Synchronous generator transient and sub-transient short circuit current

[@nicomettematthieu5316]

I’ve never seen such a great explanation of SG transients. thanks a lot

[@CesarDelgado-oi4zq]

Quite amazing visual! Great job Georg. 👍

[@15Moe51]

00:58 R.I.P. Headphone Users

[@cynicalsuka2463]

extremely useful. glad i found this channel

[@timhowell6929]

Not seeing the point so what are sub transient, transient and synchronous reactances? It’s never actually defined. Not a well organized explanation.

[@high4702]

As I understand you’ve showed that the exitation current increases under short circuit. But what about the voltage drop during short circuit??? Or both apper together exitation current increases and output voltage drops??? So, why do we need a exitation system which increases the exitation voltage for example during big induction motor start?

[@georgschett801]

I am not sure if I understand your question right. This video is about synchronous machines only and yes, there is a voltage drop during a short circuit.

[@high4702]

@@georgschett801 You showed that exitation current increases. So why do we need AVR??? And do we face the same problem wen we have permanent magnets?

[@georgschett801]

​@@high4702 The current in the excitation coil is jumping at the instant of a short for keeping the magnetic field within the excitation coil constant as per induction law. This jump however decreases again with the transient time constant and so the excitation current returns to the level before the short. The excess current caused by the short bypasses the excitation source through a diode parallel to the excitation source as per my video. The AVR has nothing to do with the short circuit, it is regulating the steady state voltage of the Generator. In case of a hypothetical permanent magnet there would be no transient short circuit but only a subtransient, in case of the availability of a damping cage.

[@madhugb303]

Great video 😊