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18th Jun 2015, 10:44 PM #46Cba
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The connection for the braking resistor can be used to access the DC bus. But not all VFD's have this connections, it may not be present on economy models. If present, they are usually labelled DC+ and DC-.
I use a Tektronix THS730A handheld scopemeter, it has two fully insulated input channels. It is an old model (bought in 2001) but works fine for VFD measurements.
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18th Jun 2015, 10:52 PM #47Most Valued Member
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Mine looks nothing like that one, mine is like the ones he is currently selling.
As I understand it he orders the standard Teco in a box thats big enough to take some sort of mains filter.......without the filter, so there is room for the doubler he adds...... again I have no idea where I got this info as I've never had the cover off mine.
Given the price of VSD's these days you're like correct. Though you still only end up with a single phase which I have know what DD has done about that. Though you would have a 400V supply for any controls if needed(I think) which could be handy.
Thanks for the video(omg whats going on with that motor? just some strange mic thing?) and links
Stuart
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18th Jun 2015, 11:20 PM #48Diamond Member
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I've always associated "voltage doublers" (a bunch of caps and diodes) with high voltage but very low current circuits, but perhaps a clever engineer has made it work. By default, I'd have assumed there'd be an inductor/transformer based DC-DC converter to boost the DC bus up to a voltage suitable for switching out at 415V levels.
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18th Jun 2015, 11:22 PM #49Senior Member
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18th Jun 2015, 11:41 PM #50Senior Member
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There is different applications. Voltage multipliers like those used in negative ion generators produce high voltage but very little current.
Voltage doublers were often used in PC power supplies to allow 120/240 AC input for worldwide use. When used on 240 V systems a conventional rectifier was used. When selected for 120 V operation the input diodes were reconfigured as a voltage doubler.
These power supplies were rated at hundreds of watts so its easy to imagine the principle could be scaled up for multi horsepower VFD applications.
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19th Jun 2015, 11:44 AM #51Cba
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As mentioned earlier, VFD with voltage doubler are mass produced for the North American and Japanese markets. In those cpuntries, most residential houses only have 100 or 110 or 120V power. But their 3 phase motors are 200/400V. So there exists a huge market for 100V in and 200V out VFDs.
Whereas in 220/240V contries, all newer 3 ph motors are 220/380V, so they can be hooked up directly to a 220V in VFD. There is only a minuscule niche market for customers owning an old motor or machine that only hooks up 380V, and are unwilling to upgrade their old motors. Drives Direct in the UK seem to cater for this very small niche market by adding a voltage doubler to 200V VFDs - at a considerable premium though.
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19th Jun 2015, 12:04 PM #52
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19th Jun 2015, 12:31 PM #53Cba
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19th Jun 2015, 01:15 PM #54Most Valued Member
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I'm not so sure about that. If you are comparing apples with apples. The cost of a new 2.2kW Teco in au would seem to be $1080. So DD isnt to bad compared to that.(anyone know the UK price of one?)
It will be interesting to find out just what the OP has. If he has to bring out the star point its not the end of the earth. Who knows he maybe happy with half power, my camel back is.
Stuart
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19th Jun 2015, 05:20 PM #55Cba
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If you want to compare apples with apples, you have to compare the street prices, not the heavily inflated list prices aimed at industrial customers that anyway receive 30%+ trade discounts and do not pay GST.
Street price for a brand new 2.2kW-3HP sensorless vector TECO is AU$261 plus AU$82 postage:
http://www.ebay.com.au/itm/3HP-3PH-4...item1c54a30793
A 3HP VFD from Drives Direct is 475 pounds or 950AU$ plus postage. Not sure if it is an US made TECO though, nor does it anywhere mention it is a modern sensorless vector drive. Direct Drives put their own nameplate and labels over the makers markings. And chances are you could be slugged by our customs for GST if purchase price plus postage exceeds AU$ 1k.:
http://www.ebay.co.uk/itm/3-HP-DIGITAL-240V-415V-3-PHASE-INVERTER-CONVERTER-BRIDGEPORT-MILL-LATHE-/381284366136?pt=LH_DefaultDomain_3&hash=item58c651b738
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21st Jun 2015, 09:11 PM #56
I have made progress with the VFD and my motor. Thanks allot to NCArcher who helped me via email. The process was relatively simple thanks to plain & simple instruction from NCArcher.
End the end the motor worked fine without need to make any changes. There was no need to add a 20 amp circuit to the house.
All I needed to do was purchase some 400 volt rated round lugs and forked lugs and good crimper. It took about 20 minutes and the VFD started up then I simple pressed run and the motor started up. The next step is to program the VFD. Here are some photos.
IMG_4736.jpgIMG_4737.jpg
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21st Jun 2015, 10:12 PM #57Golden Member
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21st Jun 2015, 10:19 PM #58
The motor hums along nicely with a soft high pitch whizzing sound. It starts slowly revving up over 6 seconds as the hertz increases on the display. The VFD makes more noise in all honesty.
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22nd Jun 2015, 12:09 AM #59Most Valued Member
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22nd Jun 2015, 12:21 AM #60Golden Member
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