Progress drill motor

I have just brought a Progress number 2G drill that was sold as 3 phase. The specification plate on the motor is very hard to read , but I can just make out some of the details . It has the voltage marked out as 390/415 and 220/240 .

Does this mean it can be changed to single phase or is there such a thing as 240 volt 3 phase.

Cheers Mike

I would suggest that what it means, is that from the factory it has been wired in Star formation to run off conventional 3 phase mains.

It can however be readily altered to Delta formation to run off 220/240 volt three phase mains..

This means that you could change to Delta and run it off an inverter, or lash up something yourself with run and start capacitors to trick it into thinking it's running off 3 phase.

There's likely to be 6 terminals under the cable cover with wires you need to move around.

390 / 415 volts is star (Y) connection. Normal for UK 3 phase utility supply. 220 / 240 volts is delta connection, really handy these days if you want to use a VFD box to convert to single phase.

On a drill the very basic capacitor trick single phase conversion of a delta connected motor works well enough. One capacitor permanently in circuit across one winding and another switched in in parallel across it to get things running. Easy way is to arrange the wiring so the start button connects the extra capacitor whilst depressed so you only have to hold it down for a second or so whilst the motor runs up. Needs to have heft contacts on the button tho'. My Corona 100A had Pollards own interpretation of start button engineering. Mildly crude but monster on the contact side.

The capacitor trick used to be the cheap way to get a three phase motor going on single phase. These days a basic VFD for motors under 1 HP is probably not much more expensive than buying all new components for the capacitor trick. Especially if first or second estimates as to run capacitor size are wrong and you need to get another. There are books giving typical sizes of run capacitor for different size motors but its not an exact science so adjustment to suit your motor is often needed.

Clive

Edited By Clive Foster on 01/06/2016 13:11:03

The last MEW had an article dealing with experimenting with different sized capacitors to get optimal running, if you don't want to buy a VFD and are confident and safe working with mains voltages, it may be worth taking a look.

Neil

Reconnect the motor into Delta, often by moving the brass links. Being dual voltage your motor will have 6 terminals, one group of 3 will be linked together, move those links so that they will each link each row front to rear not along. All that is often on a label within the terminal box. Then you will need several MOTOR RUN capacitors if you are to run the motor that way. Obtain two contactors each fitted with a 240 volt operating coil and a bunch of old fluorescent light fitting capacitors. You need two groups of capacitors each group controlled by its own contactor . One group is the run group the other, which is start group, both are connected in parallel for start up . Once the motor is up and running the start group are disconnected. With a LOT of CARE this is not difficult to achieve and it works well. The down side is getting the current in each phase equal to the next,some careful adjustment is required. I made a sheet steel chassis to fit into a large metal box I already had. I then mounted every thing on the chassis. I had a RED and GREEN pushes mounted on the box. The sequence of operation, press the green button and count 3, both contactor will be energised. On releasing the button the start one drops out and so its capacitors are disconnected, the run one continues to be energised.Motor purrs away.I f you need any more details send me a PM. John

I removed the cover on the motor box but could only see 4 terminals, these are marked U ,V, W, N, plus an earth terminal. In view of this would it be easier to buy a phase converter or a complete new motor.

I recently bought a 2HP single phase to 220V three phase inverter drive for 75 quid delivered from epay. My other two - both 230V single phase to 415V 3 ph @ 0.5 and 1HP - have worked fine. The 415V 3ph. output versions carry a hefty premium over the 220V output versions, so convert to 220V if you decide to go this way! Far better, IMO, as the opportunities for programming soft starts, braked stops, variable speed - and loads more - is worth the outlay.

U, V & W are the 3 phase connections and N is neutral. You generally just use the U, V & W and leave N disconnected. The motor should be fine once you have connected it in delta (so it can use 220V instead of 415V).

A small inverter would run you about £50 or so. The cost depends if you are happy to mess about with capacitors, switches etc, buy an inverter or buy a complete plug and play solution.

Many thanks for replies. Would rather not mess about with capacitors switches , ect. If its a case of just rewiring the motor connections to get 240 v 3 ph instead of 415 v 3 ph that sounds great.,I will give it a go, if someone could explain exactly what wire goes where. And for this I would need a small inverter or something a bit more elaborate,would I. It sounds like a better option than buying a new motor, as mine is large plus there,s the problem of matching the pulley to the new motor shaft.

Mike

Do you have three wires connecting to the neutral terminal? If so then these can be taken off the neutral terminal and connected to the U V and W terminals. You need to use a meter or continuity checker to find the ends of the three windings, U1, V1 and W1. Then connect U1 to V, V1 to W and W1 to U. This sets the motor up for 240v delta. It then is just a case if connecting a suitable vfd or invertor to the U V and W terminals.

Martin

I rewired my three phase milling machine from star to delta and just put a large capacitor across the live and neutral and it ran fine for several years on single phase until I sold it. You only get about 80% of the rated power but that wasn't an issue for me. It didn't like it in the cold weather though in the garage and some days I had to rotate the pulley to start it and then leave it running for a minute or two to warm the motor up. Once warm it would start by itself. Summer was no problem at all though.

Martin

Yes I have three wires connected to the N terminal, I will connect them as you say. Will have to wait till I order the invertor to try it. Will post with results when all is done.

Cheers Mike

I also have a Progress 2G drill press, I bought it almost 20 years ago. They are excellent machines, very rigid and the backgear makes them so usable.

I got rid of the three phase motor and fitted a single phase motor years ago and have always regretted it. So I have bought a new three phase motor and an inverter plus a pendant control and will run the motor on 240 volt three phase via the inverter from the single phase supply. I have already done this on my lathe and mill and what a difference it makes.

