Author Topic: fitment of VFD to Warco GH1322  (Read 12127 times)

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
fitment of VFD to Warco GH1322
« on: May 29, 2014, 09:00:43 PM »
Hi All
This write up  was written at the behest of Arbelest following  a post made on another thread.
It documents (with hindsight) the practical exercise carried out whilst endeavouring to solve the problems brought about by uninformed decisions made whilst upgrading my lathe!
I did not take photos at the time but I will where possible take some retrospectively.
in common with many engineers if asked “what is the advantage of a 3 phase supply?” will probably answer “improved motor torque and control” with little hesitation and in the same breath acknowledge that few hobby workshops have the luxury of this supply on tap. Having decided that this attribute was a desirable one I decided to make this a feature of my next lathe purchase not fully at the time realising the implications of my decision.
As far as lathe ownership is concerned the past ten years  has  proven to be a fairly steep learning experience as progression from my original purchase a  7x14 Real Bull mini - lathe  to a Chester 9X20  and more recently to a Warco 1322 gear head lathe took place.
The decision to go with the Warco GH1322 gear-head lathe was influenced to a great extent by the fact that it was advertised as being obtainable with a three phase motor fitted as an option. Given expectations of added torque I opted for this machine. It was delivered at my behest with a dual voltage  (415/240) 3-phase motor fitted, which in the absence of three phase electrics  in the workshop meant that an alternate means of supplying 240volt 3 Ø was required.
Various quotes from local electricians had put the installation of a 240volt 3Ø system in my workshop at an eye watering cost of well over £1000, forcing an alternative approach to solving the problem as by now I was beginning to panic.
At the Midland Engineering show last year I had been fortunate  enough to discuss the pros and cons of inverter use with Peter from Transwave, a Birmingham based company specialising in phase conversion products. He suggested that a Jaguar VXR inverter with a pendant control would provide all basic lathe control and solve the immediate supply problems for under £300 a no brainer really!

Having taken delivery of both lathe and inverter  the fun really began, starting with the stark realisation on reading the manual that most if not all of the basic facilities of the lathe must to be either modified or sacrificed, for example the mechanical levers that conveniently control the spindle direction  cannot be utilised in their original configuration. Other facilities such as the spindle brake, chuck guard interlock, emergency stop button, gear cover interlock and coolant pump  were apparently not operable in the basic lathe configuration whilst using the inverter.
The reason for this is technically fairly straight forward, the output from the inverter controlled by the pendant must be wired directly to the motor, no switched path between the inverter and the motor is permissible.
Thus  a complete rethink as to how the basic lathe electrics were to be configured was required.

this is an image of the relevant lathe fitted with a 2HP 220volt 3phase motor.
to be continued......
regards
Terry  T
« Last Edit: May 30, 2014, 09:55:27 PM by minerva »

Arbalest

  • Guest
Re: fitment of VFD to Warco GH1322
« Reply #1 on: May 29, 2014, 10:08:06 PM »
Thanks for the write up so far Terry!  ;)

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #2 on: May 30, 2014, 02:44:34 PM »
proceeding...
At the outset examination of the original circuit diagram revealed that essentially three voltages were required for operation of the lathe in its original form:

viz.
A 415volt 3phase  input for motor operation ( L1,L2,L3 ), a 24volt ac supply  from the transformer (Tc) for use by the ac contacters involved in the three phase switching for direction control of the motor. And finally a 240 ac supply is required for  the DRO fitted to the lathe as an optional extra.(originally from the transformer but not available in new configuration ,see below)
Further examination of the circuit diagram revealed the basic problem, the control voltage of 24volts is derived from a transformer fed from the designed 415 volt input, reducing the input to 240 volts unsurprisingly drops this voltage to approximately 12volts which is no where near high enough to operate the various  24v control contacters employed in the basic lathe configuration as delivered from Warco.
In a rather perverse fashion the realisation of this fact provided a partial  solution as to the way forward and coupled with a  quote from the pendant fitting instructions viz. “ any further stop/start connection of limit switches etc. may be achieved by breaking the 28volt+. Pink wire to the inverter and inserting normally closed circuit switches as required in series with the pendant”paved the way for an almost total  solution to the posed dilemma.
to be continued...
Regard Terry T
« Last Edit: May 30, 2014, 02:58:39 PM by minerva »

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #3 on: May 30, 2014, 05:11:47 PM »
apologies if some of this appears basic but please remember some of our members are still at the beginning of their journey!

