VFD wiring

I do not recommend leaving the VFD on all the time if you are not using the machine, it is a liability if anyone else is around and there is some component life issues. It is not a good idea to turn a VFD on/off frequently, so if you using the machine through the day leave it on and then turn it off at night. Line surges from lightening strikes, the effect on components depends on the distance, what it strikes, voltage, current and if you have have any type of surge suppression/fusing. When I lived in Tucson we had pretty severe lighting strikes during the monsoon season, I put an industrial surge suppressor at the main electrical panel and at my sub-panels and never had an issue, my neighbors where not so fortunate. In bad electrical storms I would turn the power off to my machines at the machines and sub-panel.

Also a reminder that the VFD charges capacitors for the DC buss, it takes about 5 minutes for the VFD to totally discharge the capacitors. If you turn off the VFD, wait at least 5 minutes before turning it on otherwise it could cause damage the current in-rush circuit/components.
 
mksj said:
Also a reminder that the VFD charges capacitors for the DC buss, it takes about 5 minutes for the VFD to totally discharge the capacitors. If you turn off the VFD, wait at least 5 minutes before turning it on otherwise it could cause damage the current in-rush circuit/components.
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Can you explain that better? A capacitor that is discharged will experience/create a much larger inrush than one that is charged, so I'm not following the logic.
 
The inrush circuit is active when the capacitors are discharged and use a relay/switching device to place a resistor/thermistor into the circuit upon power up, if the circuit is not completely discharged it may not function correctly and you will not soften the inrush current which can be significant. There is also a heating cycle on the inrush components, frequent on/off cycling can cause quicker failure of the components according to others that design/repair VFD's.
 
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