bhk
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Post by bhk on Sept 20, 2014 21:56:06 GMT
To my knowledge a step up inverter doesn't exist. An inverter works by first rectifying the mains to 230v DC then chopping it about to vary the frequency and on time vs off time(PWM) You could stick a 3 phase step up transformer after the inverter but it would cost several times that of a new motor They most defiantly do www.drivesdirect.co.uk/Products/Digital_Inverters240_415.htm
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bhk
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Post by bhk on Sept 20, 2014 22:05:12 GMT
I have to confess that I haven't come across any step up VFDs so I don't really know what they look like. I imagine there's a pretty chunky inductor on the front end of the drive to step up the voltage. I'm sure you'll check the specification and make sure it's suitable. I don't think there's any problem with those Chinese drives, the ones I've come across seem to work ok although I haven't bought them myself. The seller is sketchy with his details but at the current price I would happily buy just to rip it apart and see how it works , like I said if I get it at the current price it's worth a punt. I have been in touch with Direct Drives regards the units linked in my previous post and they are proving very helpful, this would most likely work out cheaper than a new motor and VFD combo as postage would be less.
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Post by Roger on Sept 20, 2014 22:51:13 GMT
That looks like quite a beast! I think they're keeping the size of the inductor/transformer down by chopping it at a high frequency in much the same way they produce switched mode power supplies. It's a well proven method but I've not seen it on this sort of application before. That's very interesting. My guess is that they rectify the input first to an intermediate DC voltage bus and then up convert it to a higher voltage for the output stages.
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jma1009
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Post by jma1009 on Sept 20, 2014 23:01:12 GMT
hi sean, i had a friend who had a very similar sized lathe to yours (albeit a large Boxford) with a single phase motor fitted and did everything you could possible want for the model engineer. if the lathe has a gearbox who not use it! that's what it is there for! your colchester looks a lovely lathe and reminds me of metric colchesters i used as a teenager (cursing coz i was converting to imperial all the time!) and the time i took the top off my knuckle on one on the toolpost and being rushed to hospital! cheers, julian
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steam4ian
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One good turn deserves another
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Post by steam4ian on Sept 21, 2014 4:55:41 GMT
Sean If you follow Julian's advice firstly you will need to find a single phase motor which will fit in the space. If you are so lucky you will find that it has less HP than what it replaces. When choosing a single phase motor make sure it is Capacitor start, capacitor run so that you have the starting torque, this is important, unfortunately it will make the motor outline larger due to the two capacitors. Whilst I have not seem a "step up" VSD (surprising considering my extensive industry exposure) I am sure they could exist. A step up transformer is unnecessary. The required dc bus voltage, somewhat more than 700 volts, can be obtained by a full wave voltage doubling rectifier instead of the usual bridge rectifier. The voltage doubler will need two capacitors of twice the capacity of a bridge rectifier solution; the usual Pulse Width Modulated system inverter will follow. If importing such an inverter you may need to consider getting a permit to actually connect it in Oz/NZ. Take the details of what you have found and see if a local (to you) importer can get it for you. Try Royce Cross agencies or similar. I attach a link to Zener drives www.zener.com.au/images/Technote_VSD_on_Single_Phase_Supplies.pdf , not necessarily helpful because they suggest an input transformer 240/415 volts. Keep in touch Regards Ian
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bhk
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Post by bhk on Sept 21, 2014 8:04:25 GMT
hi sean, i had a friend who had a very similar sized lathe to yours (albeit a large Boxford) with a single phase motor fitted and did everything you could possible want for the model engineer. if the lathe has a gearbox who not use it! that's what it is there for! your colchester looks a lovely lathe and reminds me of metric colchesters i used as a teenager (cursing coz i was converting to imperial all the time!) and the time i took the top off my knuckle on one on the toolpost and being rushed to hospital! cheers, julian Hi Julian, I have no doubt that fitting a single phase motor would be more than ample for me. But I've waited 3 years to find the right machine so I'm going to make sure I get the best powering option. If I can get a VFD for a little more than a single phase setup I'll do it, but if I can get a DRO and a single phase motor for the same price then I'll go that direction. I found the serial number the other day and the machine was built 1967 I can't believe its lasted the years as well as it has! Cheers Sean
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bhk
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Post by bhk on Sept 21, 2014 8:31:36 GMT
Sean If you follow Julian's advice firstly you will need to find a single phase motor which will fit in the space. If you are so lucky you will find that it has less HP than what it replaces. When choosing a single phase motor make sure it is Capacitor start, capacitor run so that you have the starting torque, this is important, unfortunately it will make the motor outline larger due to the two capacitors. Whilst I have not seem a "step up" VSD (surprising considering my extensive industry exposure) I am sure they could exist. A step up transformer is unnecessary. The required dc bus voltage, somewhat more than 700 volts, can be obtained by a full wave voltage doubling rectifier instead of the usual bridge rectifier. The voltage doubler will need two capacitors of twice the capacity of a bridge rectifier solution; the usual Pulse Width Modulated system inverter will follow. If importing such an inverter you may need to consider getting a permit to actually connect it in Oz/NZ. Take the details of what you have found and see if a local (to you) importer can get it for you. Try Royce Cross agencies or similar. I attach a link to Zener drives www.zener.com.au/images/Technote_VSD_on_Single_Phase_Supplies.pdf , not necessarily helpful because they suggest an input transformer 240/415 volts. Keep in touch Regards Ian Hi Ian, I believe I've sailed with some HV system 3.3kv and upwards that use the same theory on drives to reduce transmission losses on the DC bus bar. I can isolate the systems and do the mechanical maintenance on these drives but the electronics shy of understanding the principals is white man magic to me! Cheers Sean
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uuu
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Post by uuu on Sept 21, 2014 10:26:28 GMT
If you do decide to go single-phase, you might like to choose a 2800rpm motor, to maintain your 1600rpm top speed, rather than getting the lower speed range.
