IGBT effects
IGBT effects
(OP)
Another engineer has told me that I need to locate my MCC closer to my motor loads " to limit IGBT effects on the system". I have a few medium loads between 30 and 60 hp. Could anyone provide a brief explanation about the determental effects of lengthy cables and how this is related to transients from IGBT switching?





RE: IGBT effects
Usually, there is no MCC between VFD and motor. It is only when you have several parallel motors on one VFD that you need to protect the motor using an MCC. In situations where you have one VFD and one motor, the protection is built into the VFD.
Gunnar Englund
www.gke.org
RE: IGBT effects
With IGBT switching in VFDs, there is a transmission line voltage reflection effect that creates high voltage spikes from the square voltage pulses. There is a critical cable length that plays a role in that effect. Anything more than 25 feet is likely to be a problem. If you can put the VFDs really close to the motors, the voltage spikes might be eliminated.
For withstanding voltage spikes and for other reasons, it is also important to use only motors that are rated and nameplated for use with VFDs. There are also VFD output filter units (output reactors) that are designed to reduce voltage spikes. With VFD duty motors, perhaps with filters, the motor cable length won't matter so much.
RE: IGBT effects
RE: IGBT effects
I'd say you should be safe by using the VFD's combined with output reactors in your remote location. There are also DV/DT filters (motor guarding filters) that do a better job than just a reactor. I definately would not mount your VFD's in a washdown area.
If you google something like "vfd reflected wave" you will find tons of info on the effect. However, every VFD, cable and motor combination behaves differently so it's very unlikely you'll find any useful hard data.
RE: IGBT effects
Gunnar Englund
www.gke.org
RE: IGBT effects
MCCB = Molded Case Circuit Breaker
RE: IGBT effects
Gunnar Englund
www.gke.org
RE: IGBT effects
As mentioned there are plenty of solutions out there for the kind of distance you are looking at. Seeing that you used HP instead of kW it appears you are in N. America. Look at MTE, TCI and Hammond for info on load reactors and filters.
Suggestions for cables: Belden (website works on MSIE only), Alpha, and Lapp
http:/www.jraef.com
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: IGBT effects
RE: IGBT effects
RE: IGBT effects
RE: IGBT effects
I am actually very sure that you are wrong.
Where did you get that information?
Gunnar Englund
www.gke.org
RE: IGBT effects
They reduce HF components, but not harmonics.
Gunnar Englund
www.gke.org
RE: IGBT effects
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