Low cost motor drive experience?

[Josh Jones]

First off, greetings! I was last here somewhere in 2011 or so, and have been working on radio and TV stations around the country to pay the bills. I'm digging through my old film stuff and getting a temporary room set up to see what condition the film collection is in. All my machines are approaching 80 years old, and the parts stash is slowly evaporating. That said, I think it would be a good idea to add an inverter drive motor to the setup to more precisely control the ramp up of the machines. The first system I want to convert is a SH-1000 driving a BX-100. The other two machines are BX-80's atop 9050's which I will also convert if this goes well. I've seen low cost inverters all over the place for under $100 in some cases. I assume these are just Chinese clones of western drives, but has anyone on here had any experience using them?

Josh

[Steve Guttag]

You might find something that works. However, what I've found is that you really need to mate the motor and VFD well. The VFD needs to have the HP to get the projector running as well as the ability to increase its torque on start up. You want the motor to evenly ramp up/down and not seem to surge up with a succession of lurches. I'd think the cheaper VFDs lack the granularity to set how the torque curve works (and change its oscillation frequency to not have it be so noisy at projection speed).