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.

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

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.

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'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.

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

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