Invertek VFDs

detchells said:
Your post was perfect for me as well; I just got a Precision Matthews 1236, and went with a 3-phase motor and VFD, an Invertek E3 the same as you. Taking the support number from your post, I called and spoke with a tech named Jared, and he very quickly understood what I was wanting to do and answered all my questions. I agree, they have fantastic tech support, it was *WELL* worth the higher price vs a Chinesium model!

I’m setting up my drive the same as yours, where Fwd + Rev at the same time will do a fast stop, but I’m a bit confused by your description: wouldn’t tying the brake switch to both fwd/rev inputs mean that any time one normal switch closed, the other inout would see the closure also? I’d think that you would need a couple of diodes to prevent that from happening. (Or maybe your brake switch is DPST?)
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See if this helps. I’m not a double E so my electrical schematics may be pretty bad. I think you’re over complicating the circuit. Breaking it down to basics, you would have voltage at either the FWD or REV terminal on the VFD because the lathe is running. You would have no voltage at FWD if you’re in REV and no voltage at REV if you’re in FWD. Any wire connected to the FWD or REV terminal would also see voltage when the limit switch is closed because that’s essentially when the NO LS is doing, passing voltage through to the FWD or REV terminal.

Ok so now we’ve established that one of the two, but not both of the terminals will have voltage. To initiate a fast stop, the VFD needs to see voltage on BOTH FWD and REV terminals simultaneously. If you run a lead from the FWD and REV terminals to opposite sides of a NO LS, one side of that NO LS will have voltage when the lathe is operating. By closing that LS, you’re creating a pathway/condition in which both FWD and REV are provided voltage simultaneously. This NO LS is your brake switch.

When the brake is pressed, fast stop initiates and the lathe stops. The VFD will require that both the FWD and REV terminals are de-energized before the VFD will put power to the motor again. Because your apron lever is still in either FWD or REV, you have not met the reset condition and the VFD will not energize the motor. To reset, you just take the apron lever back to off and then back in to FWD/REV. This is a great safety feature.

Sorry I didn’t use specific Invertek terminal numbers/etc. I’m out right now and don’t recall by memory what each terminal is named.
 

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Ceej0103 said:
Ok so now we’ve established that one of the two, but not both of the terminals will have voltage. To initiate a fast stop, the VFD needs to see voltage on BOTH FWD and REV terminals simultaneously. If you run a lead from the FWD and REV terminals to opposite sides of a NO LS, one side of that NO LS will have voltage when the lathe is operating. By closing that LS, you’re creating a pathway/condition in which both FWD and REV are provided voltage simultaneously. This NO LS is your brake switch.

When the brake is pressed, fast stop initiates and the lathe stops. The VFD will require that both the FWD and REV terminals are de-energized before the VFD will put power to the motor again. Because your apron lever is still in either FWD or REV, you have not met the reset condition and the VFD will not energize the motor. To reset, you just take the apron lever back to off and then back in to FWD/REV. This is a great safety feature.
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Ah! DUH, you're right, I was over-complicating it - or at least didn't realize that I could just use the voltage on one of the terminals to bridge to the other one. I was thinking in terms of the NO emergency stop switch connecting both to the +V, meaning that both would be tied to the same terminal. Your approach is super-simple, thanks!

(Hmm, OTOH the emergency-stop switch on the front panel of my lathe is currently an NC contact. I had been planning to just put this in series with the +V used to provide power to the FWD/REV contacts. Hitting the button would open the contact and stop the lathe, but only at the normal turn-off ramp rate. I'll see if the switch itself might actually be a SPDT so I can use the other side of it for the NO function. If not, I may need to add a relay or use a transistor, resistor and pair of diodes to invert the signal.)

Thanks again so much for the quick and insightful reply - I actually have a Masters in EE, but sometimes it's not how much you know, it's how you think ;-)
 
detchells said:
I'll see if the switch itself might actually be a SPDT so I can use the other side of it for the NO function. If not, I may need to add a relay or use a transistor, resistor and pair of diodes to invert the signal.)
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Or just get a new switch that's NO and go from the NO brake switch in to the E-Stop switch. If your lathe is like mine, the brake cam/switch is over on the left of the machine near the motor and your E-Stop is over on that side of the machine, too. A parallel configuration would mean each of the NO switches (e-stop/brake) would always have voltage on one side when the machine is operating and closing either of the switches would backfeed/bridge back to the VFD's DI1 or DI2 terminals thereby providing voltage to both DI1 and DI2 simultaneously. I think I'm using Macro 5, which also includes analog input at DI4/AI1 for my POT.

