Which VFD for 10 hp spindle

P = V*V / R, You can figure up to 350 volts, so at 10 ohms you need 12,250 watts.Higher ohm resisters will give you somewhat less braking effect, but also reduce the wattage needed. 350 volts is pulling a number out of the air, the VFD manual may have better info, sometimes buried in the appendix.

You can chain multiple resistors, sometimes that's cheaper than buying one big resistor. For example two 10 ohm 4000 watt resistors in series will give you 20 ohms at 8,000 watts, which would work in the above 350 volt scenario.
 
You are only dissipating the braking energy for 1-2 seconds and one is only using the VFD at 50% capacity, so one does not need giga watt sized braking resistor. Unless you use the motor with continuous braking you do not need the high dissipation size resistor, but you do need to have wire and resistor that is rated at 400VDC or higher. I would stay with a resistor in the 15-30 ohm range 1000W, if the VFD was used for continuous locked rotor braking then you would need a 1.5-2kW size resistor per the Hitachi spec. I actually have a new braking resistor that I was going to use for a WJ200-110LF install but did not use, I went with a 26 ohm 1000W metal jacked with embedded leads. If your interested I can ship it to you for $25 + postage. Otherwise I you could use the TE1000B22RJ TE1500B22RJ which are 22 ohm at 1 and 1.k5W dissipation, they are open resistors and have close to 400V DC on them, they are also quite big/long. Alternative encapsulated type would be the Ohmite BAB326615R0KE or BAB326622R0KE which are 15 or 22 ohm 1kW and about 11" x 5" encapsulated type with embedded leads.

I am not sure if you gave some thought to the control system, but you do not want to directly connect the run inputs to the switch gear, there are some simple relay circuit designs that I have used which give you bidirectional jog, differential braking, power indicator, speed control, etc. If you have some specifics you are looking for PM me and I can provide some designs and specs.
 

Attachments

  • TE Series Power Resistor.pdf
    279.5 KB · Views: 6
I don't know much about motors but I run a 10EE at work and I must say 10HP would be awesome! I have had many times when I wished the 10EE had more umph, especially when tapping large bores.
 
I always use drive warehouse. Their support is quite good. They have an invertek 5HP motor vfd that runs on 1 phase.
 
Do you really need the braking resistor? I've skipped it on all my installs. I can wait a little while while it slows down. Out of curiousity, how long does it take to slow with a braking resistor? I've always wondered about that.
 
Fyi, on braking resistors and other specialty kit, they have a Joule rating and a peak power rating. The Aluminum housed ones are generally pretty good at peak power/energy. The bigger the ceramic filled hole the more energy it will take. Wire size is critical, but hard to pre-check. Bare wire resistors are nice, but tricky to install safely. Heating elements, especially flat ones, are a great choice if you can hit the Ohms.

Sent from my SM-G892A using Tapatalk
 
The resistors that mksj posted are rated for 3x overload for 5 seconds according to the datasheet, which means they should be fine to use something significantly smaller than peak load.
 
In case you haven't found it already, Hitachi has a short app note on running from single-phase power.

I've bought a couple of VFD's from Wolf and been happy. I have a Teco and a Fuji that are in the 1 to 1-1/2 horsepower range. The Teco has more flexibility than the Fuji in how you can wire external controls, and my quick investigation gives me the impression that the Hitachi might be the same. Something to keep in mind.
 
I had not seen that a jumper between L2 and L3 is approved to prevent phase loss detection, thanks for that.
 
You must log in or register to reply here.
Back
Top