The  practical solution
From a primarily electronics/electrical engineers perspective the problems posed from the outset were not insurmountable however as mechanical engineers the thought of re-designing and rebuilding a brand new lathes electrical control box might seem a little  daunting. Let me say however that essentially having mastered a couple of basic electronic control methods a practical solution is readily achievable by exponents of both disciplines. All that is needed is the confidence to proceed.
In order to achieve our objectives  only two of the original contactors were needed specifically KM1 which I used for switching the inverter input supply and KM3 which I retained as the coolant motor contactor although as you will see later it became prudent to change the supplied 3phase coolant motor to a new single phase item.
Firstly an understanding of simple relay / contactor control is required and the  simple circuit shown below provides  the method whereby a high voltage supply may be switched safely utilising a relatively low  voltage, details of the basic circuit employed is as follows:



With the control switch in the open circuit position no current flows in the contactor coil and the main feed contacts remain in the open circuit position, closing the control switch permits current flow through the contactor coil and the main contacts close thus connecting the high voltage across the contactor .  The original lathe wiring calls for a 24volt control supply which operates several contactors this supply however is as shown above not available using the installed transformer whilst using a 240volt input. For motor control we only need to use one of the existing a/c contacters ( as stated above I used  KM1 and its associated thermal relay ). In order to use this contactor a 24volt supply is required. I made use of a  transformer from my scrap box (240v primary and 28-0-28 secondary)which was mounted in the main power enclosure. A 30amp terminal block was also fitted to the main power enclosure and  fed the primary 240 volt mains mains input , this enabled the 240 volt supply to be distributed in a much more efficient fashion.
Using the simple circuit outlined above and a  spst switch (single pole single throw switch) mounted on the case of the control box the input side of the inverter on operation of the switch is connected to the mains supply. The motor may therefore be hard wired directly to the motor as per the original brief/requirement. The pendant may now be fitted in accordance with the supplied  instructions and the lathe may be used in a normal manner with control over stop, start ,speed ,direction and the very handy “jog” function being controlled from the standard pendant as purchased with the inverter. However there is still some way to go.

The various “stop/interlock” conditions mentioned above cannot at this stage be utilised using  “motor power interrupt” methods. They are of course desirable indeed  from a health and safety perspective mandatory and the pendant connection instructions indicate the way that they can be incorporated within our inverter fit . From the pendant fitting instructions It states that “additional limit switches may be added by breaking the pink wire (24volt+)to the inverter and inserting the various normally closed switches in series” thus operation of any switch in the chain will stop the motor.
Diagrammatically this concept is shown as :-

« Last Edit: May 30, 2014, 09:38:43 PM by minerva »

Arbalest

  • Guest
Re: fitment of VFD to Warco GH1322
« Reply #4 on: May 30, 2014, 05:22:05 PM »
Basic is good Terry, at least as far as I'm concerned!  :naughty:

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #5 on: May 30, 2014, 08:55:18 PM »


The switches in question are easily identified on the lathe or from the circuit diagram SB1 is the latched emergency stop (ie.following operation the switch has to be reset physically before the lathe can be restarted) it is mounted on the original control panel. The chuck guard interlock is designated SQ1, the foot brake SQ4, leaving the gear cover interlock as SQ5. once identified within the original enclosure the switches are easily disconnected from the main terminal block and re connected in "daisy chain" fashion.

