As part of my 2330 lv3 am required to know about thyristors.
I just want to confirm my understanding is correct. A thyristor is basically similar to a transistor, only it stays switched on when it's trigged for as long as there isn't a break in the circuit it's switching. Am I correct?
Electronic – what is a thyristor
scrtheorythyristor
Related Solutions
Nothing... Well unless it is really really high and you get GTO like behaviour ( although the magnitude and di/dt needed to force the abnormal affect is very unlikely)
Each straight line can be characterised by an equation based on 2 transistors.
- The breakover or trigger voltage is the same as any power transistor, Vbe and current gain for trigger current,
- the foldback negative resistance depends on gm in two transistors and resulting saturation voltages plus 1 diode drop and Rs or ESR.
- The follow-on positive resistance depends on the power rating and junction size - the Rs or ESR is proportional to Pd power rating of the device. e.g. Rs=k/Pd where k is approximately = 1
- ( the same applies to all diodes and LED's ) with a wide tolerance
- the reverse characteristics are likely similar to transistor PIV breakdown.
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Best Answer
Pretty much correct.
It's not while there is no break in the circuit, but while the thyristor is forward biased.
So, while there is a positive voltage potential across the Anode/Cathode terminals.
That means that if an AC signal is fed through it the thyristor will switch on when the gate is driven high (as long as the AC signal is currently in the positive phase), and stay on until the end of the current positive phase of the signal - when the potential drops to zero or below - thus creating a zero-crossing switch-off.