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Hi Sven,
Just lost my answer. I'll try again.
"The small diodes are protective diodes to protect the small thyristor as the gates of the power thyristors are very low ohmic in both directions. "
Use resistors instead as diodes have very low impedance when they starts conducting. A slight change in voltage gives a big change in current as they are very nonlinear devices.
"I think to remove the dashed line and connect the ignition in front of the transformer coil but on the right is that also so and why is that a monitoring?"
Exactly! The left hand side triggering circuit has one voltage drop more than the circuit on the right hand. It sees the voltage across the primary coil to the left. The right hand side triggering circuit doesn't see the voltage across the primary winding to the right. Thus the left hand side depends on what happens across the primary winding which the right hand side doesn't do.
Monitoring the voltage (U_left or U_right) across each capacitor for triggering the SCRs is what is being done. At least it's being done at the right hand side while at the left hand side the voltage across the capacitor plus the voltage across the primary is being monitored. The rest of the voltage drops (blue arrows) are constants determining the triggering voltage.
"And why did you mark the Variacs and the protective diodes at the gate of the power thyristors?"
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.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hi Ole, I do not really understand that. I think to remove the dashed line and connect the ignition in front of the transformer coil but on the right is that also so and why is that a monitoring? And why did you mark the Variacs and the protective diodes at the gate of the power thyristors? Greetings Sven
Von Samsung Mobile gesendet
-------- Ursprüngliche Nachricht --------
Von: "onielsen@... [EVGRAY]"
Datum:08.02.2018 00:18 (GMT+01:00)
An: [email protected]
Betreff: Re: Aw: Re: Re: AW: [EVGRAY] Re: All information about Diode Plug.
Hi Sven,
The left hand side triggering circuit doesn't monitor the voltage across the capacitor like it is done on the right hand side. See suggested correction:
Are the small diodes for increasing the gate trigger voltage by an extra 0.7V?
The variac inductors limit the charging current to the capacitors. The top diodes in series with the variacs don't seem to be necessary like the small diodes in series with the gates of the power SCRs. Current entering the variacs are prevented from reversing by the two bottom diodes of each half part. The top diodes only dissipates extra power and adds cost to the circuit.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Sorry, the drawing was wrong what the triggering of the positive diode plug betraff, it works great. Of course, a few series resistors for tripping must be adapted to the auxiliary thyristors. There are some with high sensitive gate that can be ignited with μA then you have to work very high impedance.
regards
Sven Gesendet: Mittwoch, 07. Februar 2018 um
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