Thyristor in AC UPS

[zacharialamsyah]

Dear all

In my facility, there are AC UPS equipped with thrystor inside, and I'm googling , i found the thrystor means is function as a transformer or the AC UPS design is transformerless , is that correct. Can anybody explain what the " thyristor " is?

Thank you for comment and opininion
regards
zachari alamsyah

 

[Skogsgurra]

The thyristor is a semiconductor "diode" with an extra electrode, the GATE.

It does not conduct current at all if not "triggered" ON with a short current pulse in the Gate. When it has been triggered ON it remains so until current goes to zero, which it does periodically in an AC application.

Since the Thyristor, when ON, acts like a diode, it cannot conduct current from Cathode to Anode - only from Anode to Cathode. That means that you need two Thyristors for AC, one for the positive half-wave and one for the negative half-wave. For a Three-phase system, that means that you need six Thyristors.

The name stems from Greek "Thyra", which means "Door" and the generic "-istor" (same as in resistor, transistor etcetera).

Forget about the transformer thing. It seems to be an attempt to explain the device in a "simple" way. And those simplifications more often cause confusion than they bring clarity.

BTW - googling should have told you what a thyristor is. Didn't it work?


Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[zeusfaber]

In horribly simplistic terms, a thyristor is a semiconductor device that acts a bit like an electronically controlled push-button switch. There are several different types - which differ mostly in how easy they are to turn off once you've got them going.

They can be made to turn on and off very quickly. In UPSs, they are often used to chop up the dc output from a battery to create something that looks like the ac waveform that the consumer wants. This might be fed into a transformer, or go direct to the consumer, depending on the design of the UPS.

A.