Does a Voltage Divider board Require Power

[ChrisO]

Does a Voltage Divider Board require power? I am working on upgrading a plasma table to add THC. We have a Thermal Dynamics Pak Master Model: PAKMSTR100XL. I’d like to install Robot3T THC Voltage Divider Board inside the plasma cutter. I see the Divider Board has DB-9 connector that has 24VDC connections also has other functions (Out-Fire+, Out fire -) which I think is the same as the Pak Masters Ark-OK signal, ( which I have). If I intend to only use the (Tip+ and Tip-) do I need 24VDC power to the Voltage Divider Board? Attached is Voltage Divider Board Reference info.

[acourtjester]

Here is a web site with the manual for you THC and it shows an external 24 volt supply on page 4

[djreiswig]

It looks to me like the divider portion of that unit is just used internally for the thc itself. You can either feed it raw arc volts or 50:1. I don't see a place to get the divided volts out of it. I think it just uses the divider as part of the thc.
I don't think a stand alone divider would need power as essentially it's just some resistors that divide the voltage at a desired ratio. It doesn't appear that this unit can be used like that.

[ChrisO]

Thanks for your reply. The Vital systems ArcPro Plasma system requires 0-10 volts input from the Voltage Divider Board. Does anyone have a recommendation for another Voltage Divider Board?

[djreiswig]

You could always build one. Just need some resistors with a high enough voltage rating. Search the forum, I'm sure there is some info on them here somewhere.

[TJS]

Can you just use a laptop AC to DC power brick with the correct voltage parameters. Find the positive (it is usually the center of the plug in jack) and find the negative. Strip the wires and hook it up and no building.

[ChrisO]

To djreiswig, Nice idea but I'd prefer to purchase one, as I have my hands full retrofitting a plasma table's controls.
To TJS, Also a nice Idea but was hoping to determine if it was even needed. I'll just have to add power, if I can't find a different board. I'll keep researching

[djreiswig]

What ratio are you looking for?

[robertspark]

what range are you looking for to 0-10v,

0-250v, 0-350v?

I can make a divider card for you (I have done it before as a plugin kit for an older hypertherm).

they are neither difficult nor complex to make

[ChrisO]

With regard to what range, it needs 0-10 volts. but the ratio values I need help with.
From the Plasma Cutter Name Plate: "Secondary rated 70 amps @ 125 volts, Open Circuit voltage (OCV) 325 volts 40% duty cycle." Attached picture is from the cutters manual and is the only place I found references to output voltages.

And from the Controllers ArcPro Plasma Card, the following is required: "Setup 77ISO - ….. This adapter accepts 0 to 10volts from the Plasma unit. You must select the proper divider to reduce the tip voltage (usually in the range of 300V) down to the 0-10 volts range."

To robertspark: Thank you for the offer, I'll keep that in mind as I educate myself through this process. When you made the divider card in the past, did you have to provide a power source or does the 0-10 volt power come through the divider card from the plasma cutters tip?
Thank you all for your interest in this project!

[robertspark]

no power supply, just resistors.

you can add inductors too to offer a degree of protection against HF (high frequency) and signal filtering.

0-300v >>> 0-10v is a 30:1 voltage divider

the resistance ratio is 31:1 though.....

looking at your plasma cutter manual, the voltage output is a raw output .... BUT. the manual says that the outputs are protected by 100k resistors.....

if it were me, I would get a 10k resistor and 2x56k resistors....

I would install each of the 56k resistors to the end of the raw outputs and bridge them with a 10k resistor.

the two connections of the 10k resistor then provide you with a like over 30:1 output which you can feed into your thc input....

[ChrisO]

Thank you robertspark for your insight. I will begin the search for a board that offers 30:1 ratio. If any one knows of one please advise, otherwise I may have to resort to having one made.