VFD Choices - Automation Direct, Hitachi, Teco, .

[Paul Titchener]

I need to get a VFD for the Clausing 5914 that I'm rebuilding. It has a 2 HP 3 phase motor.
I haven't used a VFD before, but in addition to the variable speed, I like the idea of braking and automatic reversal. I want to spend less than $300. and it looks like that puts me in the range of units from Teco, Hitachi and Automation Direct.

The lowest price new unit looks like the Hitachi from dealerselectric.com for $250., but as far as I can tell, it has no braking capability unless you buy an additional add-on, is that true?

In addition to braking, I'm hoping that alll these units can be re-programmed to display the actual spindle frequency rather than motor voltage frequency, is that true?

It looks to me like for the price you get the most freatures from the GS units from audiomationdirect.com.

Does anybody have any experience with these units they could relate or suggestions for other units to look at?

Thanks,

Paul Titchener

[brent]

I have a TECO I got from dealers--- pretty cool gizmo--- and I programed mine to show spindle speed. it will brake with out a resistor somewhat, if you set it to decelerate too rapidly it trips. for an instant stop (.5 second) you should use a resistor. I just did the trial and error method to set my parameter for decel so that it doesn`t trip. brent

[BillSct]

I just bought a TECO FM100 2 hp form dealerselectric for $246.00 plus shipping. haven't got it running yet so I can't tell you what I think.

[Doozer]

I have a Hitachi SR100(?) and this is the better flux vector model. This feature is much better than regular volts/hertz type. I have mine on a bridgeport and you can set the freq for 5hz and grab the drill chuck and try to stall it. The unit senses the additional load and kicks up the current, spinning the chuck from even the tightest grip. It is like someone floored it and kicked in the passing gear! No problem with power tapping, even the biggest taps. It has a multiplier you can enter to scale the hz to read actual motor speed or spindle speed. Yes it works OK with no brake resistor but you can really slam it if you have one. I have a 1hp drive and I used a heater element from a hair dryer for a resistor. Works great. I can slam the speed to 120hz and to zero and back again as many times as I want, and the element gets only slightly warm to the touch. Others have suggested electric range elements. I am now needing a 3hp drive and I think I am gunna buy another hitachi, cause I love the power down low. Ordered it from automationdirect.com and ups brought it the next day, wow. Have fun, these are fun toys. --Doozer in Buffalo

[mhubler]

If you buy the TECO, be sure to downlaod the manual that Bodine has (same VFD, different name), it is MUCH better.

http://www.bodine-electric.com/pdf/micro.pdf

If you need to stop NOW, just add a brake resistor (I would be careful if you have a threaded chuck... would not want it to come off). The brake resistor is basically a power resistor. My 2hp TECO requires a 100 ohm, 200 or so watts. I found one surplus for $8.00. The wattage can be higher, but lower is not a good idea. Some others on this board have used the elements out of water heaters, electric ranges, toast ovens, hair dryers, etc., as the power resistor... just make sure the ohms are right.

[JimH]

I have two Teco's. Got both thru Dealer's. One is 1.5 hp and the other 3 hp. Haven't got the 3 wired up yet. Got a new lathe to go with it!

Where did you find a load resistor for $8? I have been searching for a cheap source but have not been successful.

J

[mhubler]

I found the power resistor at a local surplus store - Halted (HSC Electrical Supply). I bought 2 - 200 ohm, 100 watt resistors and mounted them in parallel to get 100 ohm, 200 watt. These resistors are coils wrapped around a ceramic tube core. I am sure there are other surplus stores in your area or on the internet. I check Surplus Sales... they have a 200 ohm 90 watt resistor for $8.50 each (times 2).

http://www.halted.com/

http://www.surplussales.com/resistors/ww115-250.html

(I read on this board that some are using light bulbs as power resistors... might check the ohms to see if it would work)

Hope this helps.

[JimH]

Thanks for the pointers. I'll check them out.

Note that mounting your two resistors in parallel does provide you the resistance value you are looking for, however, the wattage capability is remains that of the smallest part. In other words, for your example when mounted in parallel, you get 100 ohms but the wattage stays at 100 watts. How warm do they get?
J

[gglines]

Paul,

I have 3 Hitachi units. I've bought from Automationdirect which is a very good outfit, and also from an eBay seller as well who was slightly cheaper.

You need to attach an external braking resistor for quick stopping. The Hitachi units are expensive ($180 I think) in the size you need, but work well. I don't think braking resistors are complicated, so perhaps an electronics wizard can be found on the web that could point you to a cheap way to make one.

The Hitachi units display the frequency by default. You can enter a constant in a register and have that display to show you your RPM instead of the frequency, but that would only work on one belt setting. The frequency is mulitplied by the constant and that is displayed. For example, if the spinde was turning 1200 RPMS at 60hz, you would enter 20 in the register. Then, when you turned the pot down to 50hz, 1000 RPMs would be displayed. If you changed to back gear or changed belt settings, you would have to input a new constant to read the correct RPM though.

What I do instead, is make a chart in Excel that I post to my mill. It gives me the RPMs for every 5hz from 10hz to 120hz on one belt setting, and the back gear. I haven't moved the belt on my mill in 2 years.

George

[mhubler]

I am no expert on VFDs or brake resistors. From what I have learned, the amount of wattage required is related to the weight of the rotating mass (kinetic energy) and the amount of time allowed to reduce the speed. Thus the required wattage for a 2 hp lathe with a heavy chuck and a 2 hp mill with an end mill will be different. Here are a couple of links that explain it a whole lot better.

http://www.baldor.com/pdf/manuals/701-202.pdf

http://www.vacon.it/Supporto/Vacon%20CX ... ud219c.pdf

In answering the question of how hot the resistor gets, not very as far as I know. The VFD on my mill is set for 3 seconds for braking, with very little in the way of rotating weight.

Touching on what another poster mentioned. I have my VFD set to read 1.000 at 60 hz. So when I need to set an RPM, I just divide the required RPM by the name plate RPM for that belt setting, and set the VFD for that proportion. The VFD is also set for overspeed of up to 90 hz., so you have the option of running overspeed on a lower belt setting or underspeed on a higher belt setting to achieve the same desired RPM.

[BFlint]

Paul,
I have one of the GS1 units from Automation Direct. I thought it was a great bargain given all of its capabilities. I have a 1/2 hp unit on my Burke milling machine, and the programming flexibility is amazing. Your can program braking time, ramp up time, min/max speeds, etc., and have it display spindle speed, frequency, amperage, or whatever you want. It also has control connections so you can hook up external controls of different sorts. The most obvious use is to set up a convenient reverse switch. Quality of the unit is excellent.

Automation Direct is a great company to deal with. When I bought my unit, the price was $159. Two weeks later I saw they had lowered the price to $119. They refunded me $40 no questions asked.

B Flint

[upstart]

JimH, the two 100 watt resistors in parallel have a total wattage of the SUM of the two, because they are equal.

So the example is 200W worth of resistor.

If they are not the same value it becomes more complex to figure the relative powers.