[How do I?] Wj200 Settings For Lathe W Braking Resistor

pstemari

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Does anyone have a firm understanding of the various parameters related to using a WJ200 with a braking resistor? In particular, I've not certain what the "braking duty cycle" is or what to set it to.

To complicate things, my lathe also has a foot brake. That's currently hooked into the e-stop circuit, connected with the safety mode mode GS1/2 inputs, and put the VFD into free-wheel stop. Unfortunately, once you release the foot brake the e-stop condition is cleared and the VFD happily goes back to controlled deceleration. I don't know what happens if you hold it long enough to come to a full stop or wait out the (current) 15 second deceleration setting.

The key settings I've identified are:

F002: acceleration time, currently 15 sec, would like to set it to <5 second
F003: deceleration time, currently 15 sec, would like to set it to 1-2 second

These are the ones puzzling me. Do they need to be set, and do I need to take the resistor value and allowed duty cycle into account (I'm using a 47 ohm 300W resistor).

B090: Dynamic braking usage ratio !! This is the one I'm most concerned about.
B095: BRD selection
B096: BRD activation
B097: BRD register (do they mean resistor?)

Other stuff of interest:

A039: jog stop, set to 4, controlled deceleration
A044: V/f characteristic curve, 00 - constant torque. Set this to sensorless vector control?

A051-A059: DC braking--??? Does this need to be looked at?

A061: Frequency upper limit, 72 Hz (based on motor nameplate spec)
A062: Frequency lower limit, 48 Hz (I'd like to lower this at some point)

A069: Acceleration hold frequency - ???
A070: Acceleration hold time
A154: Deceleration hold frequency
A155: Deceleration hold time

A081: AVR Function ?? disable during deceleration ?
A084: AVR deceleration gain ??

A097: Acceleration curve, 01 S-curve
A098: Deceleration curve, 01 S-curve

B050: Controlled deceleration on power loss?

B088: Restart mode after free-run stop
B091: Stop mode selection

B130-B134: Deceleration overvoltage suppression
 
I'm not going to be a lot of help since Mark Jacobs (mksj) on this site helped me with my setup BUT I am running electronic braking and a manual foot brake. On mine I replaced the foot brake switch with a double pole NO/NC switch. When the foot brake is used it triggers a freewheel command to the VFD so I can use the drum brake. Otherwise it uses electronic braking for everything else. Alternately the foot brake could be setup to trigger the electronic braking and the mechanical brake would have to be disabled. Attached is the parameter file mksj sent me that I used for programming the VFD. Not knowing how your lathe is wired it may not all apply.
 

Attachments

  • PM1340GT WJ200 Parameter File, Program Menu and Wiring Schematics 05-JUL-2015.pdf
    4.9 MB · Views: 56
Per what Jay posted, the parameter file addresses most of your questions and has comments on the side. I do not use the GS1/2 as part of my designs, if the E-Stop is hit, you want the lathe to stop as quickly as possible, about 1 second with a braking resistor, 2-3 seconds without. If you brake to aggressively without an additional external braking resistor, you will most likely get an over voltage error on the DC bus. When you add the resistor, it is automatically registered by the VFD, you do not need to change anything. With a braking resistor, 1 second is doable. I setup VFD on lathe to either have 1 stage braking (1 second) or 2 stage (3-4) seconds, set by a switch. The wiring is such that any fault, error, E-Stop or sensor stop automatically reverts the system to 1 second. The 1 second braking is very fast, and can put a lot of strain on the system, so I use 3 second most of the time. If threading or cutting to a fixed stop, then switch to 1 second. I use S curve acceleration, linear curve for braking, which is less likely to trip an over voltage error. The Dynamic braking ratio, I set this to the maximum, usually 10.0%. It is somewhat moot, it is the maximum amount of braking time allowed in % of use. Since braking is usually in 1-3 seconds, it represent an infinitesimally small time or %.

Most of your other questions are in the parameter file posted. You want sensorless vector control, set the motor parameter per you motor, maximum frequency I usually recommend 80 or 90 Hz on a standard 3 phase motor. Lower frequency I usually leave at 0, or something like 2 Hz. The usable speed range is something like 20-90Hz, sometimes you may want a very low speed to check TIR.

If you have a manual foot brake, than as Jay outlined, you can use either electronic VFD braking or mechanical, but not really both. If using the manual brake, you need to give the freewheel command to the VFD so it does not fight the mechanical brake. This is done as a dual pole foot switch which kills the VFD run command and sends a free wheel command to the VFD. The free wheel command is active till the motor stops. There are different ways of setting this up.
Mark
 
What I settled on is here: Lathe VFD Settings (WJ200). Some of the settings above only affect use of the analog input for PID control, not really applicable for the lathe. The keyswitch, e-stops, and mechanical brake all trip the GS function and freewheel stop. I figured that was exactly what the behavior was without a VFD and that I didn't want the VFD trying to drive the lathe down through a deceleration curve.

One thing I noticed earlier was that VFD doesn't treat the deceleration curve as an upper limit, but as a specific target. When I had the deceleration set to 15 sec and hit the footbrake, the lathe would freewheel and stop, but after the brake was released and the GS deactivated, it would resume "deceleration" and drive it back up to speed and continue slowing down at a controlled rate. Not an issue with deceleration set to 2 sec, though, since by the time you take your foot off the brake, the 2 seconds have already elapsed.

I did have to rerun the tuning in lowest gear. I found that it wasn't behaving well initially--so poorly, in fact , that I opened the headstock and inspected the gears, thinking there was a mechanical problem. Once I retuned it and changed to linear acceleration it was fine.

I also bumped the minimum frequency up to 36Hz, which seems to make it happier. Jog is set to 6 Hz, which works fine.
 
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