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Questions tagged [thyristor]

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0
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1answer
35 views

Why on shutdown the SCR can be compared to a power diode?

I have this as a homework question and can't seem to find the answer in my notes, book or internet. I know they will behave similarly when there is a reverse polarity on both, but the way my professor ...
0
votes
3answers
82 views

Xenon Flash thyristor trigger

I'm building a xenon flash unit with a power of 50Ws (300V 1000uF capacitor). I need to trigger it from a microcontroller. For that I use a MOC3041 to opto isolate my µC from the HV circuit and ...
0
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3answers
118 views

Why are the diodes in this circuit forward biased in spite of no current flowing through them?

Considering the following circuit, Normally in the +ve half cycle SCR1 is triggered after it takes its triggering gate pulse and then D2 becomes intrinsically forward biased so it's on and conducting ...
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0answers
33 views

Factory PFC correction

Our facility is high power (1000kVA+) But the load is very unstable. Most of the time the transformer is in question of excessive or inadequate PFC situations. The PFC controller is present, the ...
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0answers
13 views

Hooking up a stepless thyristor to a duct fan [migrated]

so I bought this fan: https://www.systemair.com/en-GB/UK/Products/fans--accessories/circular-duct-fans/circular-duct-fans/rvk/RVK-100E2-sileo-1ph230V/ which states that The fans can be speed-...
10
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1answer
241 views

What distinguishes an ordinary thyristor from a GTO thyristor?

A thyristor, I know, is a four-layer PNPN structure, with an anode on the first P section, a gate on the second P section, and a cathode on the second N section. This simple structure suggests that ...
3
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3answers
46 views

Testing a thyristor

I have a very large high voltage device that a friend asked me to take a look at. It has a bunch of BIG thyristor packages (Semikron, SKKT 106/18 E, Dual Thyristor Module, 600A 1800V). I'm testing ...
0
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1answer
44 views

Why the voltage suddenly reduces when thyristors change from forward blocking to conduction mode

As per the diagram: v-I characteristics of SCR is a graph of anode current I A on y-axis & anode to cathode Voltage plotted on x-axis v-I characteristics can be split into two parts namely ...
14
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7answers
4k views

Relays vs. thyristors: What is best for swiching 230 V lights on and off rapidly (~ 5 Hz)?

I am building my own disco/party lights. 230 V/60 W bulbs, and ideally I would like to switch them on and off at 5 Hz. I was planning on a simple setup with an Arduino controlling the lights. My ...
0
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1answer
29 views

SCR (thyristor) - Practical Dimmer Circuit

Could someone please explain the main function of the capacitor C3 connected between the gate of the thyristor (through the diac) and the cathode of the thyristor, in this Dimmer circuit schematic
0
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2answers
88 views

Negative gate SCR

I've accidentally supplied the gate of an high power phase control thyristor (Vdrm=5200V and It(rms)=6500A) with a negative current (about two times the trigger current and four times the trigger ...
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0answers
165 views

How do I set up firing angles for each thyristor in the three-phase fully controlled converter?

I am building a three-phase fully controlled bridge converter in Simulink: but I cannot seem to figure out the firing angles for each of the thyristors in the bridge.
1
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1answer
145 views

Can somebody explain how this circuit works?

I have the following circuit implemented in the control of a thyristor. I know the basic functionality of the circuit, but i need a complete description of every component. Thank you!
1
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3answers
88 views

Does Thyristor (SCR ) works for Inrush current protection?

Does a SCR ie Thyristor work for Inrush current protection in a circuit ?
0
votes
1answer
116 views

Triggering the thyristor for the single phase AC voltage controller in MATLAB

I have been trying to study the output characteristics of a thyristor based single phase AC voltage controller through the model in the picture attached. Could anyone tell me what I could do to ...
0
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1answer
421 views

Three-phase thyristor rectifier - Minimum firing angle

Why is a minimum firing angle (>0, usually 5-15°) defined for three-phase thyristor rectifier? I would like a technical explanation. Thanks
8
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1answer
236 views

Parallel RC filter on SCR gate

I came across an old circuit from work that discharges a capacitor (C1) into a step-up transformer to a low-impedance load. This event is triggered by a pulse into an SCR, whom has a parallel RC ...
0
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0answers
43 views

Thyristor Inverter fires for a moment and then it won't

As you can see in the circuit below, I have a capacitor charged at 1000V where the idea is to fire the thyristor inverter block to build three phase currents/voltages. For PLL block I'm considering a ...
0
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2answers
60 views

Why should I specify a 'pulse width' when firing a thyristor rectifier/inverter?

