All scope measurements must be referenced from ground. With these high voltages you should be using a 10x probe. Are you doing otherwise?

Good question. I don't really know. I lost the packaging that came with it a long time ago. However, I did have to set up the oscilloscope with a 10X attenuation in order to represent the voltage. Does that help?

 

Good question. I don't really know. I lost the packaging that came with it a long time ago. However, I did have to set up the oscilloscope with a 10X attenuation in order to represent the voltage. Does that help?

Your probe should say 10x right on the probe body. Is this a PC based or real scope? What's the bandwidth?

Take a look at this attachment. Did you do this? Doing so will short that node to ground. I know people that have actually cut off the ground pin on their scope's power cord to be able to do what you see in this schematic. Don't ever do it! Ever!! It's deadly dangerous because it puts the scope's case, BNC connectors, etc at 200V above earth and this circuit's ground.

EDIT: Connecting the scope's ground lead to anything other than circuit ground isn't acceptable; even with a battery operated scope or laptop PC based scope that's not connected to the mains.

 

Well i live in sweden so even if OSHA and others did get air about it, they cannot do anything as im not a US citizen

I don't think that they want to do anything about it other than offer you remuneration for copyright.

I hope Swedes have a good sense of humor because I can't help myself.

 

Your probe should say 10x right on the probe body. Is this a PC based or real scope? What's the bandwidth?

Take a look at this attachment. Did you do this? Doing so will short that node to ground. I know people that have actually cut off the ground pin on their scope's power cord to be able to do what you see in this schematic. Don't ever do it! Ever!! It's deadly dangerous because it puts the scope's case, BNC connectors, etc at 200V above earth and this circuit's ground.

EDIT: Connecting the scope's ground lead to anything other than circuit ground isn't acceptable; even with a battery operated scope or laptop PC based scope that's not connected to the mains.

Here's the thing. My oscilloscope's return pin IS earth ground. While I'm not doing what your schematic states, the oscilloscope itself was design that way. Heck, I retried what I did with earth ground and I ended up blowing my 15A fuse.

 

Here's the thing. My oscilloscope's return pin IS earth ground. While I'm not doing what your schematic states, the oscilloscope itself was design that way. Heck, I retried what I did with earth ground and I ended up blowing my 15A fuse.

It's supposed to be earth ground, so I don't understand what's happening there. The only logical conclusion is that the point you think is ground... isn't.

 

It's supposed to be earth ground, so I don't understand what's happening there. The only logical conclusion is that the point you think is ground... isn't.

Well, I am using the negative side of a bridge rectifier as a ground. Either way, I'm really afraid of scoping the thing.

But I have some develop news. I manage to turn frequency down to 25kHz and I got some more beefy IGBT. However, the system is still blowing up at 60% Duty cycle. Its a pretty loud explosion too. The picture attached is what happened to my IGBT afterwards.

I also got my current clamp and measured that my bridge rectifier is drawing 1.5 A, which makes me think that one possible problem is that my resonant tank storing too much voltage/current.

 

Use your DMM to measure the potential between your scope's ground and your circuit's ground. Make both DC and AC measurements. The DC and AC potential should be near zero.

 

OK, I talked to a peer of mine and I think I manage to figure out why my scope keeps blowing up. According to my peer, my circuit doesn't have a transformer between my bridge rectifier that is outputting 160VDC and my wall outlet, which makes him to believe that its shorting to line-neutral.

Either way, scoping and my FETs exploding are an entirely different matter all together. What I'm going to attempt are to do with my circuit is to

• adding a 100k resistor between my 160VDC and my inverter and test the circuit out that way
• if the previous doesn't work, then I'm going to add a voltage divider before the inverter and see if I can step down the voltage, but still get it close to 160 VDC. What I'm hoping this will do is get my inverter to be high voltage but low current and hopefully it will transfer to the workpiece in a low voltage, high current setting.
  

 

<snip> my circuit doesn't have a transformer between my bridge rectifier that is outputting 160VDC and my wall outlet, <snip>

WHAT?!?!

If I could make the EEK smiley bigger I would. Are you trying to kill yourself?

 

By the way, there's a good chance that your bridge was destroyed the first time you hooked your scope ground to your circuit ground. The mains neutral and ground are bonded together in your service panel!

 

That I figured as much. I got rid of that rectifier after my last incident when my caps exploded months ago. Besides, the only reason I'm not using a transformer is that I'm perfectly happy with a 160VDC from my rectifier and I already have a 5A fuse for protection not to mention the system isn't going to draw more then 15 A or else it trips the breaker.

 

That I figured as much. I got rid of that rectifier after my last incident when my caps exploded months ago. Besides, the only reason I'm not using a transformer is that I'm perfectly happy with a 160VDC from my rectifier and I already have a 5A fuse for protection not to mention the system isn't going to draw more then 15 A or else it trips the breaker.

Do you remember when I posted this?

It's supposed to be earth ground, so I don't understand what's happening there. The only logical conclusion is that the point you think is ground... isn't.

Well, as it turns out that's exactly what's going on here. This begs the question... How can you prototype and troubleshoot a circuit that requires a scope as its primary diagnostic instrument? Your circuit ground is not ground but a circuit common. This point is dangerously above ground.

 

Hello,

The thread has turned into a circuit that violates the ToS.

I am closing this thread as it violates AAC policy and/or safety issues.

Quote:
6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

• Any kind of over-unity devices and systems
• Automotive modifications
• Devices designed to electrocute or shock another person
• LEDs to mains
• Phone jammers
• Rail guns and high-energy projectile devices
• Transformer-less power supplies

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