Guys,
I've just recently got to a working stage the conversion to 3 phase motor with a VSD for my C6 lathe.
The VSD I am using is a Danfoss VLT 4kVA unit which requires 3 phase 415V input. Inspired by an old post by Brobdignagian, I have successfully powered the VSD from 240V single phase through a 240V to 415V 1.5kVA step up transformer with the two wires connected to L1 and L2. Phase imbalance trip setting was changed to warning only. As the motor I'm using is only 0.75 kW (at the moment, for testing purposes) the derating of the VSD still provides plenty of capacity.
The lathe controls have been transferred to a new control box with push-buttons for FWD, REV, JOG and STOP buttons, with a speed control pot. Additionally, I have included switches for the coolant system pump and the worklight. The lathe internal safety interlocks and emergency stop button have been included in the controls, and drop power to the control box VSD controls.
Latching relays for FWD and REV were needed with this VSD to allow push button control.
The Stop button can be momentarily pressed for coast-down to stop, or held in for DC braking stop.
The motor was mounted externally to the lathe to minimise disturbance to the original parts (in case I need to restore the original setup), and so the original motor has been replaced by an idler shaft driving the original pulley arrangement of the lathe.
The setup seems to have adequate power for this lathe from about 25Hz to 100Hz (lathe rigidity seeming to be the limiting factor with metal removal rate). This gives a speed range in the outer high speed pulley position of 350 RPM to 1400 RPM, and in the low speed outer pulley position of 70 RPM to 280 RPM.
The transformer and VSD should have enough capacity to upgrade the motor to about 1.5kW
The larger motor would give better overlap of high/low speed ranges, but presently I can use the other 4 pulley positions if needed.
The new drive runs much more smoothly and a bit quieter at all speeds than the original drive setup.
Some picture attached showing the setup, rough electrical schematic, and the temporary belt tensioner...
Andrew.
DSCN1286.jpg
DSCN1283.jpg
DSCN1282.jpg
DSCN1280.jpg
DSCN1279.jpg
DSCN1278.jpg
DSCN1276.jpg
DSCN1275.jpg
DSCN1274.jpg
DSCN1273.jpg
DSCN1284.jpg
I've just recently got to a working stage the conversion to 3 phase motor with a VSD for my C6 lathe.
The VSD I am using is a Danfoss VLT 4kVA unit which requires 3 phase 415V input. Inspired by an old post by Brobdignagian, I have successfully powered the VSD from 240V single phase through a 240V to 415V 1.5kVA step up transformer with the two wires connected to L1 and L2. Phase imbalance trip setting was changed to warning only. As the motor I'm using is only 0.75 kW (at the moment, for testing purposes) the derating of the VSD still provides plenty of capacity.
The lathe controls have been transferred to a new control box with push-buttons for FWD, REV, JOG and STOP buttons, with a speed control pot. Additionally, I have included switches for the coolant system pump and the worklight. The lathe internal safety interlocks and emergency stop button have been included in the controls, and drop power to the control box VSD controls.
Latching relays for FWD and REV were needed with this VSD to allow push button control.
The Stop button can be momentarily pressed for coast-down to stop, or held in for DC braking stop.
The motor was mounted externally to the lathe to minimise disturbance to the original parts (in case I need to restore the original setup), and so the original motor has been replaced by an idler shaft driving the original pulley arrangement of the lathe.
The setup seems to have adequate power for this lathe from about 25Hz to 100Hz (lathe rigidity seeming to be the limiting factor with metal removal rate). This gives a speed range in the outer high speed pulley position of 350 RPM to 1400 RPM, and in the low speed outer pulley position of 70 RPM to 280 RPM.
The transformer and VSD should have enough capacity to upgrade the motor to about 1.5kW
The larger motor would give better overlap of high/low speed ranges, but presently I can use the other 4 pulley positions if needed.
The new drive runs much more smoothly and a bit quieter at all speeds than the original drive setup.
Some picture attached showing the setup, rough electrical schematic, and the temporary belt tensioner...
Andrew.
DSCN1286.jpg
DSCN1283.jpg
DSCN1282.jpg
DSCN1280.jpg
DSCN1279.jpg
DSCN1278.jpg
DSCN1276.jpg
DSCN1275.jpg
DSCN1274.jpg
DSCN1273.jpg
DSCN1284.jpg
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