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.
A changing current in a transformer primary produces a changing magnetic field, which induces a voltage in the secondary (correct?), but if no circuits are closed on the secondary, there's no current in the secondary (and therefore primary as well). So how is this voltage induced?
I am not sure if I should use the word 'current' or 'charge' but my question is whether, in a typical U.S. residential 120/240 split phase system, is the local transformer always the source to which current (charge?) must return? Or can it bypass and go direct to other PoCo elements/generators...
Here is the circuit...
Here is my work so far in cadence (I haven't put in values for other components in because the moment I saw the dot convention I started trying to figure that out).
Where I'm at
-There apparently isn't a way in Cadence Virtuoso (the program my class uses) to change the...
I am in a team of designing a 33KV potential transformer. We done secondary turn as 75 and primary turns as 15000 with core cross sectional area of 5000 sq.mm. As per IS standard we need to maintain a accuracy class of 0.2 at 50VA burden but we can't able to achieve it. Someone please help us to...
I am trying to create a receiver for a personal project I am working on. This is the RF amplifier that I was given by a book I am following. How does this circuit work? Usually for a BJT amplifier I find the DC bias point and then use the small signal model after I bias the circuit? I understand...
So I was watching this video containing DIY experiments on electromagnetic induction .
At minute 4:45, the dude pretty much creates a transformer without using an iron core.
He runs 30-50 kHz AC in a coil (forming the primary circuit) and then brings another coil with its ends attached to a...
This is the first part of the problem, which I solved.
Now to the second part which I can't manage to find the equations I need to use.
Problem:
This plant is connected to a 20/0.4 kV transformer of 250 kVA power, through an XP00-A cable (4x150 mm2, IN=300 A, Z1=0.26 Ω/km).
a) Calculate...
I can't seem to find a transformer that simply converts a low voltage 9V-12VAC to a center tapped output to get +/- 9v/12VDC. It seems all power transformers have a 120VAC input voltage and the lower voltage transformers are designed for high frequency switching. What is a low voltage to low...
It is a common center-tap transformer which is electrically demonstrated as in figure (ideal one);
In my opinion, open circuit and short circuit tests cannot be applied directly. How can I place secondary reactances ? And how can I test its all parameters in laboratory ?
I would like to make a program that produces a 2D heat map showing the magnitude of the magnetic field produced by a finite length solenoid. The heat map would show the field strength along the radial and axial directions of the solenoid.
I plan to divide the conductor into "infinitessimally"...
Let's assume a 2:1 transformer which has a 100V Source connected on the primary circuit and has no/negligible resistance, on the secondary circuit a 5 Ohms resistor is connected. Using the 'Impedance Transfer/Reflection' method, the primary circuit would act as if there was a 25 Ohms resistor...
1. Homework Statement
A 415V to 11 kV transformer has a rating of 200 kVA. The winding resistance and leakage reactance when referred to the primary are 0.014 Ω and 0.057 Ω respectively.
(a) Determine the % regulation of the transformer at 0.8 power factor lagging.
(b) In designing a...
Homework Statement
Ok I have the following circuit and data (when the subscript is "ef" it means "rms" values):
I am asked to determine the parameters of the transformer r1 L11, L22 and LM with the given experimental data.
Homework Equations
3. The Attempt at a Solution [/B]
I had no...
<Moderator's note: Moved from a technical forum and thus no template.>
Hi all, I have attempted this question but have a few queries on how transformers work, and what the dot notation represents.
(a) The flux would be clockwise around the iron core.
(b) This is the question where it gets a...
This is a 12-0-12 transformer that I intend to use in my circuit:
Why are there three wires in the secondary? One is of course the neutral (in black). Why are there two live wires?
As an additional question, can I use four 1N5408 rectifier diodes to convert the output of this transformer to...
Hello community,
I can't find an explanation for something and I thought I'd come and ask you.
I'm studying for a test I have tomorrow and I came across a problem of a three legged steel core with 400 turns on the center leg, the magnetization curve is given, the first part of the problem asks...
