Originally Posted by
Bert Delisle
With most modern VFD controls the normal operation of start and stop are momentary push button switches, these switches usually are wired to programable "inputs" to the VFD to send pulse instruction to the vfd.
The E-Stop button is usually a "maintained" switch which means the signal is maintained off and must be manually pulled or twisted to turn it back on, usually wired to programable "input".
Depending on the VFD initial programming the "braking" function of the vfd under normal stop/start may be different than the E-stop "braking" function. E-stop likely will apply more braking action to stop the rotation quicker, based on the factory setting from the manufacturer of the lathe. Or it may simply just remove the run command and the work piece would just coast to stop.
In both cases the power to the computer /programable board and the DC buss is still applied. This means the computer portion, the cooling fan, and the DC portion of the inverter are still energized and ready to respond to operator action.
The cooling fan is important to keep running as the heat sinks used in the VFD can get very hot while running and need time to cool down, the fan is likely temperature controlled(mine is, I can hear it running, and it stops several minutes after a period of down time), lathe is still ready to run, just the internal VFD fan has stopped,
Switching off the main power switch or unplugging the cord will remove the incoming power totally resulting loss of cooling to these heat sinks and could result in damage to the electronic speed control components of the drive.
I suspect that the comments related to VFDs not liking "power off" switches in the main power line may be due to overheating of components because fan power was shut off.
Adding a remote stop start push button is a great convenience and safety feature, my magnetic remote switch box lets me place it where it is most convenient for me, out of the line of fire.