- Thread starter s410man
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Yes you will need a very expensive inverter to power a dual speed motor as it will have to be a true 440v three phase output if you want to maintain the dual speeds.
I've got a 3hp motor in my colchester and powered it up with an Variable Frequency Drive or inverter for less than £250 so nowhere near a grand.
My mill came with a dual speed motor which is not inverter compatible (without great expense) so i binned that motor and got a simple 2hp three phase for £40.
The capabilities of modern VFD inverters far outweight the ancient technology employed on most of these old industrial machines. No need for a twin speed motor when you've got infinitely variable speed from an inverter drive.
The advantages an inverter drive gives I would recommend one every time rather than swapping to a single phase motor.
Bet thats wired direct to the motor doing away with all the controls and coolant.
A 5.5hp plug and play inverter lasted 1 1/2 hrs £650 thank you, good bye. The startup current is equivalent to starting a 9hp motor!
Soft start has no function just delays the relays and contacts tripping in, once tripped in its full hard start.
I have a 4KW rotary convertor as back up, put a cut on spindle slows and judders with a 3hp motor. Ok for pissy cuts 2mm.
A 5.5hp plug and play inverter lasted 1 1/2 hrs £650 thank you, good bye. The startup current is equivalent to starting a 9hp motor!
Soft start has no function just delays the relays and contacts tripping in, once tripped in its full hard start.
I have a 4KW rotary convertor as back up, put a cut on spindle slows and judders with a 3hp motor. Ok for pissy cuts 2mm.
You could change to a single phase motor quite easily.
Don't let Hareng's bad experience put you off inverter technology. The cost isn't as high as he says and the advantages make it well worth it. As well as the near infinite speed control you get motor thermal and over current protection, soft start and variable motor braking, jog functions amongst others, a decent inverter drive also preserves the full power of the motor not like the artificial three phase of a rotary converter.
I run the coolant motor off my inverter with no problems also. I also use the same inverter to power my milling machine or pillar drill, just not all at the same time.
You could chance your arm with an inverter as cheap as this:-
http://www.ebay.co.uk/itm/VARIABLE-FREQUENCY-DRIVE-INVERTER-VFD-3HP-2-2KW-10A-e6-/120674103836?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1c18bcb21c
or spend a little bit more and get one from a reputable british company:-
http://stores.ebay.co.uk/Drives-Direct-Inverters-LTD?_trksid=p4340.l2563
The less expensive inverters like mine require to be hard wired to the motor, bypassing all machine switches contactors etc. You then re-wire the switches emergency stops to act on the low voltage controls to the inverter. Not too difficult if you know what you are doing and drives direct will give you guidance.
Don't let Hareng's bad experience put you off inverter technology. The cost isn't as high as he says and the advantages make it well worth it. As well as the near infinite speed control you get motor thermal and over current protection, soft start and variable motor braking, jog functions amongst others, a decent inverter drive also preserves the full power of the motor not like the artificial three phase of a rotary converter.
I run the coolant motor off my inverter with no problems also. I also use the same inverter to power my milling machine or pillar drill, just not all at the same time.
You could chance your arm with an inverter as cheap as this:-
http://www.ebay.co.uk/itm/VARIABLE-FREQUENCY-DRIVE-INVERTER-VFD-3HP-2-2KW-10A-e6-/120674103836?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1c18bcb21c
or spend a little bit more and get one from a reputable british company:-
http://stores.ebay.co.uk/Drives-Direct-Inverters-LTD?_trksid=p4340.l2563
The less expensive inverters like mine require to be hard wired to the motor, bypassing all machine switches contactors etc. You then re-wire the switches emergency stops to act on the low voltage controls to the inverter. Not too difficult if you know what you are doing and drives direct will give you guidance.
Have a butchers £375
http://www.drivesdirect.co.uk/Products/Motor_Inverter_Packages.htm
Remote pod as an extra, heres the wiring for that.
http://www.drivesdirect.co.uk/Image...N-DIAGRAM-WITH-START-STOP-FWD-REV-+-SPEED.jpg
If its the older one with a clutch, youve got it made easy on go with link at top similar to Stormin.
