24-05-2012, 10:58 AM
Hi,
Thanks Big Al, if you connect a 3 phase 415V motor from Star to Delta and use a start and run capacitor to power from 240V the motor doesn't run at full power but enough power for most duties.
About 12 years ago I did this with my big Startrite Combination 5 function woodworking machine. As this machine is fitted with three similar 3 phase 415V motors I re-connected all the motors from Star to Delta with a bit of fancy wiring so that selecting each function through the main rotary switch only a single start and single run capacitor was required. The machine is started by pushing two buttons; one is the normal run button but the other button brings the start capacitor online and once the machine runs up to speed both buttons are released; the run circuit remains online but the start capacitor drops offline; I found this to be the simplest way for me but I know other methods are available. The machine is fitted with two stop buttons for safety.
Not all 415V 3 phase motors can be connected in Delta because the old type motors have their Star connection buried deep in the windings and it's possible to destroy the motor whilst trying to dig the Star connections out. A more modern 3 phase 415V motor will usually have a "T" box (Terminal box) attached to the motor body and this houses the connections; there will be six wires from the windings and three copper straps will be seen; these straps make changing from Star to Delta very easy and also usually there is a circuit diagram stuck to the inside of the lid.
The Startrite will only "cut out" if heavy sawing is attempted as the overload trips but for general use the machine is fine and it gets a lot of use. I could phase balance it to the 3 phase 415V transformer but as it works so well why bother. The biggest problem with this conversion is in trying to obtain the correct capacitor ratings. The start capacitor can be oversize as it is in circuit for only seconds but when I first started doing such a conversion I've had a run capacitor explode which is an attention grabber.
Back on topic and I'm pleased to add the reply about the oil from Doug at "Unique3phase". I knew Doug would respond quickly and I've just thanked him; here is the reply in full and I am unable to expand on the information because I have no knowledge of oil cooling a transformer;
Hi Colin, Thanks for all the plugs you put in for me. I think it helps boost sales as everyonce in a while there are a bunch of people that buy and then it slacks off for a while.
"I used the Dextron transmission fluid because I found some one on the web that was an amateur radio operator that had investigated it for use in a oil cooled dummy load. He stated that the fluid was recommended for use in the hydraulic units on line service trucks. As in power line high voltage repair. I don't know if that was a marketing ploy by the makers of Dextron or not but it has a high flash point. I found it in 5 gallon pails at a tractor supply store so it was a lot cheaper then buying it in quarts or liters. Doug"
I hope this is of use Ed but at least it is something to think about and will possibly save you a lot of money.
Kind regards, Col.
Thanks Big Al, if you connect a 3 phase 415V motor from Star to Delta and use a start and run capacitor to power from 240V the motor doesn't run at full power but enough power for most duties.
About 12 years ago I did this with my big Startrite Combination 5 function woodworking machine. As this machine is fitted with three similar 3 phase 415V motors I re-connected all the motors from Star to Delta with a bit of fancy wiring so that selecting each function through the main rotary switch only a single start and single run capacitor was required. The machine is started by pushing two buttons; one is the normal run button but the other button brings the start capacitor online and once the machine runs up to speed both buttons are released; the run circuit remains online but the start capacitor drops offline; I found this to be the simplest way for me but I know other methods are available. The machine is fitted with two stop buttons for safety.
Not all 415V 3 phase motors can be connected in Delta because the old type motors have their Star connection buried deep in the windings and it's possible to destroy the motor whilst trying to dig the Star connections out. A more modern 3 phase 415V motor will usually have a "T" box (Terminal box) attached to the motor body and this houses the connections; there will be six wires from the windings and three copper straps will be seen; these straps make changing from Star to Delta very easy and also usually there is a circuit diagram stuck to the inside of the lid.
The Startrite will only "cut out" if heavy sawing is attempted as the overload trips but for general use the machine is fine and it gets a lot of use. I could phase balance it to the 3 phase 415V transformer but as it works so well why bother. The biggest problem with this conversion is in trying to obtain the correct capacitor ratings. The start capacitor can be oversize as it is in circuit for only seconds but when I first started doing such a conversion I've had a run capacitor explode which is an attention grabber.
Back on topic and I'm pleased to add the reply about the oil from Doug at "Unique3phase". I knew Doug would respond quickly and I've just thanked him; here is the reply in full and I am unable to expand on the information because I have no knowledge of oil cooling a transformer;
Hi Colin, Thanks for all the plugs you put in for me. I think it helps boost sales as everyonce in a while there are a bunch of people that buy and then it slacks off for a while.
"I used the Dextron transmission fluid because I found some one on the web that was an amateur radio operator that had investigated it for use in a oil cooled dummy load. He stated that the fluid was recommended for use in the hydraulic units on line service trucks. As in power line high voltage repair. I don't know if that was a marketing ploy by the makers of Dextron or not but it has a high flash point. I found it in 5 gallon pails at a tractor supply store so it was a lot cheaper then buying it in quarts or liters. Doug"
I hope this is of use Ed but at least it is something to think about and will possibly save you a lot of money.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
