AW: Re: Aw: Re: Re: AW: [EVGRAY] Re: All information about Diode Plug.

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: "[email protected] [EVGRAY]" <[email protected]> 
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 18:07 Uhr
Von: "s.friedrich@... [EVGRAY]" <[email protected]>
An: [email protected]
Betreff: Re: Aw: Re: AW: [EVGRAY] Re: All information about Diode Plug.
 
Hi Ole, I have rebuilt the thyristor or I have to install an additional diode because I have used the built-in module diode which is not separable from the thyristor.

The curves are the same now, really great. But somehow I have the feeling that it is right and wrong. The diode plug purrs like a kitten now. Laugh The hard hammering into the transformer is gone. I always thought to saturate the transformer you have to deliver a strong short pulse. I do not get the high voltages anymore either, at 200 volts RMs is over.

I completed the circuit and took some pictures, probably only mailable.

regards

Sven

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

(Message over 64 KB, truncated)

Hi Sven,

Yahoo seems to be quite unstable at the moment. No attachment and no pasted image neither! Here's the message. The image is pasted below as the message may be truncated after pasting. 
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], <onielsen@...> wrote :

 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.

Empty body

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  ...