The smoother and quieter running, plus variable speed will make the drill even better to use. The programable gentle start up will also be very welcome as these drills sometimes tend to start up with a clunk when in direct drive.

Edited By Lathejack on 01/06/2016 19:06:40

I've got a Progress 2G as well. I robbed the inverter from mine when I got the Bridgeport clone milling machine and replaced the motor with a nasty Chinese single phase travesty. Sounds like a bag of nails and runs as rough as hell. I've now got a decent Yaskawa inverter for the mill so will be able to refit the 3-phase motor. As Lathejack says, the soft start and variable speed make them much friendlier to use.

Mike, if you look at this thread you will see that the same problem was covered, but there was a wiring diagram on the inside of the terminal cover. - **LINK**

May help however

This is all starting to look very easy. Just one more point I thought I should check on. My drill has had a new switch fitted by the previous owner, it is heavy duty with forward-off -reverse. He demonstrated it working on his 415 volt supply when I collected it and it seemed to work very well. It obviously has four wires coming from it and I assume this is simply connected to the inverter. As I am changing my motor from star to delta would I need to make any changes to the switch connections.

Thanks Mike

Just about to order my inverter. My motor is 1 HP so I was thinking of buying a 2 HP converter just to be on the safe side regarding overloading. Is this about right or is it overkill.

Cheers Mike

The one I bought recently is for a one horse power motor and I was told that twice the power is OK (but not much more, if any?)

I think one needs to read the advertising carefully. A one HP motor will clearly require more than 746W at full load. The question of whether a 3/4kW VFD might be at its limit might depend on the integrity of the manufacturer. I would have prefered a 1kW VFD, but I could only find a 1.5kW item at the time at what I thought was a reasonable price. Not seen any at 50 quid like the poster above suggested as what it should cost.

RAB

Mike, the usual way to use an inverter is to connect it directly to the motor. The controls are low voltage and low current connections on the inverter but can be operated by the existing switch in most cases. It just needs wiring up so that there is a connection made for motor run in one position and for motor run and reverse as well in the other. Once you have an inverter and its wiring diagram this should be easy to figure.

Martin

Further to Martins comments as to normal practice being to run the machine via the inverter controls 1 HP units are physically small and it should be possible to mount it on the machine in a position giving direct access to the buttons on the box. If you put it high up there should be no problems with chips getting in and the speed display will be easy to read. Mounting with the dispaly around eye-line would probably be nice.

Makes it easy to change the speed via the inverter if you don't want to fiddle with belts too. In practice ± 1/3 of the nominal motor speed, in round numbers about 900 to 1900 rpm for a 1400 rpm motor, is a good rule of thumb for the generally satisfactory speed range without loosing too much power at the low end or risking problems due to overspeed at the high end. The motor can be run much slower and much faster but for ordinary motors torque drop off rapidly becomes serious outside this range so, at low speeds in particular, power falls off quite dramatically. The inevitable purely mechanical power loss at low speeds due to power = torque x rpm is commonly appreciated but similar torque reduction at high speeds due to rising internally generated back EMF is often overlooked. Probably because high speeds are only used with small components, in this case drills, so not much power is required. Overcoming the back EMF at higher speeds to maintain torque requires a higher voltage from the inverter. All inverters have some over voltage capability as an inevitable consequence of their design but basic, low end, inexpensive inverters have much less overvoltage capability than high specification units. Large overvoltage capability is expensive in the first place and needs more sphisticated innards to get the best out of it.

If you do mount the inverter remotely get proper low level switches to operate it via the external connections. Re-using the high voltage switchgear provided on the machine is frequently unsatisfactory. Partly due to inevitable age and partly because the switches were designed for high voltage not low votage use. I don't like remote mounting of inverters on drills or any other clutchless machinery because of the temptation to twiddle the knob whilst the machine is running and you are away from it. Yup we all know better but at 61 I'm well aware of my own propensity to do really stupid things in the heat of the moment and suspect I'm not unique. With a drill its best to arrange an emergency stop foot button before you put it into service or it won't get done. Mine has been on the roundtoit list for over 10 years!

Probably better for a non electrical / electronics chap to buy a unit complete with "pendant' box having appropriate buttons. There are various reliable suppliers. For example Newton Tesla have a good reputation for supplying all new good quality inverters with good control gear to Model Engineer / Home Workshop types but this is reflected in the price. If you don't mind a used, but ex industrial quality unit, there are various people supplying pendant & inverter sets at a much more wallet friendly price. For example I've dealt with Gavin Osman, who advertises on Homeworkshop.org, in the past with every satisfaction. A used inverter with pendant deal will come out more expensive than the cheap import inverters on E-Bay at the moment. Significantly under £100 for a new 2HP unit is a stonking deal if they are up to snuff but sourcing your own switches and box for remote mounting will cost more than you'd expect if you have to buy all new.

A properly specified 1 HP inverter will be fine for a 1 HP motor on a drill. All inverters have some overload capability so stalling out won't be a problem. Using an ovesize inverter is risky because inverters, especially inexpensive ones, will simply deliver the power the motor asks for. More sophisticated ones can be a bit more controlled if correctly set up. If the motor starts stalling and demands more power a simple, oversized, inverter is going to do its best to deliver it. Which the motor will happly accept possibly leading to a broken drill, flying parts or worse. All inverters have parameter settings to limit power outputs and change torque charactristics to reduce the chances of that sort of thing but even the best manuals are hard to understand. Many are completely incomprehensible to the layman. No nice numbered power setting knob or similar simplicity inside. All buttons and long menus. No point in paying for a 2 HP inverter if safe operation requires you to turn down the maximum output to 1 HP.

Clive.

Edited By Clive Foster on 02/06/2016 20:25:38

Edited By Clive Foster on 02/06/2016 20:26:49

Edited By Clive Foster on 02/06/2016 20:28:16