Deano
11-08-2010, 09:13 PM
thought you guys might be intrested in how i converted my new secondhand 3 phase lathe and mill to single phase.
all electrical work should be done by a licenced electrician, i am not a licenced sparky but all work on my machines was carried out by a licenced electrician.
first of all i started with a mill that i brought from a company down the raod a bit. it is a Ostmac mill KR-V2000 made by king rich. i had this mill inspected by the local King Rich service agent/importer before i purchased it so that i didn't end up buying a worn out hunk of junk.
http://www.asfphotos.com/upload/1281583135.jpg
i was looking for this particular model and brand (KR-V2000) cause i new they had a dual tapping transformer and the transformer would not have to be changed to to power all the accessories like power feed, digital readout, coolant pump and the contactors.
after getting the mill home and giving it a bit of a clean up we got stuck into the conversion.
many hours were spent gazing into the cabnient working out what contactors did what and how the emergeny circuits worked
first of all the 3phase power lead had been removed from the machine and it got replaced with a 240v plug.
at this point you have 3 phases going throught the elect cab. as single phase just has a neutral and a power wire and a common earth only 2 of the 3 wires are used.
then following the power circuits through the fuses using only 2 of the 3 fuses (1 neutral 1 active) are been used, the power from the output of the fuse braches off to power the transformer and power the accessories like coolant pump, dro, powerfeed and contactor. previous the transformer had 2 wires going into it. it has multiple inputs dependant on the voltage. we connected our neutral to the 0volt imput and active to the 240v input.
once this was connected we had power for the accessories and we tested them and they all worked. the dro takes 240v the powerfeed takes 110v and from memory the contactors were 110v as well.
by this stage we had worked out what the 3 contactors did. in the pic the top contactor is the spindle motor, the middle contactor is the powerfeed and bottom contactor is the coolant pump.
http://www.asfphotos.com/upload/1281579034.jpg
nowing now that the powerfeed is a goer cause it gets it 110v from the transformer its circuits remain untouched.
the original coolant pump was 3 phase so i swapped that for a single phase unit. the coolant pump got its power from the output of the fuses. so i knew we didn't have to change anything there except disconnect the unused wire from the 3ph system.
the spindle motor is a 3hp motor that is a special king rich motor that cant be connect in delta (220v 3phase) without mods. to use this 220v 3ph from an inverter you need to use the delta windings. because this motor was only designed for running on 415v 3ph the delta windings were still attached to the main windings. i pulled the motor a part and took it to a motor rewinder. they picked out the wires and extended them to the terminal box. the pic shows the original black wires and the new red wires.
http://www.asfphotos.com/upload/1281565781.jpg
once this mod was done the motor will then run on 220v 3phase. i brought an invertor to take care of the 240v single phase to 220v 3phase conversion.
the invertor gets its power from the master switch so when switched on the master switch feeds power to the electrical cab and the inverter.
the original forward reverse duties were taken care of by a rotary switch that would just reverse 2 phases to reverse the motor direction. this would not be suitable in this conversion.
i removed this siwtch completely.
the inverter is a good piece of kit and it requires a forward / reverse input. it has a common 24v output and depending on what terminal you return the 24v to determines if the motor starts in reverse or forward. i replaced the pilot light on the mill control panel with a 3 position rotary switch that became my new forward/reverse. so in the middle was off, turn to the left for forward turn to the right for reverse.
because this machine has a e stop we had to work out how to incorperate this into the conversion. in the end we removed the old power wires that the spindle contactor switched and replaced them with just the 24v feed wire that goes to the forward reverse switch so when you hit the e stop all 3 contactor release and this means the 24v signal to the invertor is cut and the invertor thinks you have just turned the switch off.
the good thing about using the invertor for the forward and reverse is you can program the ramp up and ramp down when you turn the motor on and off. takes a bit off shock out of the drive. i set the ramp up to 1second and the ramp down to 0 (coast to a stop)
so that is about all you need to no about this conversion. a bit of programming in the inverter but nothing more confusing than programming a new tv.
i also brought a box for it to live in and bolted it to the back of the mill. the box is empty cause the invertor was on the lathe when i took the pic but you get the idea.
