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Does anyone know how Glassman "reversible polarity" HV power supplies work?

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jpsmith123

Sun Jan 30 2011, 09:50PM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
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Posts: 843

I'm assuming that a floating HV secondary winding drives dual half-wave, opposite polarity VM stacks; and to change the output polarity, two connections would have to be swapped. Is that how they do it?

Proud Mary

Sun Jan 30 2011, 10:32PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

You have assumed - almost - right!

Here is the Spellman 1999 patent:

United States Patent 6002600
Reversible polarity high voltage power supply
Assignee: Spellman High Voltage Co. (Hauppauge, NY)

Patrick

Mon Jan 31 2011, 01:21AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Wow, an insulated electric-motor gear train, to rotate the whole potted VM.

jpsmith123

Mon Jan 31 2011, 02:00AM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
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Posts: 843

I didn't think to look for a patent. Thanks for the link.

In taking a quick look at it though, it seems to me that some of the schematic diagrams are wrong. For example I don't see how the arrangement shown in Figs. 1B and 2 can work.

I thought I would see something like this:

Patrick

Mon Jan 31 2011, 05:05AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Yes I do what you have drawn, reverse the direction of the diodes. but they show a mid point tap with no reversal of diodes. I wonder whether they ignore the lower half due to polarity? and that ground on the other side takes care of the rest.

Wolfram

Mon Jan 31 2011, 06:59AM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Patrick wrote ...

Yes I do what you have drawn, reverse the direction of the diodes. but they show a mid point tap with no reversal of diodes. I wonder whether they ignore the lower half due to polarity? and that ground on the other side takes care of the rest.

Both the lower half and the upper half contribute to the output voltage. Multipliers don't need the AC feed to enter at the bottom of the stack, I think feeding it from the middle of the stack results in an overall lower output impedance of the multiplier (but don't quote me on this), but the main disadvantage is that the coupling capacitor needs to stand off much more voltage than the rest of the caps, the full DC voltage at this stage in the multiplier plus the AC voltage.

Ash Small

Mon Jan 31 2011, 07:07AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

From the Glassman EW series instruction manual:

Also from the Glassman EW series manual:

1296458175 3414 FT107463 Polarity Reversal 3

[Edit: Double post...]

Proud Mary

Mon Jan 31 2011, 08:53AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

jpsmith123 wrote ...

I thought I would see something like this:

That is what is more or less being illustrated in Fig 1C - the "prior art" claimed to have been improved upon by this patent.

One should remember that the existence of the patent doesn't mean necessarily that Spellman have ever produced and sold the rotating C&W PSU.

Worth a look for its inventive electromechanical engineering is:

MODULAR CASCADED REVERSIBLE POLARITY ULTRAHIGH DC VOLTAGE SUPPLY SYSTEM
United States Patent 3643105

jpsmith123

Mon Jan 31 2011, 01:15PM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843

But Fig. 1C shows two separate, individually selectable transformer/multiplier units (btw note the error/omissions in this figure; i.e., both multipliers are shown having the same orientation of diode polarity, and no grounded terminals are shown). Whereas in the schematic I posted, the HV output is floating thus the polarity would be reversed by simply swapping the connections to the output terminals of the two multiplier stacks.

Proud Mary wrote ...

jpsmith123 wrote ...

I thought I would see something like this:

Proud Mary

Mon Jan 31 2011, 01:23PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Yes, there does seem to have been a drafting error in the patent 'prior art' diagram.

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