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  #1  
Old Mon 15 August 2011, 21:55
MAC2009
Just call me: MAC
 
West ST Paul, MN
United States of America
VFD Control Switch Question

Old thread but here I go Started a new thread

Gerald-persons smarter than I at this Point

I have been looking at your wire diagram,and see you have the 9V supply,fan
on the hot side of the contacter. this would mean it is you used for on / off
of at least part of the control box. I thought the isolator was left on, only turned off to gain entry.

It looks to be about 4 1/2 -5" from the bottom of the sub-panel to the center
of the DIN rail is that plenty of room or just enough.

I have read in some VFD manuals not to to use electromagnetic contacts for the line in as it may damage the board, but to use the switch on the VFD.
If this was done it would rule out the safety of the E stop for the spindle. What have you experienced with your VFD installation?


MAC
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  #2  
Old Mon 15 August 2011, 23:35
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Mac, my memory of the circuit is completely gone and I don't want to get that in my head again.

Our VFD's have stood up well. None have been burnt. They don't like too much dust (give fault messages) and have to be blown out from time to time. These days they are inside their own metal boxes to keep them clean. Boxes are the same size as the control panel with no vent holes and no additional fans.

"I have read in some VFD manuals not to to use electromagnetic contacts for the line in as it may damage the board, but to use the switch on the VFD.
If this was done it would rule out the safety of the E stop for the spindle."

The way we interpret those notes in the manuals is that one should not use contactors to switch the spindle/vfd combo on/off for its daily work....ie. every 5 minutes or so. The rare use of a contactor for an E-Stop is okay.
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  #3  
Old Mon 15 August 2011, 23:55
MAC2009
Just call me: MAC
 
West ST Paul, MN
United States of America
Thanks very much for the reply

I will come up with more

MAC
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  #4  
Old Tue 16 August 2011, 05:21
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
I agree with Gerald on his thoughts here. I have a VFD running several pieces of gear and the power feeds for these are removed when not in use just like the contactor would do each time you power up your machine. I would for sure not connect and disconnect the power each time I shut the unit off while in use for a given day. For the "Under Operation" control I use the VFD panels and remotes.
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  #5  
Old Tue 16 August 2011, 08:54
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I have seen cases where a VFD is used to set the speed of a conveyor belt or a fan, then a new electrician arrives who doesn't understand VFDs and this guy uses a contactor/starter to switch the conveyor or fan on and off. That's a no no. That's why the notes are in the manuals.

Basically, you can switch an unloaded VFD on/off with a contactor or any line switch, but don't switch a loaded VFD in this way, unless it is an E-Stop.
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  #6  
Old Mon 26 September 2011, 19:47
MAC2009
Just call me: MAC
 
West ST Paul, MN
United States of America
VFD Switching

this is a very late response, but as I an going for the record slowest built it seems proper. AS we want the Estop to shut down the VFD as well as the rest of the machine,would a second relay be need to power it up or down( not when turning )if not needed all the time.
I generally don't have a steep hill with wiring-- however the whole concept of powering and controlling the VFD AT this point has me down for the count!!!!

MAC
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  #7  
Old Tue 27 September 2011, 05:39
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
I covered that here.

http://www.mechmate.com/forums/showt...6&postcount=56

You should feed power through your main cabinet to the inputs of the VFD from your contactor on the cabinet. Then have estops on your machine so when pressed they shut off the power. Remeber they are called emergency stops for a reason !!
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