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About LinkBacksHello, I have an old Bridgeport J head with a 2hp 3 phase motor. I want to use a VFD for speed control as well as for ON/OFF and FWD/REV. Do any of you have any suggestions on what brand/type works best for this application?
Thanks,
Scott
Hello, I have an old Bridgeport J head with a 2hp 3 phase motor. I want to use a VFD for speed control as well as for ON/OFF and FWD/REV. Do any of you have any suggestions on what brand/type works best for this application?
Thanks,
Scott
I use a Hitachi SJ200-015 with that same size motor. You'll need a braking resistor, unless you like 10 second accel/de-accel ramps. I used a 120 volt 300 watt (50 ohm) car block heater - works great...
You can buy the Hitachi and others from www.driveswarehouse.com...
Thanks, that's the one I was considering, called driveswharehouse and they confirmed it as well. I asked them about a braking resistor, they quoted me an additional 181.00is there anything else I can use that may look a little less, well like a block heater?
Scott
Would a 97 ohm 300 watt braking resistor work? does it have to be exactly 300 watts and 50 ohms?
Is that just a resistor or do they call out a braking unit or something, I don't know if it is that easy on that drive......not at all sure tho....
I too am using the Hitachi. Works great but dont find the need for a resistor. What am i missing?
9 1/2
B.C.I.T. Machinist CNC
Do you have that plugged into the bottom of your coolant tank?????Originally Posted by lakeside53
archie =) =) =)
It would work but it it won't provided a whole lot of braking torque. The minimum (for the 015) is 35 ohms... I choose 50 'cos that's what I had.
there is a table in the user manual that shows the relationship between resistance and braking torque.
The high wattage just helps with the duty cycte. Again, there is a table that show that relationship.
That drive has a braking unit built inside. So yes, it's that simple. The OEM resistor has a Nema cage and a thermal cutout, but they are expensive.
If you accept longish ramp down and up times, you generally won't need it. I like the precision of a short start/stop cycle.
It also depends on your motor size and construction. My US Motor 2hp really kicks out the voltage (386 or so... ) when it turns into a generator!
$181 - that's just for one, and you'll likely need THREE for high performance braking!Thanks, that's the one I was considering, called driveswharehouse and they confirmed it as well. I asked them about a braking resistor, they quoted me an additional 181.00
Scott
Search ebay for "OHMITE" or "POWER RESISTOR" etc... many many surplus high wattage resistors available from $3 to few 10's. Slap in a high wattage device and you can forget about the thermal cutout etc. make sure it's vented and protected from chips. I prefer a separate compartment from the controller for that type of resistor. My "block heater" is connected via thermal grease to a heatsink in the top of the enclosure.
300-400 watt 120v "anything" will work well as a braking resistor (check your drives' minimum resistance)... coffee pot heater... etc
Here's one of my installations.
http://s238.photobucket.com/albums/f...de53/BP%20VFD/
The "block heater" is attached to the slab of aluminum plate in the top of the enclosure. Also... I modified the motor so it had a fan switched by the VFD relay contact (to provide cooling air even at low motor speeds).
The big black contactor is so I have a front pane; "one switch" power disconnect for the 220 and the 4 120 volts plugs in the bottom of the enclosure.
Last edited by lakeside53; 08-04-2008 at 11:05 PM.
Thanks for all the info lakeside, I didn't realize that the resistors are as large as they are. After doing some research, I think the block heater is a neet idea. Do you happen to recall the brand and model, I'm having trouble finding a 300 watt. The guy at drives wharehouse told me that the minimum for ohms for this model is 50 BTW.
Scott
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