http://www.asfphotos.com/upload/1281582597.jpg
all electrical work should be done by a licenced electrician, i am not a licenced sparky but all work on my machines was carried out by a licenced electrician.
first of all i started with a mill that i brought from a company down the raod a bit. it is a Ostmac mill KR-V2000 made by king rich. i had this mill inspected by the local King Rich service agent/importer before i purchased it so that i didn't end up buying a worn out hunk of junk.
http://www.asfphotos.com/upload/1281583135.jpg
i was looking for this particular model and brand (KR-V2000) cause i new they had a dual tapping transformer and the transformer would not have to be changed to to power all the accessories like power feed, digital readout, coolant pump and the contactors.
after getting the mill home and giving it a bit of a clean up we got stuck into the conversion.
many hours were spent gazing into the cabnient working out what contactors did what and how the emergeny circuits worked
first of all the 3phase power lead had been removed from the machine and it got replaced with a 240v plug.
at this point you have 3 phases going throught the elect cab. as single phase just has a neutral and a power wire and a common earth only 2 of the 3 wires are used.
then following the power circuits through the fuses using only 2 of the 3 fuses (1 neutral 1 active) are been used, the power from the output of the fuse braches off to power the transformer and power the accessories like coolant pump, dro, powerfeed and contactor. previous the transformer had 2 wires going into it. it has multiple inputs dependant on the voltage. we connected our neutral to the 0volt imput and active to the 240v input.
once this was connected we had power for the accessories and we tested them and they all worked. the dro takes 240v the powerfeed takes 110v and from memory the contactors were 110v as well.
by this stage we had worked out what the 3 contactors did. in the pic the top contactor is the spindle motor, the middle contactor is the powerfeed and bottom contactor is the coolant pump.
http://www.asfphotos.com/upload/1281579034.jpg
nowing now that the powerfeed is a goer cause it gets it 110v from the transformer its circuits remain untouched.
the original coolant pump was 3 phase so i swapped that for a single phase unit. the coolant pump got its power from the output of the fuses. so i knew we didn't have to change anything there except disconnect the unused wire from the 3ph system.
the spindle motor is a 3hp motor that is a special king rich motor that cant be connect in delta (220v 3phase) without mods. to use this 220v 3ph from an inverter you need to use the delta windings. because this motor was only designed for running on 415v 3ph the delta windings were still attached to the main windings. i pulled the motor a part and took it to a motor rewinder. they picked out the wires and extended them to the terminal box. the pic shows the original black wires and the new red wires.
http://www.asfphotos.com/upload/1281565781.jpg
once this mod was done the motor will then run on 220v 3phase. i brought an invertor to take care of the 240v single phase to 220v 3phase conversion.
the invertor gets its power from the master switch so when switched on the master switch feeds power to the electrical cab and the inverter.
the original forward reverse duties were taken care of by a rotary switch that would just reverse 2 phases to reverse the motor direction. this would not be suitable in this conversion.
i removed this siwtch completely.
the inverter is a good piece of kit and it requires a forward / reverse input. it has a common 24v output and depending on what terminal you return the 24v to determines if the motor starts in reverse or forward. i replaced the pilot light on the mill control panel with a 3 position rotary switch that became my new forward/reverse. so in the middle was off, turn to the left for forward turn to the right for reverse.
because this machine has a e stop we had to work out how to incorperate this into the conversion. in the end we removed the old power wires that the spindle contactor switched and replaced them with just the 24v feed wire that goes to the forward reverse switch so when you hit the e stop all 3 contactor release and this means the 24v signal to the invertor is cut and the invertor thinks you have just turned the switch off.
the good thing about using the invertor for the forward and reverse is you can program the ramp up and ramp down when you turn the motor on and off. takes a bit off shock out of the drive. i set the ramp up to 1second and the ramp down to 0 (coast to a stop)
so that is about all you need to no about this conversion. a bit of programming in the inverter but nothing more confusing than programming a new tv.
i also brought a box for it to live in and bolted it to the back of the mill. the box is empty cause the invertor was on the lathe when i took the pic but you get the idea.
http://www.asfphotos.com/upload/1281582597.jpg