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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Correctly Using the Chan model in LTSpice

I am trying to use the Chan model to better simulate a transformer in my design. When I am making an equivalent transformer circuit, where does the Chan inductor go? On the LTWiki it is implied ...
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Using a 575 V to 220 V step-down transformer to power a 3 hp, 575 V motor with a 220 V VFD

I have a uniquely designed motor for a milling machine (expensive to replace and to purchase at a lower voltage). What I want to do is purchase a 575 V primary, 220 V secondary 3p used transformer, ...
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124 views

Two port network and transformer?

How the circuit and equivalent circuit of a Transformer are derived? Does two port network help us in this regard to find the circuit and equivalent circuit of the transformer? Secondly I need to know ...
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How to read a transformer data sheet?

I have been trying to understand this datasheet but I think I am missing some core knowledge. I just want to know what the inductance of the primary is when the secondary is unloaded (I am using the ...
606 views

Parasitic capacitance of planar pcb coil

As an experiment I attempted to make a planar PCB coil as shown below: Showing parts of a single layer for presenting detail. Together with a an EE ferrite core it generated 85mH of inductance as ...
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153 views

Eliminate reflections on pulse signal transformer

I am trying to isolate an RLC ringdown signal via an RF signal transformer but I'm having trouble maintaining the signal integrity through the transformer. Below is the simple schematic describing my ...
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What defines the maximum primary current of a (sensor-only) current transformer?

Take the Coilcraft CS1200L for example, which states the sensed current maximum is 35 A. This limit doesn't seem to be defined by the wire size which can fit through the hole (5 mm) as you can pass > ...
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429 views

Grounding balanced secondary isolation transformer for EMI suppression

simulate this circuit – Schematic created using CircuitLab Which is the best secondary connection to clean the main line power from EMI, line noise and HF harmonics by using an isolation 1:1 ...
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717 views

Piezoelectric transducer impedance and phase measurement

I have a circuit comprising of LT1210 current feedback amplifier (supply voltage = +/-15V, gain = 4) and its output is connected to a transformer (RM10 N97) with N=16.6 (150/9) which is further ...
920 views

What do these numbers mean on a transformer schematic?

What does the .7, .6, 1, .5, ...
• 321
2k views

Balun single-ended 50 Ω to LVDS 100 Ω conversion

I have an LVDS differential 100 Ω signal which I want to convert to a single-ended 50 Ω signal. I want to use a BALUN for this conversion. What kind of BALUN should I use here? Some BALUNs have a 1:1 ...
• 149
391 views

What will be the effect of putting a single phase load on an open delta transformer secondary?

Suppose I have an open delta transformer, 240 line to line secondary. I have a single phase constant power load I want to apply. I could apply it across either of the 'closed' phases and load that one ...
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Derivation of formula for transformer maximum power

How can I derive the formula for the maximum power handling of a HF transformer with ferrite core utilized in a selected converter topology (push-pull for me). The formulas I have seen so far utilize: ...
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Is this a safe way to use isolation transformer to mitigate neutral to ground voltage?

I work with a TN-S system wiring. Main three phase transformer secondary is in Y configuration. A single-phase lab instrument equipment installation requires less than 1 V for neutral to ground. We ...
91 views

Modified microwave oven transformer for step up, is it viable?

So basically I need a 600V output from a 12V supply. I have a pulsed DC voltage (square wave) on the primary and I'm using the old MOT primary as the new secondary. I've calculated the secondary (old ...
• 133
47 views

Current transformer design guideline

I want to design current transformers with two secondary windings (one for control loop and another for monitoring.) It will be used in DC-DC converter. What are the guidelines to be followed for the ...
92 views

DC-DC flyback transformer (SMT)

I am building a flyback DC-DC converter for a school project and am new to soldering and power electronics. I want to prototype the design on a breadboard first, now that I have the design equations ...
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115 views

What is the function of the capacitors and MOV on the outlet receptacle of this isolation transformer?

I recently purchase a used Tripp-Lite IS250 isolation transformer off of eBay. Here is the datasheet. It's a fairly open secret that these are not true isolation transformers suitable for a tech bench,...
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How to solve the equivalent circuit of the induction motor?

Let's say I have below given equivalent circuit of the induction motor. The parameters $R_S$, $R_{Fe}$, $R_{load}$, $X_M=2\pi\cdot f\cdot L_M$ and $X_L=2\pi\cdot f\cdot L_L$ are known and ...
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How to calculate the parameters of the equivalent circuit from the no-load measurement of the induction motor?

I would like to determine the values of the parameters of the magnetizing branch of the equivalent circuit of the induction motor based on the no-load measurement. Based on the Electric Motor Control ...
• 1,061
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Delta/Scott-wye/Scott?

I’m a level two electrician so we haven’t been taught about 3 phase even though I work with it all the time and I think I have an ok understanding. I can’t find any information on this transformer and ...
64 views

Sizing a Transformer

I'm trying to spec out a 3-Phase transformer for a project i'm working on, I know that the max load is going to be 40.3kW & I know that the total FLA is 82 Amps operating at 480V @ 60hz, but I do ...
55 views

In a forward converter, why do we need a separate controller for secondary side switches?

LT8311 IC is said to be a synchronous controller IC for a forward controller. Why do we need a separate controller at secondary side as the PWM pulses of primary side should dictate the synchronous ...
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Choosing a transformer for 120V->240V AC step-up for low current (<1 W)?

I've got a device (microcontroller-based energy monitor, https://shelly.cloud/knowledge-base/devices/shelly-em/) which I'm using to measure energy consumption of 240V split-phase devices (motors). ...
286 views

Ideal Transformer Currents Relationship

I'm currently quite confused with the relationship of the currents for an ideal transformer when it overlaps with multiple mesh currents. It was defined that for: \frac{\bf I_2}{\bf I_1}=\frac{1}{n}...
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What is the effective value of the current of the voltage generator?

