They have to have some type of microprocessor, non-volatile storage, more than
one switch/button, sometimes a rotary knob, some type of display too, even if
it's just a pair of 7-segment LEDs. But they do all of that and sell it for
LESS than the 'dumb' devices that are fixed function with nothing adjustable.
On Wednesday, January 3, 2018, 2:42:37 AM MST, Les Newell
<[email protected]> wrote:
Hi Gregg,
The complicated and expensive bit is in creating the 3-phase. Most of
the other functions are simply software tweaks that in mass production
add next to nothing to the cost of the drive.
Les
On 02/01/18 23:35, Gregg Eshelman via Emc-users wrote:
> I run the VFD (that's never varied) on my old Monarch lathe without using
> braking. It has terminals to connect a braking resistor but for this machine
> there's no need.
>
> What I find crazy is that a simple, single function device that only converts
> single phase to three phase, without all the fancy features of a VFD, costs
> so much more than a VFD. When a 3HP VFD for 220~240VAC input can be had for
> under $300, why isn't a version that does absolutely nothing, no adjustments,
> no variation, no programmability, but do the phase conversion not cost well
> under $200 instead of a whole lot more?
> If some company produced a box that was just a phase converter with an on/off
> button and terminals for a remote switch as the only 'extras', and put a
> $199.99 price on it, they'd be hard pressed to keep up with demand.
>
> On Tuesday, January 2, 2018, 9:33:50 AM MST, Dave Cole
><[email protected]> wrote:
>
> So what exactly do they do when the bus voltage rises during decel ??
> Or is there no decel control at all?
> I've never seen a drive without braking circuitry and DC bus voltage
> control.
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