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Questions tagged [transformer]

A transformer couples two or more AC signals through a magnetic field. Often used as galvanic isolation and to transform one AC voltage to another.

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Proof that Delta and Y transformer have the same power?

I'm trying to proove that a Delta and Y transformer both have the same power. Somewhere I must get wrong in my process... I have a reading in voltage and current in a Star transformer: 600 V line-...
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In the equivalent circuit of transformer is the shut branch placed before or after the winding impedances in the primary?

I read a couple of books on transformers. A few have drawn the equivalent circuit with the shut branch placed before winding impedance while opposite was done in others. Which one is right?
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Using Multiple Taps on Transformer with Shared 0V

I have a multiple winding transformer and I need to know if I can use the 0V tap for the taps on the same winding. So the transformer is 320-0-60-320, and I need to combine the 320-0-320 into a full ...
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How to find a correction factor of instruments (wattmeter, multimeter)?

I'm interested in measuring the hysteresis loss and copper loss of a power transformer, here you can see my circuit: The internal resistance of the wattmeter and the multimeter (right hand side) is ...
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Need help with transformer

I have one transformer. Primary 230V and two secondaries 14V/3A, 15V/3A and ground between them. I am curious can I use that transformer as center tap transformer. Here is the picture: I know I can ...
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Location of secondary winding on long rod core transformer with full length primary winding

On a Rod iron Core transformer or Induction coil pair, if the primary is wound 1 layer deep from end to end of the core, say a 10 cm long coil from end to end, and the secondary is 1 layer and only 2 ...
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Transformer safety concern

I have a a transformer for my speaker (230VAC -> 9VAC). The primary of the transformer is basically a coil. Is it not dangerous to pull out the transformer from the outlet? I know that in coils if ...
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Floating secondaries in Isolation Transformers [on hold]

I connected my TV, CCTV, modems, and room appliances to a strip that is connected to the secondary of the isolation transformer without any grounding (at the isolated secondary side). This is after I ...
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Searching for a transformer for the power board of an Equipe 2400 studio blitz Power/controller

This is for a photographer friend, feel it would just be too bad to let this beautiful equpiment stay in the closet because of, as far as I can tell, one blown transformer. The unit is made by Bowens ...
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1answer
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How to understand this simple voice-over-laser circuit

The Sci-Toys project A simple laser communicator shows a surprisingly simple way to send an audio signal over a laser pointer. A transformer AC-couples an audio signal directly into the DC supply to ...
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What is the purpose of this transformer winding in the following SMPS schematic?

I am trying to understand how the following PC switched mode power supply works : The way it works in general is OK. What is not clear to me is what is the purpose of the following part in red : ...
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Transformer: Number of turns om primary winding

I'm researching electromagnetism for a guitaramp project. I would like to experiment with different homemade transformers. Find myself stuck trying to get a grip on the effect of the number of turns ...
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LT bus duct short circuit

Last week we faced serious problem at 2000 KVA Transformer LT side, i.e. LT side aluminum bus duct was fired with heavy noise and smoke & transformer oil was came out from pressure valve (that ...
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Transformer back emf feedback

I want to build my own autotransformer. In an autotransformer Does current flow from source to load because it's demanding it via direct conduction just like in DC? Or Is it due to back-emf that ...
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Power Transformer: 110V and 220V input, with two 15V outputs 180 degrees out of phase

I have never designed a power supply before and have a few questions and would appreciate any help. Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center ...
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Finding the specific Turn Ratio of a Transformer

I'm finding the turn ratio for a Hammond 166G28 28VCT transformer. I already had calculated the voltages for the Primary and for the Secondary and I divided them and got 3:1 ratio for the outer loop (...
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Using a residual current device when there is an isolation transformer

In a system, currently there is no circuit breaker and RCD, but there is an isolation transformer as in the diagram below: simulate this circuit – Schematic created using CircuitLab As you see ...
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Is there a range for an isolation transformer's common mode rejection frequency?

Below shows use of an isolation transformer in a system: (taken from this site) At C(right after the isolation transformer) the waveform is cleaner comparing to A and B. What frequency of ...
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Is there back EMF in an induction motor?

I noticed that in deriving the equivalent circuit for an induction motor in the rotor component, that a "variable" resistance was introduced. This really confused me as I didn't understand how power ...
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108 views

Short-circuiting the primary coil of a transformer to keep it warm

I saw this problem somewhere and I wanted to give it a try, but the numbers I've got seem to be pretty outlying. We have a 25kV / 4160V transformer which is out of circuit for now. To protect it ...
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2answers
48 views

Finding an Ethernet transformer when I have it's characteristics

I am using the Novatel OEM729 board for a project, and I need to implement Ethernet in the project. According to the Novatel OEM7 manual, page 48, the OEM729 does not have Ethernet magnetics, so I ...
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Is this transformer suitable for a tesla coil?

I can get my hands on this transformer for pretty cheap, As user DerStrom8 told me in a previous question, solid state transformers will not work, and big heavy one with built in protections may not ...
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Would a transformer protect a 24V digital flow meter if it received 48V? [migrated]

I purchased a new water softener for the house. It has a digital flow metering device. It worked great for a few days and then stopped working. Long story short, I finally figured out that the outlet ...
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1answer
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Choosing the right transformer to replace batteries?

I have an idea for a hack I'd like to build, but I need some help figuring out the right transformer. Let me know if there's a better place to post this sort of request. I have some exterior LED path ...
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1answer
56 views

DIY transformer (toroid) waveform

Update Ok, it may be related to the adhesive I'm using to glue the toroids on the 3D prints.. I'll wait till tomorrow for it to cure and test again.. I'm trying to build a portable/battery ...
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Power transformer impedance

I was wondering if there are any refernces pertaining to the impedance and resistance of generator step up transformers. I have different transformers ranging from 500 to 115 kV on the HV side and 9 ...
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1answer
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How do I find the inputs/outputs of an unlabeled transformer?