Hi everyone! This is my first thread :)
I've been working a bit with AC and radio, and would like to make a simple(-ish) circuit in which a 1-volt peak audio signal is stepped up to around 5 volts with a transformer, and is fed into a crystal oscillator to make a crude-but-effective AM...
Thank you for reading my post.
I was watching the video this video on transformers and saw an amazing demo:
From 4:00-5:20 the guy does an experiment where he has a simple transformer circuit set up:
On the primary side of the transformer he has an AC power supply, and a lightbulb.
On the...
I would like to know if there are any general equations (such as the AC transformer equations) that describe a switch mode DC transformer. By this i mean a constant frequency DC signal (50% duty cycle) that ranges from 0V to some max voltage on the primary coil and outputs some higher voltage on...
I want to program a little power grid game and have the problem of connecting things via transformers. Imagine the following setup:
You can see the AC voltage sources as generators (or together with the resistor as a "consumer", if the amplitude is 0).
What I need to figure out are the...
I have a transformer chamber with 2 doors.
What I have to do-
If any of the door is opened, this should happen-
1. 2 CFL inside transformer chamber should start
2. Simultaneously, a buzzer/hooter should be ON.
3. After opening the door, I should have option to reset the hooter.
how do I do it?
Homework Statement
I am working on the following problem:
And ideal single phase transformer 240V/2880V is supplied with a 240V source via a resistance cable of 3ohm. If we connect a R=720ohm resistance to this, determine the primary current and the dissipated power in R.
(I'm sorry if some...
I apologize for being somewhat scatter-brained here, I just have too many questions on this topic.
I know high-frequency transformers use ferrite cores instead of laminated silicon-steel, but what other differences are there?
Does their reactance still follow the standard formula: 2*Pi*F*L ...
I don't understand how this is possible.
This is a rather large transformer in a stereo system amplifier. The transformer is a simple step-down with 120V mains primary to a center-tapped secondary providing both 38V and 76V.
According to ohm's law, at 120V this thing should draw about 85 amps...
Hi,
Regarding transmission line booster transformer topologies I'm curious as to what would happen over all the possible permutations.
I refer you to the following:
http://top10electrical.blogspot.com.au/2015/03/booster-transformer.html
I presume that in real life the booster transformers...
I have a combined motor and screw drive (to 90 deg).
It's original purpose was to convert car windows to electric drive... my guess is that it is at least 25 years old, and made in Japan.
For scale... the width of the motor casing is 50mm (as you look at it)
I'm making a motorised turntable...
Alright It's been over a year since I've posted and received amazing help the last time I did. Now I've a question I cannot seem to find an answer to. Say you have an electrical charge and use a transformer to step up the voltage high enough to where it arcs in air. Then you have a conductive...
Hi,
Silly little question about the transformer short circuit test.
When I perform it with the secondary shorted and I get Req = Power / current2
is this Req = Rpri + Rsec?
If I measured Rpri and Rsec with a multimeter?
Thanks
Hello, I have a strange request from a client.
He has a "burn-off" which is used to burn bits of labels that are stuck onto his products, that's a bit vague, but it's all the info I have.
The request is that he wants to be able to change the voltage going through the burn-off anywhere between...
Homework Statement
A pair of power transmission lines each have 0.68-Ω resistance and carry 650 Amp. If the primary voltage of the 10:1 step-up transformer is 4.6 kV, calculate the input voltage of the step-down transformer at the other end.
Homework Equations
P=IV
V=IR
IpVp = IsVs
The...
I am trying to determine the primary magnetizing inductance + core shunt resistance of a transformer. I attached the equivalent circuit of the transformer. I left the secondary open and have an AC voltage on the primary. This causes the coupling leakage inductance and coil resistance to appear...
Hello.
Let's take a transformer picture first.
