Heat cutting wire power source

  • Thread starter Pierre Desrochers
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Pierre Desrochers

Hi all. We have an application where we are cutting some plastic sheet (0.0025") wire a heated wire. We have the intention to supply our clients with systems having a 440 Vac supply (we are using 203/120 4 wires systems). The problem we have it's that we will need to add a 1500 VA x-former to our PLC panel in order to supply 120 Vac to our cutting wire DC card. We are using KBIC120 DC motor speed control card to supply the power to this wire. It needs 9 Amps and we kind a wish to get away without this "big" x-former. Those KBIC won't come with 440 supply... Do any of you have a hint for us on how to do this? We need the adjustable feature of the KBIC because the heated wire has to be adjusted for ambiant temp, air flow, etc, to make a good cut. The output is usually around 17 to 27 VDC and this low voltage is safer for humans... Any help will be greatly appreciated. Thancks! Pierre Desrochers Integral Instrumentation Inc. Montreal-Canada

Stephen Syputa

One option is to use another manufacturer's DC drive, such as the MINARIK 23001C, which is 120/240 selectable. (A heatsink is needed when this drive is used above 5 amps.) You could then get by with a smaller transformer. I have found this drive to be extremely reliable. There is even a version with an optically isolated control voltage input. If the customer's 3 phase supply has a neutral, then there is the possibility of using 277 volts as a power source. A 240Vac drive >might< work here with no modification. Stephen Syputa [email protected]

Alan Rimmington

It sounds to me as if you are going about this wire heating control the wrong way, it would be far safer to use a transformer with its secondary voltage nearer to the maximum voltage needed to heat the wire, say 30v. Then using a thyristor and a rectifier to control the heat in the wire. I would need to know how the temperature is controlled now – eg a 0-10v control signal 4-20mA loop etc as I am not familiar with the controller you are using. It would also be helpful to now the resistance properties of the wire. [email protected]

Michael Griffin

I don't know what your machine looks like, but a 1500 VA transformer isn't really all that big (or expensive). I should think you could use an external mount enclosed control transformer (e.g. from Hammond or Marcus) and mount it on the side or top of your control panel. When you want to go from a higher voltage to a lower voltage, there aren't too many common alternatives to a transformer. ********************** Michael Griffin London, Ont. Canada [email protected] **********************

Pierre Desrochers

The KBIC motor control is VERY usefull to us because it can sustain short-cct output, it is easaly adjustable with its speed control potentiometer, it's very small ( 4"x2") and very cheap (about 100$CAN). We adjust the heat of the wire to make a fast cut of a 0.0025" plastic wrapping film. We are cutting "on-the-fly" whyle the material is being layd onto a product. We adjust the heat needed to make this cut in relation to how fast our mechanical arm making the movement needs to go an how the ambiance interacs with it. If in winter or in a windy environement the operators raise the heat a little... Its basicaly ON/OFF We will be supplying our end-users with a fully 440Vac panel but would like to have just a little 500VA x-former inside the panel for controls and PLC. If we need to put a 1500 VA inside, we will have to use a bigger panel (heat dissipation, etc) OR we will have to fit the x-former to the side of the panel... it will work but have an ugly look. I like Alan Rimmington's idea about a 440/30 Vac x-former but how would it sustain a short-circuit... Today our system don't care about it... it's a DC motor power generator and it has a serial resistance already in the cct so it does not fail when someone screws up and installs a normal piece of wire instead of the heating element type of wire we use to make the cut. Pierre Desrochers Integral Instrumentation Inc. Montreal - Canada