kolyur
Lifetime Supporting Member + Moderator
I've noticed that many VFDs and servo drives I've used have a warning in the manual that the line power should not be cycled too frequently. Usually it specifies some amount of time, say 30 seconds to several minutes, that the device should remain 'off' before applying power again. What's the purpose of this delay? I suspect it has to do with capacitor drain/charge time but how can it be detrimental to the drive?
The reason I ask is that I'm using a simple stepper motor drive in my current project that doesn't have a typical 'enable' signal. (When line power is applied, the motor immediately has holding current.) I'm trying to decide how to implement the emergency stop function. I'd like to put a contactor on the line power but the manual states that power should be off for 15 seconds before re-applying. That will usually be the case with an E-stop, but not always. I'm concerned about whether occasional quick power cycles will significantly reduce the life of the drive.
I've already contacted the manufacturer and they had no good advice other than restating the 15-second rule from the manual. They did suggest using the "All Windings Off" drive input, which releases holding torque, but I've discounted that because it is an active low signal (signal on = motor off) which is not appropriate for a safety function.
The reason I ask is that I'm using a simple stepper motor drive in my current project that doesn't have a typical 'enable' signal. (When line power is applied, the motor immediately has holding current.) I'm trying to decide how to implement the emergency stop function. I'd like to put a contactor on the line power but the manual states that power should be off for 15 seconds before re-applying. That will usually be the case with an E-stop, but not always. I'm concerned about whether occasional quick power cycles will significantly reduce the life of the drive.
I've already contacted the manufacturer and they had no good advice other than restating the 15-second rule from the manual. They did suggest using the "All Windings Off" drive input, which releases holding torque, but I've discounted that because it is an active low signal (signal on = motor off) which is not appropriate for a safety function.