations V1 = E2 * (10^-3)/2*(10^-3) = 0.001 V2 = E1 Ra = (R2+R3) = 0.02 Rb = R1 = 30 n = (1/100) n^2 = (1/100)^2 The Attempt at a Solution I1 = (V'1 - V2)/(Ra'+Rb) I1 = (0.001/n - 230)/(0.02/n^2 + 30)...
  12. S

    Can I use two AC TRs with ONE neutral at sec. and prim.?

    The situation: I have one BMS (Building Management System) controller supplied from TR1 (220Vac to 24Vac transformer) and provides an analog control signal (0-10VDC) with the (-) of that DC being the same as the Neutral of the controller (from TR1) and should control a valve actuator. The...
  13. ernd59

    AC current / volatge with a mosfet in Ltspice

    Hi, my Voltage Multiplier Simulation does not work properly the first transformer is working just fine, the second one does not really seems to work, for the second transformer i tried to creat AC current with a mosfet, but i think I am doing it wrong :/, can you give me some tips how to...
  14. Y

    Generate electrical energy from vibrating transformers

    Hey guys, how are you? I just have an idea but can't figure it out how to solve it. Is it possible to generate electrical energy from a (high power) transformer vibration using piezoelectrics?
  15. eee_engin33r

    System Loss In Terms of I why not V?

    We all know that the system loss in transmission line is i^2R. So, in order to reduce the loss we diminish the current flow through the line by means of transformer. My question is i can also calculate system loss by the formula v^2/R where v is the potential across transmission line. So...
  16. F

    Not sure what kind of transfomer I should use

    Not sure what kind of transfomer I should use... Hello. I am trying to build a high-voltage DC transformer for a project (using a disruptor). I will be using a battery for the power (probably a 9v or 12v). I have done some reading about the different kinds of transformers used, and I am...