Hypertherm soft start option
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  1. #1
    Join Date
    Feb 2007
    Aberdeen, UK
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    Default Hypertherm soft start option

    Anyone have experience with these?

    We have a HPR400XD. When we installed it we did a bunch of power tests and decided to run it off of a (hired) generator because of the extreme inrush current when it starts, and we were worried about causing brownouts in our machine shop, which is connected to the same transformer. It ultimately got vetoed by the power company because they didn't think our transformer would be able to completely buffer that much inrush and might cause voltage drops upstream.

    Marginal profits on that side of the business are driving a push to get rid of the generator.

    Do the soft start upgrades make a significant difference?

  2. #2
    Join Date
    Jul 2007
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    If it's the "Inrush Installation Kit" and the inrush currents is at power on, not at arc strike, then it will almost certainly do the job.

    Not in the same league as you at all, But I've just had to make/install an inrush control circuit on my little 200A multi-process box because it had a habit of welding its switch contacts closed on power-up...

    They don't seem to quote the resistor values on the 428064 kit, but they should be able to tell you what the peak inrush current will be after installing the kit with the voltage you've got (415?). If it's still too large for your substation transformer, it will be possible to use higher value resistors to limit the inrush current to what your electrical engineer or the distribution company tell you is safe. You'd probably have to get those manufactured, but Hypertherm might be willing to cooperate it it was needed?

    Edit to add:- On my little box, I could understand why the manufacturer didn't bother with a soft-start (Cheap!), But your machine is of such a rating that I would have thought a soft start should have been part of the design. If not for the utility/factory's sake then just to ease the life of its own power supply components.

  3. #3
    Join Date
    Feb 2013
    Northern califorina, usa
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    The Hypertherm Soft start inrush kit will help to some degree.
    The kit will decrease the effects of inrush current that occurs when the main contactor closes.
    Question, do you need the HPR 400 for the size/type and cut quality of material you are cutting?
    Or could you drop down to a smaller high def machine or for that matter a standard air or gas mix standard plasma?
    Just the cost of a rental Generator has got to be kind of on the costly side over time.

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