VFD and Light Curtains
VFD and Light Curtains
(OP)
Is there an industry standard means of connecting a light curtain with a VFD. I often design fractional VFD systems that rotate tables for operators to manufacture parts. I usually wire the light curtain to a safety relay, then tie two positively guided contactors from that relay to drop out the three phase power to the motor. The problem is that frequent (5-10 times a min) tripping of the incoming power to the VFD causes long startup times and I imagine is hard on the VFDs themselves. I can't find a manufacturers recommendation to safely disconnect the power to the motor on the load side of the VFD, and most installation manuals say not to do this. Any suggestions would be appreciated.





RE: VFD and Light Curtains
RE: VFD and Light Curtains
Are your operators using the light curtain as a stop/start control instead of as a safety device. If they are using it as a stop/start why not connect it to the stop/start circuit and have a secondary safety system like a dead man switch that takes out the power supply.
I think in practice all modern VFD's have a current limiting/soft charging system built in, but check the manufacturer's guide on the acceptable number of power ups in a given time period.
RE: VFD and Light Curtains
http://www.ae.ucdavis.edu/projweb/csdg.nsf/(index)/16483+Variable+Frequency+Drive/$file/16483+Variable+Frequency+Drive+03.pdf
(by copying it into the browser)
for: abrupt operation of VFDs due to abrupt switching of VFD bypass contactors.
Operational manuals are supposed to describe abrupt operations of VFDs.
RE: VFD and Light Curtains
RE: VFD and Light Curtains
RE: VFD and Light Curtains
I'm not sure where in the world you are but if you contact Siemens A&D (or in the USA it's Siemens Energy & Automation)and ask for the MCPM department I'm sure somebody will provide details.
RE: VFD and Light Curtains
Control Techniques UNIDRIVE SP got this feature as standard.
(NO options needed).It is caled SECURE DISABLE-function and it meets the requirements of EN954-1 : category 1, 2, and 3 for machine safety.
RE: VFD and Light Curtains
Thankyou for that information. I now have a solution looking for a problem, and I know that problem will officially land on my desk in about two or three months.
Regards to you both.
RE: VFD and Light Curtains
http://80.253.105.183/features/secure.shtm
http://www.imakenews.com/powermation/e_article000105246...
http://www.controltechniques.com/products/sp_secure.htm
etc. for more info on secure disable unidrive
RE: VFD and Light Curtains
Quando Omni Flunkus Moritati
RE: VFD and Light Curtains
RE: VFD and Light Curtains
As far as I know this is NOT a recognized standard in the U.S.A.
Does anyone know whether this approach to safety has been approved for use by the relevant organizations [OSHA, NFPA79 etc. etc]
RE: VFD and Light Curtains
However, the manufacturers, e.g. Carlo Gavazzi
http://gavazzi-automation.com/ac/pdf/CGSol03-ENG.pdf
are adopting foreign standards according to their needs (for "industrial automatic doors").