BTW, should have mentioned this prior. Fast Stop, at extremely high RPM, will likely cause over voltage errors. I know from experience. If you're running high RPM (1000+) you'll need to adjust your fast stop to not be so fast (play around until it doesn't give you an over voltage error). If that's not good enough, which 3 seconds isn't really good enough if an emergency occurs, you should grab a braking resistor. This will allow you to make that stop near instant without hitting over voltage limits on the VFD. Mark (user MKSJ) is the VFD wizard around here. He recommended the following resistors for my unit. I'm using the 5 HP (Frame Size 3) VFD. There's a table in the manual in section 9. Technical Data that tells you the Recommended Brake Resistance for each of their OptiDrive E3 VFD sizes. A call to the technical support line would get you that information rather quickly, as well. I'm sure mouser, the online store Mark recommended would also have the variant you require if you're not also using the 5HP VFD.




Let's see some pics of the setup! You show me yours and I'll show you mine ;)
 
Ceej0103 said:
Or just get a new switch that's NO and go from the NO brake switch in to the E-Stop switch. If your lathe is like mine, the brake cam/switch is over on the left of the machine near the motor and your E-Stop is over on that side of the machine, too. A parallel configuration would mean each of the NO switches (e-stop/brake) would always have voltage on one side when the machine is operating and closing either of the switches would backfeed/bridge back to the VFD's DI1 or DI2 terminals thereby providing voltage to both DI1 and DI2 simultaneously. I think I'm using Macro 5, which also includes analog input at DI4/AI1 for my POT.
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My lathe doesn't have a brake pedal; I think just having the normal decel ramp time on the drive set to 3 or 4 seconds will be fine without having a separate brake switch. I want to use the current (NC) e-stop switch because it's one of those huge red locking pushbuttons that'll be harder to miss in a panic. I'm gonna pull the panel in a few minutes and see if it's actually SPDT inside or if I need to do something to invert its signal.
Ceej0103 said:
BTW, should have mentioned this prior. Fast Stop, at extremely high RPM, will likely cause over voltage errors. I know from experience. If you're running high RPM (1000+) you'll need to adjust your fast stop to not be so fast (play around until it doesn't give you an over voltage error). If that's not good enough, which 3 seconds isn't really good enough if an emergency occurs, you should grab a braking resistor. This will allow you to make that stop near instant without hitting over voltage limits on the VFD.
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Yeah, I'd known about that. Your note here is very timely, though, as I've been waiting for Invertek to reply back about resistor sizing. I didn't realize they had a table in the manual; the printed copy just says to ask your supplier for a recc. At your suggestion, I looked at the PDF and found the resistor sizing info there.
Ceej0103 said:
Mark (user MKSJ) is the VFD wizard around here. He recommended the following resistors for my unit. I'm using the 5 HP (Frame Size 3) VFD. There's a table in the manual in section 9. Technical Data that tells you the Recommended Brake Resistance for each of their OptiDrive E3 VFD sizes. A call to the technical support line would get you that information rather quickly, as well. I'm sure mouser, the online store Mark recommended would also have the variant you require if you're not also using the 5HP VFD.
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Mine's the 3HP model, so it looks like 50 ohm is what I'll want.
Ceej0103 said:

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Wow, those are beefy, at 500 watts :-0 Given that my machine is smaller (1.5HP motor), I think I can probably get away with 200-250W.
Ceej0103 said:
Let's see some pics of the setup! You show me yours and I'll show you mine ;)
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Happy to! I have some figuring out, wiring and packaging to get sorted before it'll be fit for public sharing :)
I've got a steel control box that I'm gonna mount a line filter, the speed pot and a type-B circuit breaker in, and mount both it and the drive on the sheet metal apron between the lathe mount pedestals. It's tucked well under the chip tray, so I think would be safe from coolant, etc, and I'm not likely to bump it. I'll probably make a separate sheet metal shield to go above the drive itself as added protection.

(I dunno though, I need to make some sort of a mount for the DRO, might somehow combine that with drive and control panel. Really, though, I'd only need the speed pot and a tach readout up top, so that may be what I do. I'm staring at it and pondering, with the knowledge that I'll almost certainly end up redoing things once I start actually using the lathe :) I need to look at some pics and see how people typically mount DROs for maximum convenience...)

I just got the lathe up onto its stand and leveled the other day, am still cleaning the anti-rust goo off of it, so it'll be a little bit yet :)

Thanks again for all the info!
 
If you like to home brew, you can use a 50 ohm stove element as a braking resistor. They are rated at 800, 1000, and 1200 watts. Mine cost 40$ CDN.
 
Hi All,

When it comes to understanding how to wire the terminal strip of the Invertek Optidrive E3, I recommended first learning the Macro Functions reference tables from the user guide. Once you wrap your head around how to read it, the rest is straight forward.
 
The diodes would be necessary without the mechanical interlocks provided by the cams. This is at least what it sounds like. An alternative to diodes is to create your own interlock with extra contacts on each of the pilot devices should they be of that type.
 
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