I need help with this task, if anyone had a similar problem it would help me. The task is: A voltage generator is connected to the primary of an ideal transformer, transformation ratio n rms values ​​...
157 views

Electric grid power transformer winding: If it is milliohms, why does 9V DMM show infinite ohms?

When testing large MVA power transformers, like 66kV to 16kV, the winding resistance in DC ohms is milliohms. It takes a high current supply to do this, then the V is measured across the winding to ...
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wave form of the diode current of a rectifier circuit and difference between the transformer and the AC source

So I have two questions I hope you would answer it, the first one is about how would the current Id of this circuits be? I mean his waveform. and my second question is these two circuits who are in ...
708 views

How to ground a flyback transformer?

I designed a 50,000 volt power supply, that I am having problems with on grounding the HV side of the output. The HV appears to be injecting HV into my logic sections through the ground, damaging the ...
95 views

How do I find Vs in this circuit with a 2:1 ideal transformer?

How do I find Vs given that V0(to the left) is 10L30degrees? I started by finding that the current on the 10 ohm resistor is 1L30 degrees, and then using kirchoff's law, the current on the tranformer ...
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Comparing inductances from LCR measurements and FEMM simulations of a simple transformer

I am trying to compare the results from a simple transformer using two identical Wurth Elektronik inductors (Reference 760308102308, datasheet attached). I measured the inductance with an LCR while ...
315 views

Relation between primary current and secondary currents in a transformer with multiple outputs

This applies for a flyback converter working in DCM. Here is what the following document (https://www.infineon.com/dgdl/an-1024.pdf?fileId=5546d462533600a401535591115e0f6d) has : Here is what I ...
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Understanding SPICE code in Chan Transformer in LTSpice

Taken from here: http://ltwiki.org/?title=Transformers I am having trouble understanding how the Chan core is actually linking in with the coils. Does anyone understand what the SPICE code is doing ...
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What causes voltage to increase from 12V to 36V as specified?

Reference article and paragraph: Relays, Selection & Usage (Part 1) - 8 - Latching Relays ...
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Why should the primary winding of the transformer not be grounded?

I've been wondering what would happen if you grounded both star points of a Y/Y connected transformer. This shouldn't affect the voltages, so why really is it not advised to earth both the primary ...
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Which capacitor in series with resistor circuit to reduce remanence effects of transformer?

The "Comparative Analysis of Mitigation Techniques for Inrush Current of Transformer" mentions "Pre-insertions resistor with capacitor method" as an inrush mitigation technique: When circuit ...
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Joule thief modelling

I am trying to use a Joule thief circuit to harvest energy from an almost dead battery, but the references that I found on forums or in conference papers just explain how the Joule thief circuit works,...
246 views

Startup and auxiliary/station transformer power parallel to bus

This question is in regard to switchyard/electrical distribution operations in a utility power plant. During a startup, the electric distribution system is lined up so that the startup transformers ...
799 views

2 Switch Forward Converter Volt-Sec/Charge Balance

I am attempting to design a 2 switch forward converter. I understand how to do the volt-sec balance and charge balance when the converter is as shown in the ideal 2 switch forward converter below. I ...
108 views

Equipment Grounding Conductors (EGC) Behavior of Autotransformers

I'm a bit surprised why some people in the US were alarmed about using autotransformers as general appliance 240v-120v step down transformers. In Asia where we use 240v. All 240v-120v transformer ...
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784 views

Flyback Transformer - Grounding the Ferrite Core

Today I dismantled (I hope this is the correct verb) a flyback transformer. The thing that I've never seen is that one end of one of the windings is "glued" to the ferrite core (Before you ask; yes, ...
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Flux control of transformer

Can the flux (not flux density) of a transformer be controlled so as to achieve constant voltage output with varied loads? For example, increasing the flux slightly when the load is high.
43 views

Keep potential difference fixed for transformer's output

I have a source consisting of V1, R1, L1, and L2 to which my load R2 is attached: For the load, I have 10 or 100 Ohms. 1) R2 = 10 Ohms: Vrms = 315 V, irms = 32 A, P = 10 kW 2) R2 = 100 Ohms: Vrms =...
748 views

Find impedence given per unit value-transformer

I really can't wrap my head around this. Three single phase transformers are connected to create a 3 phase transformer. They all have the same nominal values : voltage conversion : 1.2kV/120 V (...
161 views

Transformer test only making sense unloaded

I have a problem in testing a transformer recovered from an old wall wart. The transformer has several secondary taps: the wall wart had a slide switch allowing the selection of four different dc ...
803 views

I'm interested in how the efficiency of a transformer changes with the power factor of the load. I know that in principle you can increase efficiency through power factor correction (i.e. making your ...
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Wiring 2 audio output transfomer secondaries in series or parallel

I want to know if wiring 2 audio output secondaries in series is doable. See problems with this schem? Would parallel be a viable alternative?
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1 vote
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accurate method of determining turns ratio of single phase transfomer

In determining the turns ratio of a single phase transfomer ,we are asked to use voltage ratio (Vp,Vs) side by side current ratio(Ip,Is). we open circuited the secondary transformer and put test ...
1 vote
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Reducing Isolation Transformer Leakage

I watched this video and wonder if its complete separation of primary and secondary coils is the normal way to wind a low-power isolation transformer (e.g., 60Hz 120V 120VA). I particularly want low ...
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Placing a comparator below a transformer

I am working on updating an older flyback design. Part of the update is adding a comparator to control a relay through a MOSFET. It's a quasi-resonant flyback so the operating frequency swings between ...