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  #1  
Old Wed 07 May 2014, 14:38
Tokamak
Just call me: John #121
 
Monrovia (ca)
United States of America
Safety Disconnect for Spindle

I'm completing my wiring diagram and want to have a power disconnect for the spindle when changing bits.

The power could be disconnected at the source powering the VFD.
or
Place a disconnect between the VFD and the spindle (on the Y Car).

One way cycles power to the VFD the other does not.

Is it safe for the VFD to have its output disconnected with main power on to the VFD (spindle not running per Mach3 command)
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  #2  
Old Thu 08 May 2014, 19:03
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
You should not put a contactor or disconnect on the load side of the VFD unless it is specified by the manufacturer. Woods and Vacon drives allow for a contactor on the load side as long as certain parameters are set in the VFD so it will not destroy the unit. Some VFD manufacturers have a safety circuit built into them to disable the motion without having to disconnect power from the units. This circuit is complaint with known safety protocols and typically used with a double redundant self checking circuit. Powering off the entire unit you have to make sure the settings are correct so it does not start up in run when power is restored.
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  #3  
Old Thu 08 May 2014, 20:23
Tokamak
Just call me: John #121
 
Monrovia (ca)
United States of America
So the 2 real choices are power on/off button on the VFD or removing the power from the VFD. I suppose that Mach3 doesn't care either way as long as the VFD completes it's initialization before telling it to continue.

Thanks for the explanation. I'm getting a China Spindle and will power the VFD thru a contactor that is controlled thru a flow switch. I can disconnect there.
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  #4  
Old Fri 09 May 2014, 21:13
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
I will post this to help further browsers and researchers. If you want a VFD with built in safety options I recommend the Hitachi WJ200. Proper use would be with a safety monitor relay as shown in the picture because it has intelligent sensing to verify the circuit is indeed safe. This would be wired through the two normally closed contacts that would feed channel 1 and 2 with setup being auto-reset or use a 3 position emergency stop so the pull-to-start action would engage the reset on the safety relay. The connection between P24 and GS1 & GS2 must be activated at the same time. You could use 2 sets of NC contacts (4 total make-break contacts) and series through each set without a relay. This would give a double redundancy but lack self checking aspect for protection that a safety circuit is to be designed around. The theory here is that with a maintained button the chances of all 4 contacts sticking are minimal. Safety monitor relays can as cheap as $100 USD and a expensive as $500 USD. When thinking of the value of your hand, it is a small price to pay for protection. As with all safety devices, periodic checks are to be done to verify the working circuit.
Attached Images
File Type: jpg wj200safety.jpg (42.6 KB, 152 views)
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  #5  
Old Sat 10 May 2014, 00:36
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Pete, are you talking about something like Pilz Pnoz units? I have been researching those since I have been working on my wiring diagrams. You wouldn't happen to be able to post a link to the full size image?
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  #6  
Old Sat 10 May 2014, 17:33
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Pilz, PNOZ, Allen Bradley, Sick, ABB Jokab,... there are many brands but all you need in a monitoring relay. The Jokab RT9 is the most simple I have wired up and very dependable. However I have wired every flavor I have listed. I have installed many on robot installations with a deadman setup but I do like the ABB ease of wiring and schmatics the best. Jokab Safety

The image is straight from the Full Hitachi WJ200 User Manual.
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  #7  
Old Sat 10 May 2014, 17:54
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
The image the manual has uses a feedback option. All that is really required is to feed one side of the two safety relay outputs contacts with P24 from the drive and have those feedback to GS1 and GS2 from the other side respectively. Your monitoring circuit would be supplied by the manufacturers suggested input supply terminal, in this example a single 24VDC to the ESTOP dual NC contact blocks and from the other side of the contact blocks, these two wires feed the input circuits (2). Both have to be open and closed at the same time or the safety relay cannot be reset. However, there is 24VDC provided by the drive, I would not try to power the safety relay with it but rather a separate power source. This will disable the drive and will not run even if the run command is sent to the drive. I can provide a print of a basic layout if you would like for the RT9. Since all manufacturers have there own wiring scheme, not one will apply to another.
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  #8  
Old Sat 10 May 2014, 18:10
IMMark
Just call me: Mark #119
 
Columbus Ohio
United States of America
Pete, just FYI the link you provided doesn't appear to be working?
Mark
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  #9  
Old Sat 10 May 2014, 18:13
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
www.jokabsafetyna.com/product-lines-index/safety-relays

Try this. I tested it in the advanced section
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  #10  
Old Sat 10 May 2014, 18:21
IMMark
Just call me: Mark #119
 
Columbus Ohio
United States of America
Yep...that one is working. Now if you can add an extra 40 hours to my week, so I can try to learn this stuff
Mark
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  #11  
Old Sun 11 May 2014, 00:46
KenC
Just call me: Ken
 
Klang
Malaysia
If you don't want to hire someone to do it for a fee, you will magically have an additional 100hr per week.
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