Originally Posted by Seth
I wouldnt see any reason for a load reactor. I have never messed with a load reactor but as long as the VFD is setup properly for a motor then you shouldn't have any problems. I guess I could see where you would need one if you had a very expensive drive, then you will need to take all the precautions you could.
Only time I have used a line reactor is when the input voltage going to the drive was a little too high.
You have little experience with drives from your statement. Professionals setting up VFD's use line and load reactors all the time. Line reactors are a simple 1:-1: ratio transformer. They do not change voltage. They condition voltage. They prevent nuisance tripping, and adjust impedance. They are listed by their impedance value in all manufacturers catalogs.
Load reactors suppress spikes associated with VFD PWM. These spikes at 460 can be as high as 1500 volts. The load reactor does a good job of reducing these spikes to where they are not apparent visually on the scope. These spikes if not controlled will cause pin hole imperfections in motor windings, and eventual motor failure. That is why most all motor manufacturers use a special coated magnet wire. Baldor Electric trademarks theirs as "Spike Resistant".
If you are using a motor not designed for inverter duty, the load reactor may just be the answer. So, the load reactor is a very important option.
Distance from control to motor may require the addition of a load reactor.
It is fairly standard throughout industry that distances of more than 100' require a load reactor. Long distances produce a phenomenum call "Ring Up Voltage" This is an audible whining sound that can be very irritating in office or hospital settings and can overheat the motor.
The addition of the new VFD output cables are helping greatly in this regard.
Finally. Line reactors are good insurance. So good, that many manufacturers will sell the line reactor for 1/2 price when ordering a control and motor. (Baldor). They are inexpensive and could save you many headaches in the future. I recommend line reactors on all drive inputs.
Load reactors should be considered and implemented when distance and noise is an issue.