I’ve got a small R&D fuge that isn’t slowing down promptly enough for my liking, and I’d like to learn how to brake it
It’s direct from China, and came with a large resistor and a Mitsubishi D700 single phase 200V drive in the control box.
I’ve downloaded the fine manual (294pages), and am about ready for some light reading, but I’m gonna have questions and I’m sure there is someone here who can help…
Because I met them, and discussed this on the exhibit floor in vegas.
…every fuge comes with a free toaster oven…
Anyway, I’m off to learn more about programming VFD’s, and I’ll either be back with something to share, or looking for an assist on enabling my free toaster oven.
Lots of ways to break a motor, because of the inertia of the centerfuge id assume you’d need some form of dynamic breaking with a grid resistor (simpler than regenerative breaking) you could also plug break it by injecting the reverse current into the windings. Chances are your single phase drive won’t have a large enough internal resistor to break the motor very quickly.
it has a single large “external” (in the control box with the drive) resistor. don’t know what “large” means electrically yet. running the fuge at the moment.
gonna double check if it has the recommended thermal relay to break the brake circuit if things get to warm in there. don’t think it does, but that’s from memory, and I wasn’t looking…
fuge does slow faster when I hit the red “stop” button than when I hit the “reset” or dial the speed down to zero. IR thermometer detects no heat from resistor.
trying to wrap my head around the various flavors of braking resistor. this one is wire-wound ceramic, if it gets hot it should glow
How hot it gets depends on how fast the drive can shunt the current generated to the resistor. If there is one external from the drive in the cabinet I’d imagine it was sized for the task. If you need any help figuring out the parameters just shoot me a dm with the drive information, before I went into the office designing and supervising installion of process controls is pretty much all I did.
dynamic braking does not come up in the manual
there do seem to be places I can poke at to change how long it should take to decelerate.
and safety’s in place should I ask too much
Dynamic breaking just means that the motor is turned into a generator and the current it generates is shunted to the resistor bank where it’s turned into heat, the faster you dissipate the current the harder the motor breaks (like a generator under too much load). If there is a resistor in the drive cabinet it should be wired to do this electrically speaking. There should be a parameter that allows you to control deceleration rates.
thank you! I’m gonna bang my head against it for a bit. or maybe just run the fuge if the solvent is cold enough. if I get stuck I’ll hit you up.
I think I’ve located those
now to learn the button pushing sequence required to get it to do my bidding.
even though I can figure this out, it really helps to know I don’t actually have to
what’s the model number of the resistor? They list it as regenerative breaking in the manual. If you need any assistance just drop me dm
can’t find a label on the resistor, may need to demount it.
solvent is cold, so I’m a slave to the timer now.
yeah, making progress…I think.
manual says I didn’t set pr. 77 to “2” before my first attempt
ie: I tried changing stuff while it was still in “write disabled” mode!!
if I’m honest, part of the problem is that once I start changing stuff, the temptation to turn it up to 11 is going to be really hard to resist…
While I consider this an R&D machine, it’s also someone’s lively hood, so I’m trying to resist the voices in my head that want me to turn it up by 25% just so I can hear the new harmonics…
You can add a motor brake that will attach to the fan side of the motor, this will need to be energized via relay when the vfd stops and will physically stop the motor , adding a braking resistor to the vfd won’t do what you want for an a master electrician if you need further help dm me