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Registered Member #3395
Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193
Hi there guys,
I was arcing with my ZVS driver and noticed that there was a lot of corona hissing noises and a small sparking noises going on. I looked on the underside of the two flybacks I tested separately and the pins started sparking to the core. Then, one time I turned it off, I got a nasty little zap from the wires on the switch.
Obviously, the whole circuit and batteries are 'floating' at an extremely dangerous voltage and is ungrounded. That's probably why the pins were arcing to the core so that the voltage could try and find a way to ground(via me unfortunately). I do not feel safe operating the ZVS until I can get some advice on this. Obviously, it needs to be grounded somehow. Jan Martis (Dr. Kilovolt) grounded his flyback cold and core to mains earth. However, the ZVS does not run off mains so how I can ground the circuit so that it is not 'floating' at a dangerous potential voltage?
Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
It's obvious that the device produces a difference of potential between the regular HV terminal and what should be ground. If the "ground" is floating, the potential there is limited by capacitance and leakage to the true ground. This is one of the main reasons of disastrous failure of these circuits. A wire to the power line ground, or to a big metal object serving as "counterpoise", are simple solutions.
Registered Member #3395
Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193
So my options are to connect the ground pin to the ground in the mains socket? Could you describe the "counterpoise" a bit more to me? Is it just a big object connected to the ground pin that adds capacitance?
If I use either of these methods, will it stop the sparking to core and shocks from the switch?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
If you connect each set of pins (ie. pins that are internally connected together through windings) at one point to the core, this will stop sparking to the core but not the shocks from the switch. To stop this you need to ground the driver to something that is connected to earth, such as the water tap or central heating pipe if you don't want to use mains earth. Or use a long insulated handle on the switch...
Registered Member #3395
Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193
Dr. Kilovolt wrote ...
If you connect each set of pins (ie. pins that are internally connected together through windings) at one point to the core, this will stop sparking to the core but not the shocks from the switch.
Right thanks a lot. I could ground the flyback cold because I just noticed a copper pipe going through the side of the garage in a grill in the concrete wall that may go into the ground. So if I connect all of the pins together (except the flyback ground output) and connect it to the core? One time the core started sparking to the primary but didn't kill the circuit... If I connect all the pins (except HV ground) to the core, won't this increase the risk of it shocking me via the swirch unless the core AND flyback cold is grounded too?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
You cannot connect all the pins together as this will short out the internal coils. You must find a set of pins which are internally connected together, and ground just *one* pin from each set of interconnected pins.
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
Józef C wrote ...
Hi there guys,
I was arcing with my ZVS driver and noticed that there was a lot of corona hissing noises and a small sparking noises going on. I looked on the underside of the two flybacks I tested separately and the pins started sparking to the core. Then, one time I turned it off, I got a nasty little zap from the wires on the switch.
Obviously, the whole circuit and batteries are 'floating' at an extremely dangerous voltage and is ungrounded. That's probably why the pins were arcing to the core so that the voltage could try and find a way to ground(via me unfortunately). I do not feel safe operating the ZVS until I can get some advice on this. Obviously, it needs to be grounded somehow. Jan Martis (Dr. Kilovolt) grounded his flyback cold and core to mains earth. However, the ZVS does not run off mains so how I can ground the circuit so that it is not 'floating' at a dangerous potential voltage?
Cheers, Jozef
I could be wrong, but based on your description, it sounds like you do not have the "low" terminal of the hv secondary grounded. In that configuration, the low terminal will arc to whatever it can find, as an attempt to ground itself. I think that it's a simple matter of making sure that your hv secondary "low" terminal is grounded to both the core of the transformer, and also the common or ground rail of the circuit (typically one terminal of your battery). You should NOT need to run wires to water pipes or anything crazy like that!
Registered Member #3395
Joined: Thu Nov 04 2010, 08:42AM
Location: Christchurch, New Zealand
Posts: 193
I understand what you are trying to say. . That sounds perfectly logical to me. I can try however I will be annoyed if the ZVS goes pop. This may sound kinda stupid but what is HV low going to do to the battery?
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
Józef C wrote ...
I understand what you are trying to say. . That sounds perfectly logical to me. I can try however I will be annoyed if the ZVS goes pop. This may sound kinda stupid but what is HV low going to do to the battery?
In most electronic circuits, there is a common point that everything goes to, and is often refered to as "ground". In battery operated curcuits, especially where there is a low voltage portion of the circuit, and a separate high voltage portion, the two portionss are sometimes electrically isolated from each other. The practice of isolating the HV from the LV may be done for two reasons. One is so that HV noise doesn't get into the LV circuits, which can cause instability or complete shutdown. The other reason my be for safety. By isolating the HV circuits, you reduce the likelihood of the user getting shocked from stray voltage that may have gotten to switches, pots, and other poertions of the circuit where it ain't supposed to be!
If you are using a basic ZVS flyback driver, then it's probably Okay to run the grounds together from the HV and the LV circuits. The only place that you should see or measure HV is in the "hot" parts of the HV circuitry (e.g., the hot flyback secondary lead, the CW multiplier, and the HV output termination). If things are properly grounded (to the common PS connection) then you should not have any corrona or arcing on any parts of the circuit that are referenced to ground.
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Dangerous ZVS Driver 'floating' at 30kV+ ungrounded - Safety advice please!
