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Questions tagged [thyristor]

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10
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4answers
2k 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
votes
1answer
28 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
votes
2answers
59 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 ...
0
votes
0answers
73 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
vote
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
vote
3answers
72 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
74 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
votes
1answer
185 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
votes
1answer
199 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
40 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
votes
2answers
56 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
votes
1answer
130 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
vote
2answers
141 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
votes
0answers
39 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
votes
0answers
31 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
144 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
votes
1answer
80 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
vote
2answers
113 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
votes
2answers
136 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
votes
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
votes
1answer
72 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
votes
0answers
64 views

I have this error in my pspice thyristor model.(missing node)

I am trying to model thyristor but I have error that showing missing node .SUBCKT SCR 1 3 2 * model anode +control cathode * name voltage S1 1 5 6 ...
0
votes
1answer
1k 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
313 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
votes
1answer
102 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
votes
2answers
432 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
votes
1answer
122 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
votes
0answers
426 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
votes
2answers
181 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
votes
1answer
91 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
votes
1answer
63 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
votes
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
118 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
52 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}\$ ...
0
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0answers
45 views

Circuit with an ideal thyristor analysis

I've the following circuit, and I want to know if my derivation is correct. (Btw the thyristor is assumed to be an ideal component): For the input voltage we can write: $$\text{U}_\text{in}\left(t\...
1
vote
2answers
246 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
241 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
votes
2answers
197 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
votes
1answer
484 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
votes
3answers
335 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 ...
1
vote
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'...
1
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2answers
400 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?
-1
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1answer
902 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 ...
0
votes
1answer
824 views

Is it possible to replace a DIAC circuit with an SCR circuit to drive a TRIAC

I have a triac DIAC cirtcuit. I don't have any DIACs on hand, but I do have plenty of TN1215s. Is it possible to generate the required pulses using an SCR to drive the TRIAC's gate?
1
vote
2answers
93 views

What is a 'current filament' in a Gate Turn-Off Thyristor?

I’m reading a GTO document and I’m not able to understand this part: "The anode current is crowded into higher and higher density filaments in most remote areas from the gate contact. This is the ...
0
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1answer
5k views

UJT firing circuits for SCR

Is it possible to replicate a random pattern of trigger and charge times to an UJT firing circuit for an SCR configuration? What I mean is that, UJTs usually have a periodic sequence to them. ...
0
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0answers
780 views

3 phase fully controlled rectifier

A 3 phase fully controlled bridge converter is fed through star-delta transformer. The converter is operated at a firing angle of 30 degrees. Assuming the load to be a RL load and load current to be ...
1
vote
1answer
341 views

Thyristor gate voltage at on state

I'm Vuong Kha Sieu and i'm 14 years old. I have a great interest in electronics and I wish to seek your help about this question. Please forgive any grammar mistake I made, since I'm not a native ...
0
votes
1answer
184 views

Read Thyristor(Triac) specification

I have this Triac which I believe is failed because of a hight current we had in the house. The varistors that were next to it were totally burned. I am trying to buy some online, but I really don't ...