VFD spindle control safety

[AndyUK]

You are correct - as far as providing a completely safe solution you would require to disconnect the supply. The manual does indicate an electromagnetic contactor (relay) but notes that this should not be used as a general on/off control.

I ordered a relay the other day intending to use it for exactly that function, then I read this in the manual. I'm sure I'll find another use for that relay, so the £5 I've spent on it is immaterial, but whats the reasoning for this exactly? Is it the noise that the VFD is spewing out, or is it more of a surge current thing?

[Doddy]

I ordered a relay the other day intending to use it for exactly that function, then I read this in the manual. I'm sure I'll find another use for that relay, so the £5 I've spent on it is immaterial, but whats the reasoning for this exactly? Is it the noise that the VFD is spewing out, or is it more of a surge current thing?

I wouldn't like to speculate, however, wording from the manual:-

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

My guess (and it is a guess) is that these have been engineered by an accountant and power-up surges, and inductive EMF stress the power components.