So many options! You're wise to take your time choosing.
Wilf
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Post by Deleted on Sept 21, 2014 16:35:37 GMT
Hello all----------- Given the looming World Energy Shortage I've opted for a more easily calculated power source and so invite you all to visit us at our new location------------
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bhk
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Post by bhk on Sept 22, 2014 9:03:17 GMT
So I'm pretty sure I've got a VFD sorted out, had a good chat with the guy over the phone today , will take 10 days to arrive from when I place the order in a a few days , he's going to forward me the manual via PDF so I can be totally sure when I order. In the mean time spent an hour in the garage tonight sorting out a light. I bought a load of these lamps a while ago as I knew they would come in handy. Ordered up a 12-24v led spot light to replace the current holder, will power it through a DIN rail power supply and a latching contactor. Ill wire the new coolant pump in a similar way so that it cuts down on the amount of buttons.
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bhk
Part of the e-furniture
Posts: 458
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Post by bhk on Sept 22, 2014 10:05:20 GMT
Hello all----------- Given the looming World Energy Shortage I've opted for a more easily calculated power source and so invite you all to visit us at our new location------------ Deer for eating, water for power and wood for the fire! I would be be set!
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Post by Deleted on Sept 22, 2014 10:56:47 GMT
---- and not a FRAKER in sight !!...........http://www.bbc.co.uk/news/uk-14432401.......
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bhk
Part of the e-furniture
Posts: 458
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Post by bhk on Sept 23, 2014 6:58:49 GMT
So got the light married to its arm tonight. Will need to pick up some 2 core wire to finish off the job later this week. Tried the light out and its super bright, 850 lumens to be precise.
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Post by Deleted on Sept 23, 2014 7:12:15 GMT
Careful--------- you'll end up with a sun burnt face !!.. LoL..
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bhk
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Posts: 458
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Post by bhk on Sept 23, 2014 7:26:09 GMT
Careful--------- you'll end up with a sun burnt face !!.. LoL.. Indeed, but at least I'm doing it efficiently with LED's
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Post by Deleted on Sept 23, 2014 8:37:27 GMT
Careful--------- you'll end up with a sun burnt face !!.. LoL.. Indeed, but at least I'm doing it efficiently with LED's ----more burn for less bucks !!..got to be good !!
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Post by Roger on Sept 23, 2014 8:57:15 GMT
Which reminds me of the time when a guy had to use an arc welder in a confined space and decided to use Gas welders goggles instead of a full mask. White circled eyes on a beetroot coloured face isn't a good look.
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Post by ejparrott on Sept 23, 2014 9:01:12 GMT
Been there done that, needs must when you're trying to put Land Rovers or horseboxes back together! Never got that bad though, he must have been doing an awful lot of welding!
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Post by Roger on Sept 23, 2014 9:37:04 GMT
I think it was inside a large pressure vessel, it was a big job.
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steam4ian
Elder Statesman
One good turn deserves another
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Post by steam4ian on Sept 23, 2014 21:58:36 GMT
Sean Just yesterday I received unsolicited a brochure regarding Lafert brand electric motors. They combine the inverter and a stepping motor to make a fully integrated variable speed drive. Link = www.lafert.com/ phone 03 9702 3707. I know nothing more about them so the usual legal indemnities apply. Regards Ian
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