If I'm correct, the controller will send a gate signal to this bridge (6-pulse or 12-pulse) and even if it sends them with 1 degree of width, the thyristors must close until the current through it ...
5
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1answer
166 views

Thyristor/SCR \$i^2t\$ and \$i^2\sqrt{t}\$ Rating

I have commonly seen the \$i^2t\$ rating for fusing in a SCR datasheet. This is a helpful rating for assessing if pulses which exceed the surge current rating (Itsm) of the SCR will damage it. ...
1
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2answers
160 views

Thyristor as a traic

I have a thyristor with the connection as in this thyristor (fig 1) and i am trying to use it as a traic. Edit: I am using 3020 optoisolator and resistor value as shown in fig.2 Supply is 220V. Can ...
0
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0answers
49 views

Why output voltage of a 12-pulse rectifier oscillates with a resistive load?

I'm simulating a simple 12-pulse rectifier with just a resistive load at the output and altough I get every pulse, it seems that they are oscillating if I zoom out the signal. This is the system I ...
0
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0answers
33 views

How can I buld a scr-thyristor from a npn and pnp transistors? [duplicate]

as a scr equvalent circuit shows is there any way to make a scr from two bjt transistors
3
votes
1answer
212 views

Capacitor commutation of thyristor and DC load

In my school notes I have been given a basic thyristor circuit. I would like to breadboard a similar circuit and have some questions about choosing a suitable capacitor type and value between points P ...
0
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1answer
96 views

GTO Driver circuit

i am new to power electronics.I am working in project where input is pulsating dc and i have to control it, i try with scr but we can control only on of scr not off so in some case the cycle cut ...
1
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2answers
140 views

Inrush current switch with thyristor?

Background: I've a problem where I need to measure the inrush current of some parallel DC/DC converters in a system where the input voltage may vary between 360-600Vdc on start up. The inrush current ...
0
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2answers
159 views

Replacement Triac

I have a simple dimmer module with a busted Triac MAC97A6. I want to replace that component so that the module will work again but stores near my area don't have that specific component. One store ...
13
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2answers
3k views

Can a thyristor be built from two transistors?

Supposedly, an SCR/thyristor is just a simple, four layer PNPN semiconductor. If that's the case.. When a circuit calls for a SCR/thyristor, and there isn't one available, can it be substituted by (...
0
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1answer
79 views

Do phototriac optoisolators (e.g. MOC3021) require pulse trains?

I have a project where I need to make a microcontroller trigger an old, non-controlled, camera flash (think of discharging a capacitor through a xenon lamp). First idea was use a transistor-based ...
0
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1answer
2k views

Line Commutated Inverter

This is the circuit diagram for a Line Commutated Inverter which I came across in my power electronics book. The input and output voltage waveforms are give below: My logic says that from π to 2π,...
0
votes
1answer
393 views

Firing Anti-parallel Thyristors with continuously firing pulse-trains

Can I use two pulse trains as describe below to fire a set of anti-parallel thyristors? Is there any potential danger in this firing scheme? PS: I must use pulse train firing in my application.
0
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1answer
116 views

Main switch circuit with thyristor and bridge problem

Following circuit is a 220V touch switch from this website: http://8085projects.info/m668-based-touch-sensitive-step-dimmer-circuit.html I'm wondering how it works because the IC take its working ...
2
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2answers
519 views

IGBT-based capacitor charge transfer and thyristor-based capacitor discharge

simulate this circuit – Schematic created using CircuitLab I am designing a circuit to provide a couple of strong and fast current pulses (~1000 A, more current is better, ~100 us, half-sine) ...
3
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1answer
149 views

