James
Almost any of the well known makes of inverter (correctly called 240v 1-Phase to 240v 3-Phase Variable Frequency Devices) rated at 0.75kW or more would be ok. It really depends on your skill in "Electricals" as to which you buy.
There's a guy who advertises regularly in "homeworkshop.org.uk" at less than retail and he will provide assistance. I bought my latest unit and motor a lot cheaper from e-bay. After collecting a number of manufacturer's data sheets, user manuals, etc, I was able to "tell exactly what was on offer" - more than could be said for many of the sellers !
For example, Mitsubishi make an inverter which has an inbuilt potentiometer for speed control. They also make a similar unit without this "pot". Both can be controlled by "up/down" buttons if required - not very "user friendly" - IMHO - but "usable" at a pinch.
You will find that other manufacturers, eg IMO supply similar variants in their range.
A word - or two - on Control Panels
Most units can be made to work "out of the box", however, for best results and to acheive the performance you want (eg DC injection braking vs Coasting to stop, Min/Max speed setting, internal/external control option, etc) you will need to change some "parameters" in the unit. This requires the appropriate control panel or an alternative PC/S'ware hook-up.
Some VFDs are supplied, as standard, with only very simple control or monitoring panels - usually only with start & stop buttons and a couple of status LEDs. Sometimes, they only have the LEDs.
Although some VFDs can be used “as so fitted” and others may only require external switches and a potentiometer to run, there is no provision for changing parameters or displaying the output frequency. More sophisticated control panels can be obtained and fitted as optional extras at a cost of ~£25.00 + VAT.
The Siemens Micromaster 420 series VFDs and Mitsubishi FR-E520S series VFDs are supplied with very simple panels and would benefit from the fitting of their optional panels.
The IMO Jaguar Cub series, SDD 601, 605 & 650 series and the Mitsubishi FR-S520S series of VFDs are fitted with adequate panels as standard.
It is worth checking, when buying, if a Programming, Monitoring & Control Panel is supplied with the unit.
Manufacturers & Suppliers of VFDs
There are (were) many manufacturers and this is, by no means, a full listing. Some of these devices are - or were - also “OEM Badged” for motor manufacturers - for example Brush and Brook-Hansen.
In alphabetical order:-
Emotron, Hitachi, IMO, Lenze, Mitsubishi, Omron, SDD, SEW, SIEI, Siemens, TECO, Telemechanique and Vectron.
Of these my personal favourites would be the IMO Jaguar Cub series or the Mitsubishi FR-S520S series. Principally because they are supplied with a full control panel and have an inbuilt speed adjustment “knob” and are, therefore, best suited to "our" applications.
Next in line, I would recommend the SDD (pka Eurotherm) 601, 650 series.
The Siemens Micromaster 420 + Basic Operators Panel (BOP) or Mitsubishi FR-E520S + FR-PA02-02 Control Panel come a close third.
One word of warning regarding RCDs and EME
Some VFDs have shown a tendency to trip RCDs in domestic properties. They obviously wouldn't do this in industrial situations - otherwise they wouldn't sell any. A Siemens 420 unit showed this tendency on a friend's installation and I noted that additional, optional input filtering was available to cure this. I have fitted a 1.5kW (2hp) Mitsubishi unit in my lathe
and bought my milling M/C with a Eurotherm 1.1kW (1.5hp) unit already fitted. Neither exhibit any problems in this regard.
Also, it's worth checking if an external EME filter is required. Due to the high-frequencies at high-power supplied to the motor an EME filter is necessary as is a screened cable from the unit to the motor. Many units (eg Mitsubushi) are fitted internally with EME filters as standard, some require an internal filter to be specified (ie it's a suffix on the part number) ar extra cost and some require an additional, external - optional extra - EME filter.
Finally
Check that the Input voltage is 240v Single-phase and output is 240v 3-phase. Most Manufacturers make both "240v 1-Phase input" and "414v 3-phase input" units with very similar part-numbers. Some also make (or made) units with 240v/1 in and 415v/3 out. These can sometimes appear on e-bay.
If you want to discuss oprions further, send me a PM.
Prices
Retail Price (April 2006) of a 1.5kW unit varied from £206 inc VAT for a Mitsubishi FR-S520 from Newton-Tesla to £411.00 inc VAT for an SDD 605 from RS.
As previously noted, optional control panels - where needed - were circa £25.00 and EME filters (to stop interference to your neighbours' TVs, etc), if not internal, are circa £27.00 inc VAT.
On E-Bay, the same size units have been sold for £90.00 to £120.00 as “Buy-now” or achieved auction bids of £60.00 to £90.00. (I paid £85.00 for mine)
As I said, units have been advertised on
www.homeworkshop.org.uk - by a “Model Engineer” who claims he isn’t a dealer - in the £150.00 to £160.00 range.
Delivery charges can by up to £15.00 extra from manyt of these sources.
If you are searching on E-Bay for VFDs, you may find them described as Converters or Inverters. I’d suggest that you use both words, independently, for your searches. Many vendors don’t know the difference and use the words interchangeably. You might miss a bargain otherwise.
BTW. The above is offered in an attempt to assist fellow Model Engineers and is not intended - nor should it be regarded - as Professional Advice nor a recommended design of any sort.
. I havent yet taken the motor out to gain access to the terminal box but would imagine im not going to see any link bars inside. My question is, can i just wire the boxford motor to the inverter regardless of how the windings are connected? 
. I havent yet taken the motor out to gain access to the terminal box but would imagine im not going to see any link bars inside. My question is, can i just wire the boxford motor to the inverter regardless of how the windings are connected? 