At a practical level this is quite simply achieved by employing a “chocky block” style terminal block into which the various switches are wired and the links between hard wired, the daisy chain is then inserted between the +28volt terminal on the inverter and the disconnected pink wire. this extended terminal block was mounted inside the main power enclosure (photo to follow)
The next stage is that of restoring the functionality of the lathe mechanical forward and reverse lever. This requires a little thought and slight modification to the standard pendant circuitry.
In use the lever depending upon its position selects one of two ganged micro-switches  (SQ2 or SQ3 ) either Fwd.  Rev.  or Off,  however  in reality only two of these states require our attention as the -Off-  selection is merely an open circuit condition. Investigation using a multimeter identified  at the main terminal block terminals 7 & 8 as the switched leads with terminal 4 as the common. That is to say that when Fwd. Is selected  terminal 7 is connected to terminal 4 and when Rev. is selected terminal 8 is connected to terminal 4 . ie it is a “changeover” situation. All that is required to achieve our objective is to isolate these three  wires from the main terminal block to another chocky block and wire the two possible switch positions so that they operate in parallel with the pendant Fwd./Rev switch. The following diagram I hope clarifies the solution. A  dpdt switch effectively acts as an either/or situation allowing control of the lathe to be selected to either pendant or lathe control.
to be continued......
« Last Edit: May 30, 2014, 09:15:35 PM by minerva »

Offline Don1966

  • Full Member
  • *****
  • Posts: 6817
  • Columbia, MS
Re: fitment of VFD to Warco GH1322
« Reply #6 on: May 31, 2014, 02:51:02 AM »
Hi Terry I think your doing a great job of explaining and basic is a good place to start for the less knowledgable. And thanks for taking the time to post this and I am sure some will find it very useful. My I make one suggestion on your control circuit?

Regards Don

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: fitment of VFD to Warco GH1322
« Reply #7 on: May 31, 2014, 01:53:40 PM »
Hi Terry I think your doing a great job of explaining and basic is a good place to start for the less knowledgable. And thanks for taking the time to post this and I am sure some will find it very useful. My I make one suggestion on your control circuit?

Regards Don

Hi praise indeed Terry....Don knows his stuff!

I would like to add that your style and cadence is very easy to read and follow.....Nice Post! Please continue!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #8 on: May 31, 2014, 10:18:26 PM »
Hi Don, Dave,
many thanks for the plaudits.
Don,feel free to add any comments you feel necessary  bearing in mind I have intentionally over simplified thus far and hope to put in the bells and whistles before we're through.

Regards
Terry T

Offline Don1966

  • Full Member
  • *****
  • Posts: 6817
  • Columbia, MS
Re: fitment of VFD to Warco GH1322
« Reply #9 on: May 31, 2014, 11:10:22 PM »
Hi Terry thanks, I just didn't want to jump in without your approval. The only thing I wanted to add is about your control circuit, that putting the ESTOP in the control circuit I kind of avoid. Instead use the ESTOP in the place of your toggle switch to remove power to the drive. Electronics have a bad habit of turning themselves on. With the ESTOP controlling the mains power you have a way to secure your lathe when finished for the day and should thunder storms come your way your VFD is safe. If glitches or failures turn your lathe on at the wrong time the ESTOP will stop it.

Regards Don

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #10 on: May 31, 2014, 11:50:16 PM »


this c-o-cad shows in diagrammatic form both the modification to the pendant and the inclusion of the various interlocks discussed above.
The practical methods employed incorporating the circuit within the overall scheme of things involved the use of as mentioned above a double pole double throw change over switch and a 12mm flanged conduit to permit the change lever wiring access to the pendant. Both being mounted through the pendant case the conduit through the bottom and the c/o switch on the side.(pics to follow).
 Actual connections were soldered to the existing internal components of the pendant with the exception of the common wire from
terminal 4 which I connected to the common wire of the Fwd/Rev. utilising a pick-a-back crimped connector.
At this point I made the decision to remove the Jog button from the original lathe panel leaving the pendant mounted control which still operates regardless of the machine/pendant switch position.

to be continued.....
regards Terry T

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #11 on: June 01, 2014, 10:36:52 PM »
continuing...



this photo shows the finished pendant, the second ferrule on the right carries the wiring from the machine lever micro-switches and the change over switch clearly marked on the left hand side.