I’ve been trying to wire a transformer according to this schematic. but nothing is labeled on the actual transformer. There only only colored wires. On the primary side, the Blue and White wire show ...
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2answers
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Understanding transformer datasheets

I came across this transformer, and there are a few points of the datasheet that seem unclear to me. I can't seem to find any references for what exactly they refer to, so I'll ask here: Where the ...
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2answers
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How to calculate secondary winding max current output?

I have removed a UPS transformer. It is a Class B Viking transformer. Its primary side has 4 wires coloured black, green, blue and yellow. I found resistance as follows- 1. Black to Green - 17 ohm 2. ...
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1answer
107 views

Is it possible to realize an 1:16 impedance ratio Transmission Line Transformer on a single core?

I would like to build a wideband amplifier with a 1:16 impedance ratio Transmission Line Transformer (TLT) at the output. The input port of the TLT accepts a differential signal and provides a ...
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1answer
47 views

Even vs Uneven Magnetic Field Cancellation in Toroidal Transformers

If the secondary winding of the 230v-115v Step Down Toroidal Transformers have multiple separate ends and you are only tapping a portion, would there be uneven magnetic field cancellation? See for a ...
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1answer
26 views

Flyback converter primary and secondary sides power calculation

The problem is as below. Input DC voltage is at 12V, transformer inductances are: Lp = 60uH, Ls = 240uH, switching behaviour is controlled by a single NMOS with switching frequency at 60kHz. For ...
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1answer
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Magnetic Field of Toroidal Transformers

Who owned Toroidal Isolation Transformers like this: http://www.hammondmfg.com/289T.htm Do you have a gaussmeter (or any magnetic field meter like the following)? How low did you measure the ...
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Flux Transfer of Current also involved in Autotransformer?

In Isolated Transformer, the primary and secondary are separated yet when there is a demand for current in the secondary, the primary can produce current and transfer it via fluxes. I understood this ...
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321 views

Transformer Inefficiency and Heat

If a transformer has efficiency of 96%. It means for a 500W capacity and load, the input would be 520W, output 500W so 20W would be emitted as heat. If load is 250W, then input would be 260W and 10 ...
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Understanding a switched-mode power supply datasheet

I'm trying to make an AC/DC converter (230V AC to 5V DC). As part of this converter, for the first stage, I've decided to use a switched-mode power supply like https://www.digikey.com/product-detail/...
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Can power transformers be used with higher voltages?

I purchased a Japanese transformer for a project I’m doing. It runs on 100VAC, not 120V, something I overlooked. Doing a quick search, Japan seems to use both 50/60Hz, based on the region. It’s 30 ...
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1answer
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How to plot input reflection coefficient in dB scale using Matlab

So I have a problem that asks to plot the input reflection coefficient of a transformer in dB scale between 0.5 GHz and 4 GHz using Matlab. Here is the code I have thus far, it is plotting in ...
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1answer
25 views

Line - Line voltage with different phase angles, amplitudes and frequencies?

I know that the mathematical equation for the calculation of Line - Line voltage with same frequency, same Phase angle, same Voltage of 3 lines from the same generator. now, i want to know ...
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Transformer magnetizing inductance

I am learning about transformers and in the equivalent circuit the magnetizing inductance of the excitation branch is supposed to represent the current needed to "set up" the flux in the core due to ...
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1answer
79 views

Tesla coil - my primary circuit doesn't work

I would like to make a Tesla coil, so I bought a 10 kV 120 W 30 mA neon sign transformer from Aliexpress. First potential problem, while playing with it, I noticed that when it stops ...
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Switching Multi-Tap Transformer based on Input signal

Working on a project where the goal is to have changing voltage rails for a audio amplifier circuit. The approach that I am taking is the use of a multi tap transformer with different voltage values ...
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Designing a constant current pulse circuit

I'm looking for help designing a constant current pulse through a variable load impedance of 10-100k (R4). The ideal response is shown below. This waveform was measured from an off the shelf ...
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1answer
25 views

High energy efficiency through transformers

We are about to build a large facility, using lots of electricity. The facility is being built in module form, which are copies of one another. We are unsure of whether the energy efficiency will be ...
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1answer
43 views

Differential equations for a transformer

I would like to set up differential equations (please, no phasors in answers) for the circuit below: So far I have two equations: where I assume perfect magnetic coupling (so I treat M as a known ...
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1answer
56 views

Why Rod Core ignition coil in cars instead of E-I core or toroid core?

Why use a Rod Core ignition coil in cars instead of E-I core or toroid core? It appears the Rod Core coil in an automobile is just a Step-Up transformer. Why do car manufacturers us a ROD CORE? Is ...
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Help me fine what kind of Transformer this is

Can you help me find what kind of transformer this is? I'm having a hard time looking it up based on the numbers. It came off a Kenmore 220V stove
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1answer
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How is power out one side of 220 only - Problem is with incoming 3-phase. But how?

[EDIT] Can someone who understands what I wrote explain this? [EDIT 2] Sorry I didn't say I'm in the USA, the power is 110/220vac 60Hz. The input to the main power transformer is 3-phase, underground,...
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What Design is this Voltage Regulator (Is it a buck boost type)?

This voltage regular was designed by a new electronics graduate locally 20 years ago and it was not commercially produced (only privately sold) and discontinued. I need to know what kind of design it ...
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1answer
82 views

How to reduce transformer secondary voltage?

Trying to make a bench power supply. What would be a cheap easy way to reduce voltage (to protect the series pass transistor)? 3 Amp transformer has these terminals 12-6-0-6-12. No load voltage is 33 ...