Jim S.
Hot Rolled
- Joined
- Sep 4, 2003
- Location
- South Carolina
There have been several threads in this forum on converting HLV-H lathes to VFD power. This post is to show my experience totally rewiring my lathe to be powered by 230V single phase input with VFDs to provide 3 phase generation.
After watching the local market for years for an affordable HLV-H, I recently bought one that had been listed for several years but remained unsold, likely because it was 440V and in terrible cosmetic condition. I could not inspect it under power, which turned out good because the threading gear chain and leadscrew were packed with congealed grease and shop grime which may have damaged things if powered. Underneath, though, I eventually found things in near pristine condition with evidence that the threading system was likely never used. The deal was made even better with the discovery of over $1500 (conservatively) worth of unlisted tooling and step chucks/closers.
To the point, though, I needed to configure it for 240V single phase input. My approach was to gut the electrical box of all but a couple components and install a 3KVA 240V -480V transformer to power two VFDs with single phase. The VFDs I chose are Allen Bradley 160BA series C models which allow single phase input, have lots of control configuration options and are very affordable in the 460V versions. All total, the conversion cost $200 which included two VFDs, a braking resistor, and several AB 800T switches and a potentiometer. Not included is the transformer which I acquired years ago as a working take out just for this sort of eventuality.
I chose the VFD route for several reasons, primarily because it would cost no more that stepping up my RPC output with a 3 phase transformer as well as modernize the lathe controls (electronic vs primarily electro-mechanical) and also provide a wider range of variable spindle speed. Importantly, it retains low spindle speed Hp by maintaining the functionality of the reeves type variable speed system, in effect increasing the available spindle speed range on both ends without losing low speed loss of power. Additionally, the conversion retains the most important functions via their OEM handles/switches with a couple minor exceptions noted below.
The conversion specifics involved removing all the control relays and overload devices with associated wiring, retaining primarily the disconnect switch/fuse, control transformer and one control voltage relay. The control Xformer was rewired for 240V input and directly powers the relay and on/off controls. When power is switched on, the control relay powers up the 240-480V transformer and the 130V single phase for the carriage drive system. The internal VFD analog controls were wired through the control panel switches, spindle interlock and drum switch to retain OEM like functionality. The only significant deviations follow: 1. A spindle motor speed potentiometer was added to the control panel; 2. The two reeves type variable speed faster/slower push buttons were replaced by a single momentary return-to-center knob; 3. A stop button was added to the control panel to function as e-stop as well as to clear any VFD faults encountered; 4. The slow-off-high lever on the front of the headstock was rewired to become rev-off-fwd. This was enabled because the motor only utilizes the high speed windings. Thus, what amounts to "plug reversing" is available via that control handle; 5. The control switch for coolant was eliminated because I will not use coolant, though it could easily be fitted in the future.
The results have been entirely satisfactory. The overall wiring is considerably simplified and retains essential motor protection through the VFDs. I have several other machines powered through these VFDs and they have performed flawlessly for many years.
Pictures show the control panel (yet to be painted/labeled), the electrical box and the components/wiring removed. Gutting the box provided plenty of room for the two VFDs and braking resistor. I wish I had taken a picture of the box before modification.
Jim S.
After watching the local market for years for an affordable HLV-H, I recently bought one that had been listed for several years but remained unsold, likely because it was 440V and in terrible cosmetic condition. I could not inspect it under power, which turned out good because the threading gear chain and leadscrew were packed with congealed grease and shop grime which may have damaged things if powered. Underneath, though, I eventually found things in near pristine condition with evidence that the threading system was likely never used. The deal was made even better with the discovery of over $1500 (conservatively) worth of unlisted tooling and step chucks/closers.
To the point, though, I needed to configure it for 240V single phase input. My approach was to gut the electrical box of all but a couple components and install a 3KVA 240V -480V transformer to power two VFDs with single phase. The VFDs I chose are Allen Bradley 160BA series C models which allow single phase input, have lots of control configuration options and are very affordable in the 460V versions. All total, the conversion cost $200 which included two VFDs, a braking resistor, and several AB 800T switches and a potentiometer. Not included is the transformer which I acquired years ago as a working take out just for this sort of eventuality.
I chose the VFD route for several reasons, primarily because it would cost no more that stepping up my RPC output with a 3 phase transformer as well as modernize the lathe controls (electronic vs primarily electro-mechanical) and also provide a wider range of variable spindle speed. Importantly, it retains low spindle speed Hp by maintaining the functionality of the reeves type variable speed system, in effect increasing the available spindle speed range on both ends without losing low speed loss of power. Additionally, the conversion retains the most important functions via their OEM handles/switches with a couple minor exceptions noted below.
The conversion specifics involved removing all the control relays and overload devices with associated wiring, retaining primarily the disconnect switch/fuse, control transformer and one control voltage relay. The control Xformer was rewired for 240V input and directly powers the relay and on/off controls. When power is switched on, the control relay powers up the 240-480V transformer and the 130V single phase for the carriage drive system. The internal VFD analog controls were wired through the control panel switches, spindle interlock and drum switch to retain OEM like functionality. The only significant deviations follow: 1. A spindle motor speed potentiometer was added to the control panel; 2. The two reeves type variable speed faster/slower push buttons were replaced by a single momentary return-to-center knob; 3. A stop button was added to the control panel to function as e-stop as well as to clear any VFD faults encountered; 4. The slow-off-high lever on the front of the headstock was rewired to become rev-off-fwd. This was enabled because the motor only utilizes the high speed windings. Thus, what amounts to "plug reversing" is available via that control handle; 5. The control switch for coolant was eliminated because I will not use coolant, though it could easily be fitted in the future.
The results have been entirely satisfactory. The overall wiring is considerably simplified and retains essential motor protection through the VFDs. I have several other machines powered through these VFDs and they have performed flawlessly for many years.
Pictures show the control panel (yet to be painted/labeled), the electrical box and the components/wiring removed. Gutting the box provided plenty of room for the two VFDs and braking resistor. I wish I had taken a picture of the box before modification.
Jim S.
