[pritch1986]

Hello Everybody

i have been converting a Bridgeport series 2 Mill to work on 240 volt single phase

so far i have gotten everything to work bah 1 thing and it's electrical

the electric motor for the head runs fine tested it directly to the power point but not through the control it has something to do with the contactor switches

when my sparky wired it up we couldn't get the motor to run through the control the control does work it powers the table and the coolant pump etc and before we mucked with the contactors the control worked for the motor (you would hear a thunk noise as the start button is pushed)

possible reasons this is blowing fuses and the like is because it is either

A) wired up wrong
B) Phase sensing in the control
C) Contactor coils need to be modified or adjusted

Anybody replaced a 3 phase motor for a single phase one and had this problem any advice would be greatly appreciated

[mactec54]

pritch1986

Why would you change the 3 ph motor for a single phase motor, the 3 ph motor with a VFD would of been a better deal

[pritch1986]

mactec54

i only had single phase and 32 amps to play with

i had to power a 4 HP motor that would only take 415 volt took it to a shop and couldn't get it re-wound for 240 volt

i have an inverter that took 17-18 amps of single phase and turned it into 7-8 amps 3 phase at 240 volt but not at 415 volt and i was going to run out of amperage to get that i still have the 3 phase motor when i hook up 3 phase it will be going back on but that is about $10k down the track

I did look at the options to Invert but it wasn't going to be economical at this point when i could pick up a motor with the same rpm and having some bearings and shaft installed by a mate who's been machining for bout 20 years plus

the funniest part through learning the machine is that to put the motor on it is very difficult to put it on i figured take the bottom disk and assembly and use 2 car jacks to compress the spring to put the keeper back on the shaft (this was only because i didn't have the screws to compress the spring to the vari disk

[Al_The_Man]

Wiring a single phase motor is very simple, if you are using the same contactors as the three phase, just run the 240v 1ph through two top contacts of the contactor and out of the bottom relative two contacts.
You could also use the same over load if adjusts to a suitable limit.
If the contactor is not picking up, it is in the control side, you will need to find out how the contactor coil is now picked up in the new system.
If it is blowing fuses on start up, look for a possible link across two contacts, especially if it is a reverser originally fitted.
Al.

[pritch1986]

heres a photo

[Al_The_Man]

This appears to show the old original 3ph reverser, is this what you are using presently?
Also the wiring from the disconnect to the contactor appears to be wired for 3ph still?
If the machine was converted to 1ph 240, I would expect that the wiring for one of the phases would have been removed?
If you remove the wires from the bottom of the contactor to prevent the fuse blowing, does the contactor in the centre pull in OK?
Al.

[pritch1986]

that's an old photo i happened to have on my phone for if i want to turn it back to three phase later on. i will be out at my shop later today and i'll take a photo of what the sparky has done and we'll go from there

but one thing i will add is that when it was wired up for 3 phase the Contactors were clicking in with a loud thud on both high and low on a 240 volt supply the transformer has been rewired for 240 volt so thats all good

[pritch1986]

here's some photos of how it is wired atm

[mactec54]

mactec54

i only had single phase and 32 amps to play with

i had to power a 4 HP motor that would only take 415 volt took it to a shop and couldn't get it re-wound for 240 volt

i have an inverter that took 17-18 amps of single phase and turned it into 7-8 amps 3 phase at 240 volt but not at 415 volt and i was going to run out of amperage to get that i still have the 3 phase motor when i hook up 3 phase it will be going back on but that is about $10k down the track

That make sense, strange the motor did not have more than one input voltage

[Al_The_Man]

If you drop the power out of the bottom of the contactor does the contactor armature pull in and does the fuse stay intact?
If so, it is the wiring to the motor.
The wiring colours are a bit confusing, it pays to stick to the approved colour, e.g. white is usually reserved for neutral.
What is the white and red under the L.H. top terminal?
Al.