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- Jun 12, 2014
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I previously outlined the use of new contactors to use to switch the VFD inputs when doing a basic 3 phase VFD lathe conversion, this retains the same functions (and interlocks) as the stock lathe and should operate the same. The VFD adds speed control, and acceleration deceleration control. In order for the manual foot brake to work correctly, one should replace the single pole brake limit switch with a dual pole limit switch with one NC and one NO contact blocks. The NC is used for the stock 24VAC wiring connection, the NO is used to activate a VFD input and issue a free run command (no VFD braking). Be forewarned, there seems to be multiple control system/wiring used on the various 1440GT's I have seen, so this is a concept idea and should only be attempted if you understand and can following the wiring for your 1440GT. Otherwise, I would recommend going with an RPC. Before making any modifications I would contact the lathe manufacturer as to how it will effect your warranty, in most cases it voids anything electrical when any mods are done. Use this information at your own risk.
I have done a number of full control systems for the PM 1236, 1340GT and the 1440GT, as well as other machines. The PM1440GT was a more complicated full replacement system, and although I did a full control system build recently, it is not something I want to do again. In the most recent system, the VFD is mounted in the headstock cabinet behind the control cabinet. It makes for a very clean simple install and one saves in not having to do a separate VFD enclosure. I am providing a WJ200 parameter file as a starting point and some older schematic designs, the new system is more complicated. The tachometer and sender I wired to the main control board, the speed pot is in the tachometer enclosure. The stock switches and cabling are replaced, but the same 4 switch holes are used in the front panel, a 1/4 hole is used for setting 1 or 2 stage braking. The design below re-configures the stock brake switch to normally open, when the manual brake is engaged it triggers a braking relay which disconnects the power relay latch/VFD signals and sends a separate free run command to the VFD. The spindle lever must be reset to the stop position for the system to be reset.
One install where the VFD was mounted horizontally, but I recommend vertically on L brackets or a 90 degree back panel attached to the bulkhead wall. You can add a power disconnect to the front or side of the headstock base. The braking resistor is also mounted in this space.
I have done a number of full control systems for the PM 1236, 1340GT and the 1440GT, as well as other machines. The PM1440GT was a more complicated full replacement system, and although I did a full control system build recently, it is not something I want to do again. In the most recent system, the VFD is mounted in the headstock cabinet behind the control cabinet. It makes for a very clean simple install and one saves in not having to do a separate VFD enclosure. I am providing a WJ200 parameter file as a starting point and some older schematic designs, the new system is more complicated. The tachometer and sender I wired to the main control board, the speed pot is in the tachometer enclosure. The stock switches and cabling are replaced, but the same 4 switch holes are used in the front panel, a 1/4 hole is used for setting 1 or 2 stage braking. The design below re-configures the stock brake switch to normally open, when the manual brake is engaged it triggers a braking relay which disconnects the power relay latch/VFD signals and sends a separate free run command to the VFD. The spindle lever must be reset to the stop position for the system to be reset.
One install where the VFD was mounted horizontally, but I recommend vertically on L brackets or a 90 degree back panel attached to the bulkhead wall. You can add a power disconnect to the front or side of the headstock base. The braking resistor is also mounted in this space.
Attachments
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PM1440GT Basic Wiring Changes for using the Contactors to switch the VFD inputs 23 DEC 2017.pdf4.7 MB · Views: 658
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1440 GT VFD Schematic with external 24VDC PS Jog rev date 3-17-2016.pdf1,001.4 KB · Views: 559
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PM1440GT BASIC VFD PROGRAMMING USING THE STOCK CONTROL SYSTEM AND CONTROLS.pdf3.2 MB · Views: 507
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