Body
Hi Sven,
If the gate was too sensitive an extra resistor could be placed between the gate and the cathode to form a voltage divider with the gate current limiting resistor.
The reason for the extra diode at the variable inductor could be some leftover from an earlier design from before adding the inductor or choke. At least it can be omitted with the two other diodes in place as the current will never go in the reverse direction. Without the inductor (choke) only one diode is needed. The bottom diode is for charging the capacitor and the one sharing its anode (or cathode) is for 'discharging' or demagnetizing the inductor. I.e. the flyback voltage from disrupting the current through the inductor makes the current 'discharge' to the capacitor which is then being charged.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hi Ole, I'm afraid that over the Powerthyristor cathode on the gate a reverse voltage destroyed the auxiliary thyristor. before I installed the diodes, the thyristors broke, but at the same time we installed the series resistor on the anode side of the auxiliary thyristor, maybe it is the reason that everything runs stable. Somehow you're right, but why did Hector draw the diodes between Variac and capacitor? Greetings Sven
Von Samsung Mobile gesendet
-------- Ursprüngliche Nachricht --------
Von: "onielsen@... [EVGRAY]"
Datum:09.02.2018 00:10 (GMT+01:00)
An: [email protected]
Betreff: Re: Aw: Re: AW: Re: Re: Re: AW: [EVGRAY] Re: All information about Diode Plug.
Hi Sven,
"There are many auxiliary thyristors gone without the diode a series resistor for current limiting I have installed for the auxiliary thyristor as in the drawing. The ignition of the power thyristors has worked very well so far, my idea is more likely to high sensitive thyristors that can be switched with μA thereby would be wasted little energy for the ignition and perhaps rather the synchrony of the system can be achieved."
Diodes don't limit the current very much as they're good conductors in the forward conduction direction. They have a forward conduction voltage drop of around 0.7V or a little more when at heavy load.
"The diode between reactor (Variac) and discharge capacitor should prevent a resonance that can arise between the reactive components"
The other two diodes at the other end of the variac already prevent the current from going in the opposite direction of the first diode at the top end. The top end diode is in series with the double split diodes and the current form either one of the split diodes also goes through the top end diode. Thus the top diode is only introducing another voltage drop (power dissipation) for current going through the variac. This is the brother in law effect (if one's brother in law sells diodes).
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hi Ole, first of all many thanks for your help, I will consider the change with positive diode plugs the ignition energy is removed after the transformer coil and the left diode directly from the capacitor. The charge curve and discharge curve of the two capacitors are almost identical now perfect, now you can work on the vote.
"The small diodes are protecting the small thyristor as the gates of the thyristor are very low ohmic in both directions."
Use resistors instead of diodes when they start conducting. A slight change in voltage gives a big change in current as they are very nonlinear devices "
There are many auxiliary thyristors gone without the diode a series resistor for current limiting I have installed for the auxiliary thyristor as in the drawing. The ignition of the power thyristors has worked very well so far, my idea is more likely to high sensitive thyristors that can be switched with μA thereby would be wasted little energy for the ignition and perhaps rather the synchrony of the system can be achieved.
I think that is still a long way, but a very interesting experiment.
"And why did you mark the Variacs and the protective diodes at the gate of the thyristor power?"
The variacs have the two bottom diodes prevent any current from changing direction. Thus the top diodes at each variac can be omitted as the current through the variacs never changes direction. The voltage across them will change depending on receiving energy or supplying energy."
The diode between reactor (Variac) and discharge capacitor should prevent a resonance that can arise between the reactive components. I will send you the original circuits.
regards
Sven ...