Motors permanently running once powered up, cluch operates the spindle, far better than new stuff.
If its newer like these and Harrisons.
http://www.lathes.co.uk/colchester/page18.html
http://www.lathes.co.uk/colchester/page19.html
As in first link but will need to junk the control panel and lathe functions.
I would ask Dave if that invertor can be wired to operate stop start from lever control micro switches = 7 wires. Sure it can but would have to figure the two micro switches out.
You will loose all existing lathe functions, emergency stops, foot brake, spindle stop/start, lighting etc. plus the coolant unless you can live with variable dependant upon the motor speed.
http://www.drivesdirect.co.uk/Products/Motor_Inverter_Packages.htm
Remote pod as an extra, heres the wiring for that.
http://www.drivesdirect.co.uk/Image...N-DIAGRAM-WITH-START-STOP-FWD-REV-+-SPEED.jpg
If its the older one with a clutch, youve got it made easy on go with link at top similar to Stormin.
Motors permanently running once powered up, cluch operates the spindle, far better than new stuff.
If its newer like these and Harrisons.
http://www.lathes.co.uk/colchester/page18.html
http://www.lathes.co.uk/colchester/page19.html
As in first link but will need to junk the control panel and lathe functions.
I would ask Dave if that invertor can be wired to operate stop start from lever control micro switches = 7 wires. Sure it can but would have to figure the two micro switches out.
You will loose all existing lathe functions, emergency stops, foot brake, spindle stop/start, lighting etc. plus the coolant unless you can live with variable dependant upon the motor speed.
How on earth do you run 3ph coolant pump at a steady pace?
As far as i am aware the voltage varies dependant upon the pot setting. Meaning if spindle speed is altered you would constantly keep having to alter the flow.
My coolants dual voltage but 3ph 3HP motor is not.
Originally took a flyer on Stormins inverter it just puts out 220V no good like me having a non dual voltage motor. Look far easier to configure and wire than MA7200
Manuals useless 100 odd pages blinding you with science.Would have been far cheaper to buy new motor.
I was mis sold the second time by above name having to lash out on an MA7200 plug and play 4KW. All i was told was to wire direct to motor and figure out the wiring for myself after many months.
Why do you have to lose all existing lathe functions? No reason all the simple switches cannot be linked to the inverter controls, usually taking one set off connections off the existing contactor and bypassing it via the inverter.
My coolant pump still runs well even when I have the VFD down to 5 hz, you just open the tap up a bit more on the feed, but at those slow speeds you don't really need coolant, ultra slow speed is only really used when threading to a shoulder or touching off to fix a depth or centreing.
I will admit to having fed the work light off a seperate supply on my milling machine but only so I could but a low voltage 12v transformer in there for safety. Didn't much fancy a 240v light getting splashed by coolant.
How on earth do you run 3ph coolant pump at a steady pace?
As far as i am aware the voltage varies dependant upon the pot setting. Meaning if spindle speed is altered you would constantly keep having to alter the flow.
My coolants dual voltage but 3ph 3HP motor is not.
Originally took a flyer on Stormins inverter it just puts out 220V no good like me having a non dual voltage motor. Look far easier to configure and wire than MA7200
Would have been far cheaper to buy new motor.
I was mis sold the second time by above name having to lash out on an MA7200 plug and play 4KW. All i was told was to wire direct to motor and figure out the wiring for myself after many months.
I admit that I don't have a `pot' to alter the motor speed so just set it before the start of a job and set coolant flow to suit as the turning or milling starts. Why would you really want to alter the speed during a cut? Even so if you can turn a dial on a pot you can turn a tap on a coolant pipe.
Not having a dual voltage motor doesn't have to be the end of using a cheap inverter. I changed the main motor on my mill because it was dual speed, effectively two motors in one with a complicated set of windings, it was easier and cheaper to get a dual voltage 2 hp motor.
The second motor in the mill ran the coolant pump and the power feeds to the head. This was also a single voltage motor wired for star (440v), a quick visit to my motor rewinds man and £20 later he had found the star point of the motor, re-soldered a few wires and the motor was now fixed in Delta and suitable for 240V three phase. Having watched him do the job it was so simple that I'd have a go myself next time I have the problem.
