Stacking Supply Voltages

[Reloadron]

The nuclear welding, did you work for B&W? Did a lot of work for their R&D lab in my apprenticeship.

B&W Nuclear Operations Group Euclid, Ohio . Formerly we were a Navy Power division of TRW then became independent. B&W was a prime customer of our Navy Nuclear Propulsion stuff and finally bought us. They do big stuff down in Barberton, Ohio and while we did some big, we focused on what we made for years, since the Nautilus, and that was the CRDM (Control Rod Drive Mechanism), the only moving part in the reactor core. Great years, many great memories and worked with some truly wonderful people. We were employee owned when B&W bought us and they paid well plus maintained our salary pension plus the 401K so I was fortunate.

Ron

 

[ronsimpson]

1) The MOSFET on the 100V line is fine. I would have just turned on/off the supply.
2) The capacitors and switches are a little of a mystery. I think that will add power just after the spark starts.
3) The two diodes are what I was talking about "diode ORing". When you use two supplies and diode them together.
4) The 210V supply I do not want to use. I like the "boost up" inductor because it will make a voltage that will go up until there will be a arc.
5)The MOSFET on the right side; I don't know what it is doing. (Is the MOSFET in parallel or serial with the arc?) Parallel= To short out the arc. OR Series= The arc return current goes through the MOSFET. Either way I think it is to stop the arc.
6) (The MOSFET on 100V and the right side MOSFET )= too many parts.

 

[shortbus=]

My dad and his dad were both boiler welders at B&W Barberton! One of the jobs I used to do for B&W was make tube plugs for reactor heat exchangers. A small plug that was inserted in a leaking tube, then explosive welded in place. And made test samples from different tube heats when they were building a new reactor. Also worked on a robot submerged arc welding head. Plus much more, always demanding tolerances but interesting stuff. Lot of exotic alloy machining that many people never get to work with.

What part of Youngstown is your daughter in law from? I'm actually in Austintown.

 

[shortbus=]

1) The MOSFET on the 100V line is fine. I would have just turned on/off the supply.
2) The capacitors and switches are a little of a mystery. I think that will add power just after the spark starts.
3) The two diodes are what I was talking about "diode ORing". When you use two supplies and diode them together.
4) The 210V supply I do not want to use. I like the "boost up" inductor because it will make a voltage that will go up until there will be a arc.
5)The MOSFET on the right side; I don't know what it is doing. (Is the MOSFET in parallel or serial with the arc?) Parallel= To short out the arc. OR Series= The arc return current goes through the MOSFET. Either way I think it is to stop the arc.
6) (The MOSFET on 100V and the right side MOSFET )= too many parts.

Thanks Ron.
1. The FET on the 100V supply is to shut the supply off after caps are charged. The caps are what will give the current in the spark on time. It is on to charge caps when the FET on the right(to ground) is off. This is done to make all of the sparks the same value, for better finish on the part. One company calls this "iso-spark" in their machines, but all of the pulse machines in the generation of EDM machines I'm replicating do it this way. The reason for doing it this way is the filter cap on the main power is large and has a high inrush current.

2. The caps and switches are for the energy of the spark, see #1.

3. Figured that's what you meant.

4. The boost inductor is the way I was originally leaning but like this better. It will give a known voltage to start the spark. By using the comparator and the and gate, it will cut out when the start voltage actually bridges the gap. And if the spark should go out during the on time, the start voltage should kick back in automatically. OR at least that's my theory for doing it this way.

5. The right side FET to ground controls the on/off time. When it turns on the one from the 210V will too. This will give the start voltage a path to ground and Voltage to that comparator. When the inverting comparator switches on this will shut off the 210V and allow the 100V from the caps to continue the spark. Then the ground FET shuts off and the 100V FET turns on and charges the caps again. Repeat until the cut/burn is done, this is set with a microswitch on the ram.
Again that's my theory. There must be an off time for the melted metal particles to be flushed from the spark gap or due to the small gap it will short out.

6. This is the only way I have figured out how to do all the things that are needed for a pulse EDM. Some of the plans for doing this at home have more parts and still don't work well.

 

[shortbus=]

After thinking on my simple schematic, my idea of the comparator and and gate won't work as I drew it. The needs to be a latch or flip-flop to keep the 210V mosfet turned off. If not the 210V and 100V will just oscillate back and forth. Back to the drawing board.