Help with semi-controlled full wave monophasic rectifier using MOC3011 and SCR

I'm trying to build a full wave semi-controlled rectifier with this circuit: The zero's detection is working well and I am firing the TRIAC depending on the position of the potentiometer, the ...
0
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0answers
514 views

Average output voltage of single-phase thyristor-controlled bridge converter

This question is highly related to this one but I don't find the answers satisfying. I'm a bit confused about the equation for the DC output voltage of phase-controlled bridge rectifiers. \$V_{o_{...
0
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2answers
242 views

Inner Resistance of TRIAC

Due to some problems in my project, I am curious about the inner resistance of TRIAC when it turns on. I have run some tests. The setup is just like the schematic picture. Rs is the source ...
0
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1answer
101 views

How to design individual commutation for SCRs in H Bridge configuration?

I am designing a DC drive using SCRs in H bridge(with protection circuits). Triggering is done via an optocoupler. Motor specifics:24V DC , 10 Amps Supply specifics: 24 V DC, 15 Amps(with regulation, ...
0
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1answer
65 views

Rectifier and thyristor

I'm wondering as to how a system like this: acts, when their thyristors are controlled in various ways. The converters are simple enough, but I'm wondering how the graph made around the voltage ...
0
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1answer
4k views

Speed control of 3 phase induction motor using thyristor

I am working on project of controlling speed of 3 phase induction motor. To control the speed of motor I am using thyristor TYN16-600CT. As I am searching for ...
0
votes
1answer
138 views

Thyristor latching problem

I am attempting to make a circuit which triggers a 555 astable. The input is one of those IR beam break sensors with the output of the phototransistor going to a NOT gate and the output of that is ...
0
votes
1answer
1k views

How do I find the firing angle of SCR practically? [closed]

Our teacher told us to find out the time period and then multiply it by 18.Then 180-(∆t*18) gives firing angle.Why 18 as a multiplier?
0
votes
1answer
54 views

Thyristor in a choppercircuit

I've the following kown values: Switching on loss is \$\text{E}_\text{on}\space\text{J}\$ in \$t_\text{on}=\tau_\text{on}\space\text{s}\$ Switching off loss is \$\text{E}_\text{off}\space\text{J}\$ ...
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2answers
296 views

Triggering a Thyristor

I am trying to model a thyristor DC switch but I am having problems with properly turning "ON" the SCR that is used as the switch. I am using a 2N1595 SCR and I've looked at its datasheet and it seems ...
0
votes
1answer
301 views

PSpice Thyristor DC Switch

So I am trying to model a thyristor switching circuit but the results I get are as if the SCR that is used as a switch lets the current go through even though the gate current hasn't been applied yet. ...
2
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2answers
208 views

Replacement for tube-based trigger switch (Thyratron) in high-voltage supply

A now-deleted question asked whether it's possible to replace the trigger in a specific application (laser supply, source here): fig 26 http://pe2bz.philpem.me.uk/Lights/-%20Laser/Info-902-...
0
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1answer
556 views

LTSpice Simulation Problem - Controlled Rectifier Single Phase Dual Converter

So I am having problems simulating a Single Phase AC/DC Dual Converter on LTSpice. At the first converter I am getting the perfect output but when I take the voltage probe from the second converter ...
0
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3answers
369 views

Minimum current of a sensitive gate SCR

i have a few 2N5064 SCR that are puzzling me. No matter how many hundreds of thousands of ohms i put between their gates and a 3.2V battery source, it always starts to conduct. I even put a 10 V zener ...
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2answers
2k views

SCR Gate to negative

Is a short circuit that occurs for as long as an instance safe? In the following schematic done from here, I have a silicon controlled rectifier that is used as a latch (the circuit simulation doesn'...
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2answers
452 views

thyristor equation

I know how does an I-V curve of a thyristor look like, but is there any thyristor equation that can represent the curve?
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1answer
959 views

v-i characteristics of reverse conducting thyristor

May I know how does a reverse conducting thyristor work and its v-i characteristic? I have been searching all over the internet and libraries but the information about RCT is very limited. To my ...