So which motor have you got in at the moment the single speed 3 hp or twin speed 2.5 / 5 hp?
By putting in a 3hp motor you wouldn't be downrating the machine, the 5hp motor uses the extra power to spin faster, powering two sets of windings.
Single phase motors do not last as long as three phase motors and don't like stop start actions, soon ruins the capacitors. The also don't give as good a finish to the machined face as they don't run as smoothly.
its on a lathe i am buying so i dont know as i havent got it here to look at
when i asked him he said about 4 hp so i dont know which one it is
ill have a look tomorrow
thanks
ronan
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How much would the performance be down if i swapped out the 5hp motor for a 3hp one and ran it off a vfd ? The lathe is a colchester master 2500 , i have no need for huge cuts or massive speeds really.
penfold
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The suds pump doesn't need variable speed, so just wire it separately via a simple static converter made with capacitors and a relay.
As for exploding/dying VFDs, whoever advised you was a bandit and seems to have given you no useful help at all; VFDs should be wired directly to the motor, never through a contactor or any other legacy switchgear. Wiring a VFD with switchgear between it and the motor is madness.
Safety cutouts and other items should be linked to the VFD only via the low voltage control interface. It's often a bit of work doing it, but the results are worth it; my Viceroy is a delight to use with it. A 2mm cut is fairly big for 3hp, if you want heavy cutting capacity you will need a bigger motor and pay accordingly. I don't see the point on a hobby machine.
As for exploding/dying VFDs, whoever advised you was a bandit and seems to have given you no useful help at all; VFDs should be wired directly to the motor, never through a contactor or any other legacy switchgear. Wiring a VFD with switchgear between it and the motor is madness.
Safety cutouts and other items should be linked to the VFD only via the low voltage control interface. It's often a bit of work doing it, but the results are worth it; my Viceroy is a delight to use with it. A 2mm cut is fairly big for 3hp, if you want heavy cutting capacity you will need a bigger motor and pay accordingly. I don't see the point on a hobby machine.
The reason I was suggesting performance wouldn't really be down on the Harrison is that it is set-up as a twin speed motor. Assuming the 5hp motor in your Master is single speed then going to a 3hp would cut the power down to 60% of the original give or take a little for transmission losses. Shouldn't be too much of an issue if you really do only intend to take light cuts and not push it. Also bear in mind the weight of material in the chuck and it's inertia. A large motor is needed to start a large peice turning from standstill regardless of cutting force. A VFD will help in this respect due to the programmeable soft start feature. It may take a while to get upto speed however.
Why remove the 5hp motor anyway? It's probably cheaper to buy a 5hp rated inverter unless you already have a 3hp motor kicking around doing nothing.
Ronan, think you will be hard pushed to find a 220V output VFD that would cover 5hp motor, most stop at 3hp to run maybe a 2hp motor with soft start.
Direct Drives do them with 220V output.
Masters, Mastiffs, Students all have same cross slides as Harrison. Personally i would drop down to a new 3hp motor and inverter package from some where reputable.
Direct Drives do them with 220V output.
Masters, Mastiffs, Students all have same cross slides as Harrison. Personally i would drop down to a new 3hp motor and inverter package from some where reputable.
Valid point but i will tell you straight up my old Harrison 140 single phase 1 1/2HP 240V you could thin down 2" dia round to 1" round in one pass on power feed with hardly any murmer!
Heres an action still 1/2" facing cut on 5" dia aluminium 6082.
http://pic20.picturetrail.com/VOL15/728921/1252422/14582043.jpg
Its a proper geared head with British decent motor.
Different lathe another Harrison with VFD 4KW wired direct to 3hp 3ph 400V motor couldnt put 2mm on without serious issues.
A 400V 3ph 4KW MA7200 inverter £650 could get away with 3mm but was moaning.
7.5KW MA7200 inverter same 3hp machine, can take but struggles with 3/8" cut as long as the tips being used. Thats reducing dia 3/4".
