Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Robotintheforest on January 15, 2018, 08:32:55 PM

Title: Switch between wall plug and VFD?
Post by: Robotintheforest on January 15, 2018, 08:32:55 PM

Hi I have just received my replacement HY VFD for my 2.2kw spindle and I am looking at the manual and it says:

"No contactor should be installed between the power supply and the the inverter to be used for starting or stopping of the inverter. Otherwise it will affect the service life of the inverter."

I have a 220v switch between the plug and the VFD and have been using that to switch the VFD on and off but now I am wondering if that is how my first VFD got burned out. Can any of the VFD experts out there confirm this? Should I be plugging and unplugging the VFD every time? Would moving the switch between the plug and the panel make a difference?

Thanks

Title: Re: Switch between wall plug and VFD?
Post by: joeaverage on January 15, 2018, 09:07:10 PM

Hi,
it is certainly not recommended that a switch or contactor be used to turn the VFD off under load. In an ermergency
yes do it but as a means of turning your motor off...no don't do it.

The probability of failure because the primary supply was switched (while driving a motor) is low. Switching on and off
between sessions should not cause any problems.

VFDs are pretty high-strung units and failures are not uncommon. Better and more expensive brands are more reliable.

Rapid deceleration of the motor causes a VFD considerable over voltage stress, even with a braking resistor. Do yourself
a favour and allow gentle deceleration when programming your drive.

Craig

Title: Re: Switch between wall plug and VFD?
Post by: ger21 on January 16, 2018, 06:49:58 AM

I think that what they are really saying is to not turn it on and off frequently, like to change tools, or use it for an emergency.

On commercial machines, the VFD is connected to the main power supply, so it remains on as long as the machine is on.

I would think that the switch would be fine, if  you just use it to turn it on and off.

The problem comes in if you accidentally flip it on and off rapidly.

Title: Re: Switch between wall plug and VFD?
Post by: hmoore01 on January 16, 2018, 08:15:41 AM

I use freq drives in my line of work. When you power one down you must wait for the drive to properly shut down for a few seconds, or risk the chance of it going into fault.
Once it faults you will then have to reset the drive before it can start up again. You dont just unplug your computer, to turn it off. It shuts down a bit in the same way.
It also stores power for a few seconds til it dissipates. 

Title: Re: Switch between wall plug and VFD?
Post by: wmgeorge on January 16, 2018, 08:41:15 AM

Quote from: hmoore01 on January 16, 2018, 08:15:41 AM

I use freq drives in my line of work. When you power one down you must wait for the drive to properly shut down for a few seconds, or risk the chance of it going into fault.
Once it faults you will then have to reset the drive before it can start up again. You dont just unplug your computer, to turn it off. It shuts down a bit in the same way.
It also stores power for a few seconds til it dissipates. 

  Ditto, used to install a few and never ever break the output to the motor with a relay or switch while they are under load!

Title: Re: Switch between wall plug and VFD?
Post by: Robotintheforest on January 16, 2018, 01:00:12 PM

Thanks all, I am only using the switch for beginning and end of day power up/down.