Finally in order to bring the lathe up to full specification all that remains is for the coolant system to be modified and the machine light commisioned. The fitted inverter will only drive one motor therefore a second inverter must be purchased to drive the coolant pump, or as an  alternative  my strategy was to change the pump supplied with the machine for a single phase  240volt pump. (sourced from RDG) this proved to be the cheaper option.
A duplicate of the control circuit used to control the lathe drive motor was employed to control the coolant pump  ie. A 28 volt supply is fed to one side of the operating coil of KM3 the other being returned to earth via the coolant switch. On switch on  the now 240 volt supply is fed across the contactor to the  pump supplying the required lubricant from the suds sump.
commisioning of the machine light however was a different story. The ever expanding demand upon the 28volt supply proved a little too much for my scrap box transformer, operation of the machine light promptly loaded the 28volt supply to a point where both power contacters dropped out of circuit effectively shutting the machine down. The problem was easily solved however by adding a separate supply for the lamp circuit.



This photo shows clearly the inverter mounted on top of the main power enclosure and the it can be seen that the original lathe jog button has been replaced by a 240volt indicator lamp and although only just visible a 28 volt indicator bulb is fitted as an indication that 28volts is available. Two cable conduits in the side of the power enclosure can be seen taking the cables from the power enclosure to the inverter.
to be continued....
regards
Terry T

 
« Last Edit: June 02, 2014, 07:23:36 PM by minerva »

Offline minerva

  • Full Member
  • ****
  • Posts: 16
  • Grantham UK.
    • minervas miscellany
Re: fitment of VFD to Warco GH1322
« Reply #12 on: June 02, 2014, 11:04:44 PM »
continuing,

The machine has been in use for some two weeks now and it has to be said it is a joy to use and has exceeded all expectations. The jog facility in conjunction with the lathe direction lever has been used on a couple of occasions with great success for powered tapping and threading which has made the whole exercise worthwhile.
I have as yet not had time to make a full drawing of the refit circuit but suffice to say I will post when complete.

In retrospect several thoughts have occurred and I append the following  in no particular order and hope they may serve to assist anyone attempting the same exercise:

1). The spindle brake fitted to the GH1322 is a combination of both electrical micro-switch operation  and mechanical brake shoe set up, operation of the micro-switch disconnects  the inverter output and pressure on the  the mechanical brake acts directly upon the spindle to affect the spindle slow down. With little or no effect upon the electronics of the inverter.

2).The emergency stop button as fitted, (see photo above) if pressed latches in the off condition
until manually reset by turning the switch clockwise and as mentioned by Don may be
employed in alternative positions within the lathes control circuits his comments are very
valid  and perhaps if inserted in series  with the single pole switch in the inverter control
diagram  a belt and braces situation exists to cover all eventualities.

3). The original  lathe “jog button was removed and the pendant “jog” button retained, it operates regardless of the position of the pendant changeover switch. The hole left in the the fascia was filled utilising a 240volt indicator giving an indication when mains supply is connected. I also fitted a 28volt indicator as visible indication of all active supplies.

4). The A/C contacters used by the manufacturers of the GH1322 have operating  coils designed for 24volt operation necessitating  a 24volt supply which was the way I chose to go however an alternative option from the outset is to replace the fitted contactors with coils rated for 240 volts operation  this obviously involves extra expense (they are around £25 apiece and two would be required.) this would make the original 28volt wiring and  transformer redundant. The lathe only requiring a mains connection. Although the machine lamp would have to be replaced with a 240volt version (further expense)

5). The original circuit employed  (see circuit above) employed 3 fuses for the three phase motor feed and two for the  24 volt circuits. (the lamp circuit I fused separately)



to be continued.....
regards Terry T
« Last Edit: June 02, 2014, 11:21:25 PM by minerva »

Offline John S

  • Full Member
  • ****
  • Posts: 141
Re: fitment of VFD to Warco GH1322
« Reply #13 on: June 03, 2014, 09:53:50 AM »
I am a bit  nonplussed on why all the wiring changes ?
I have done 3 of these so far on very similar machines and used the normal stop start switch on the apron and kept all the same interlocks.

All that was required was to break the interlock circuit away from the 24v transformer and link it to the logic voltage on the inverter.

Not counting motor change if needed from single to 3 phase and a length of new cable from inverter to motor, it usually takes less than an hour.
John Stevenson, Nottingham , England

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: fitment of VFD to Warco GH1322
« Reply #14 on: June 03, 2014, 10:24:30 AM »
Do you have a wiring diagram John?

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal