PM-1236 motor issue

chuckorlando · Nov 2, 2014

You made the right call. If I have a motor or engine go south prematurely, I always feel uneasy with the same style replacement.

GA Gyro · Nov 2, 2014

Both of my PM machines were ordered with 3PH motors... added the VFD's.

mksj · Nov 6, 2014

Programing parameters and instructions for Hitachi WJ200 poster here: http://www.hobby-machinist.com/show...-to-the-control-switches-on-a-PM1340GT-lathe?

Hopefully you can use these parameters as a starting point for your PM1236. Let me know if you have any questions.

tino_ale · Jan 24, 2015

Ok update time :whistle:

I have received the Hitachi VFD along with the Leeson 3 phase motor.

I have wired just the two of them, on a bench just like a mockup, also with the 1k pot. I have wired the motor for low voltage. Then changed the few mandatory parameters to make it work, fired it up : it is alive !
So far so good!

Now I need to do all the wiring on the machine. I was going to wire it exactly like described in this PDF disconnecting the mechanical foot brake and adding the reverse jog selector.
I have noted the schematic noted in this PDF and for the most part I think I understand it but I realized I could not be easy on my gears and have a fast and strong emergency stop. So, I would like to make something slightly different and I could use your help.

I would like to have a normal operation brake setting, say 5 seconds, separate from an emergency brake setting that will be as fast as the VFD can take (I know I will need to source a braking resistor), 1 second or so. That emergency brake will never be used except, well, in case of an emergency.

The emergency stop has to be activated if :
- E-stop is triggered
- foot brake is activated
- gear cover is opened
- chuck guard is opened
Basically any danger situation triggers the emergency brake. Normal operation uses the soft stop to prevent wear and tear to my gears and make my lathe last for years

.

Does anyone know how I should wire this string of 4 interruptors ? The emergency stop has to override any other input including jog, and use a separate brake setting. Also after an emergency stop (any of the 4 interruptors), the lathe should not resume power unless I return to neutral first.

Has anyone done this before ?
Any advice welcome!

mksj · Jan 24, 2015

I do not feel that it causes any problem to have a 1 or 2 second stop time programmed in. Even with a 1 second programmed in the WJ200 (which is what I use), the faster the RPM the longer it takes to stop, so at least 2-3 seconds from the higher RPMs and it is very linear as opposed to jarring like the mechanical brake. (I set my deceleration to a linear line as opposed to the S curve). When you consider what the gears go through with the starting and stopping without the VFD, it should not be an issue for the gears with a VFD.

Should be very easy to have two different braking speeds, which schematic are you working off? I need to look at the programming, but one should be able to switch between a 1 step (quick) and a 2-step (default, slower) deceleration using an additional programmed input terminal.

mksj · Jan 25, 2015

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To use two different braking algorithms (short 1 second and long 5 seconds), connect a wire from terminal N-13 in the above diagram (any point after the last interlock switch) to the next unused VFD terminal input (assume this is 4). You could also add a toggle switch in that input wire line, so for something like threading, you hit the toggle to the open position to get 1 second braking.

[FONT=&amp]In the diagram above, this would be Input 4 (BR). Reprogram input 4 per page 4-22 of the manual, "Two Stage Acceleration and Deceleration" so set with option code "09". Set A093 to 4 seconds and set A094=0. Set first step of the deceleration F003 to 1 second (set F002 acceleration to 5 seconds, second acceleration time to A092 = 1 second). So whenever the relay is latched, and there is power to N-13, this signals the VFD to use 2-stage braking of 1+4 seconds. Anytime power from P24 is interrupted (or the signal to input 4 "BR" is broken), the machine would revert to 1 second braking (single stage). You could also still use the mechanical brake if you wanted to, you would just need the switch in the schematic that signals the motor to free run (no braking B091 setting 01 programmed to a separate input terminal), and this should engage when you press on the brake.[/FONT]

Let me know if this is clear, and if you want it added to wiring diagram/list of suggested VFD parameter changes.

tino_ale · Jan 26, 2015

Hello,

This is the schematic I would base my wiring on (PDF file) :

http://www.chaski.org/homemachinist/viewtopic.php?f=42&t=96363

Thanks for the suggestion. I think I understand how it works. I'll edit the schematic later and post it here for a last review before I start crimping wires :talktogod:

mksj · Jan 26, 2015

Schematic with dual braking adaptation. Do not really see the need for a forward reverse switch for the JOG. Let us know how it works out.

VFD Wiring Schematic Example with 2 speed braking.jpg

GA Gyro · Jan 26, 2015

mksj said:
Schematic with dual braking adaptation. Do not really see the need for a forward reverse switch for the JOG. Let us know how it works out.
View attachment 93449

Thx Mark... may adapt part of this to my 1340 when it gets here.

tino_ale · Jan 27, 2015

mksj said:
Schematic with dual braking adaptation. Do not really see the need for a forward reverse switch for the JOG. Let us know how it works out.
View attachment 93449

Looks perfectly fine, thanks !
I did not notice there was no light wiring before you added it, good eye!

I need to order all the missing parts :
- 3 x 1N4001 diodes
- 1 x 4-poles 24V relay
- 1 x 1k pot (got this one already)
- 1 x switch for reverse jog (I can see it usefull for taping in and out, etc)
- connections rail for all the 24V wiring

Looks like I have a plan
cheers

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PM-1236 motor issue

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