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#210568 - 07/10/13 01:04 PM reactors on vfds  
twh  Offline
Member
Joined: Mar 2004
Posts: 916
Regina, Sask.
Have you ever had a problem with a vfd that was resolved by adding a line or load reactor?

Sometimes I feel like I'm buying a rabbit foot for luck. If I install the reactor and don't have a problem, maybe I wouldn't have had a problem anyway. The time I had a problem, reactors didn't help.


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#210570 - 07/10/13 07:29 PM Re: reactors on vfds [Re: twh]  
sabrown  Offline
Member
Joined: Dec 2002
Posts: 302
Ogden, Utah, USA
This is a tricky question (besides harmonics there is interference issues). Simple answer I have not, but then again I've not had the opportunity to fix an issue.

Several things should go into the decission before buying a reactor, for just placing in reactors in several locations on the same source can cause problems through harmonic interactions and you end up with worse problems than what you started with.

So, how much of the locations load is VFD's?
How big and how many are there?
What is the patern for operation, so maybe an interactive unit (assumeing there is such a beast) is needed.

It comes down to needing to get it engineered by an engineer with experience in the area. I am not one with the experience in this area and my limited knowledge almost pre-dates VFD's.

TC-ER cables or XHHW-2 conductors in metal conduit may be all that is needed thus sheilding other things from the interference.


#210571 - 07/10/13 08:48 PM Re: reactors on vfds [Re: twh]  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Think about it: exactly what is a reactor?

It's a big coil of wire. Half a transformer. What can it do?

All it can do smooth out 'bumps' in a less-than-perfect DC supply, and alter the impedance of the circuit.

So, any effect would appear as better speed control and cooler motor windings.

With that in mind, I have no doubt there are plenty of folks who routinely bypass them, and claim things work just fine. For a similar reason, I often find braking resistors disconnected. Who needs them?

Well .... let me put it this way: Every time we get a factory rep out, he makes problems disappear, usually by simply restoring everything to its' original configuration. That's followed by a year or two of 'field improvements,' a complete failure, return of the factory rep, and the cycle repeats.

Another common thread to problems is the equipment being run way beyond its' intent. 12-ton cranes are not really meant to lift 12-tonnes all day long, but the company 'saves' by not buying the 15-ton crane. Small wonder that two years later the crane (or whatever the machine) is thoroughly hated five years later by the maintenance crew.


#210573 - 07/10/13 11:02 PM Re: reactors on vfds [Re: twh]  
twh  Offline
Member
Joined: Mar 2004
Posts: 916
Regina, Sask.
I have the manufacturer's recommendation on when to use line and load reactors. Sometimes they think they aren't necessary.

I'll ask the question a different way.

Has anyone not put reactors on, when the manufacturer didn't recommend them (or otherwise), and later had to add reactors to resolve an issue?


#210597 - 07/12/13 12:05 PM Re: reactors on vfds [Re: twh]  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
The need for reactors cannot honestly be answered by the manufacturer at the time of purchase. Except for extremely cheaply engineered VFDs, manufacturer recommendations for reactors are usually based on the philosophy of 'better safe than sorry'.


The need and benefit of reactors can only be determined determined by the installed system.
Installing reactors into existing circuits is harder than putting them in during the initial installation.




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