The basic equation explaining how the transformer work is the equation of Faraday's law of induction.
\begin{array}{*{20}{c}}
{{V_P} = - {N_P}\frac{{d{{\rm{\Phi }}_B}}}{{dt}}\;\;\;\;\left( 1 \right).}\\
{{V_S} = - {N_S}\frac{{d{{\rm{\Phi...
Hi.
All derivations of the (ideal) transformer equation ##\frac{U_p}{U_s}=\frac{n_p}{n_s}## use Faraday's law of induction
$$U=-n\cdot \frac{d\Phi}{dt}$$
for primary and secondary and equate the change of flux ##\frac{d\Phi}{dt}##.
Until now, in my textbooks it was always like this: Electrical...
≪ mod note: thread moved from technical forum so template is missing ≫
Homework Statement
Relate secondary current to primary voltage in a single-phase transformer having resistive load for non-ideal situation.
Homework Equations
KVL, Voltage across resistor and inductor, ac voltage as a sine...
In a transformer, let's say we have:
I1, I2 - currents through the primary and secondary winding
V1, V2 - voltages
N1, N2 - number of turns
F1, F2 - magnetic fluxes through core, produced by the currents I1 and I2 (they are opposing...)
R - the reluctance of the core
We have V1/V2 = N1/N2...
If If you have a compressor designed for US 60 HZ 230 V what are the risks with applying it in 220 V 50 HZ ?
I understand there will be a ~20% derate in power but are there any safety or failure concerns ? would the lifespan of equipment change?
Do I need a transformer ? This equipment...
In a transformers output, is it the current that is fixed or the voltage?
I have been trying to resisitively heat some tungsten foil and I am stuck at trying to find out the amount of current I need in my transformers output. The problem I am facing is that I know that the tungsten resistivity...
Hey... how's it going?
I've built a step down box to run 110 VAC appliances off incoming 240 VAC (Malaysia). The only components in the box are a cooling fan (240 V) and a great big transformer. It's a single phase 30A output aluminium cored 240V->110V 50 Hz transformer that weighs about 25 kg...
Hi, I should know better, but I'm having a mental blank. I was just wondering, if you're doing something using non-linear components on the mains, could be anything, maybe bucking to make a DC supply, whatever.
Is it common practice to use an isolation transformer between mains and the...
Hi all,
I am designing a three phase 11000/433 Volts Delta/Star 50 Hertz transformer in Ansys Maxwell. It has 792 turns in 6 layers on HV side (132 turns per layer) and 18 turns in 2 layers (9 turns per layer). The resistance as I have calculated is 0.1325 ohms per phase of HV winding and 5.57...
In all tutorials I have read on tesla coils, they have said to use a capacitor spark-gap configuration, to create a tank circuit. I want to know exactly what this means, and what is its purpose. I am not going to build a Tesla coil, I am nearly just interested in the science of it.
My goal is to program a FDM simulation of a transformer. So, we have the coupled inductor model to start with ...
However, if L1 = 1, L2 = 9, and coupling is perfect then M = sqrt(1*9) = 3 and L1 - M = -2.
So, this seems problematical to me. Also, if I try to simulate this model using SPICE...
The thread name is probably misleading, but I just want to make sure I'm clear in that: Are the only two problems caused by leakage inductance (stray magnetic flux causing imperfect mutual coupling) in a transformer, that of;
- poorer voltage regulation &
- EMI noise on other equipment
(?)...
Hello.
Please see the attached picture first.
For typical battery (nothing but capacitor), current direction is clear as electrons can't not flow across the two plates in battery so they only choose wire as a path from cathode to anode.
But in transformer (+ and - sign represents voltage at...
Hi. My colleagues and I are doing a research on transformers (single-phase) and we stumbled across the following equations involving hysteresis and eddy current losses:
Wh = ηBmaxxfV
where Wh = hysteresis losses
η = Steinmetz hysteresis constant
Bmax = maximum flux density
x = constant...
Has anyone considered the iron core of a transformer to act as a transmission line or waveguide, where it conveys energy from primary to secondary? The core seems to resemble a "magnetic version" of the single wire Goubau line.