[bunalmis]

My step motor driver work by DC 100V and all logic I/O pins of driver are optical isolated.

I don't want to use line transformer for power supply. I can produce 100V DC from the direct hot line by step down type electronic regulator.

At this condition: Any coils to earth voltage will be 220V.

Stepper motor catologs give the dielectric strength value is 500V AC for one minute.

Is it risk for human life if i use non isolated step down regulator ?

[pastera]

The coils will not see the full 220 (actually ~311 rectified) unless your switch element goes bad. I would put an overvoltge crowbar in for safety.

Are you designing the switching regulator? if so, why not switch to an isolated design.

Either way you need to be carefull with the wiring as 100V is considered a hazard isolated or not.

Aaron

[bunalmis]

Non isolated switching regulators are simple and cheaper then smps. Therefore I want to use.

Yes SMPS eliminate the isolation problem but this is second solution for me.

I want learn the coil to motor body isolation is bad or good at the step motor?

What does it means these?

Insulation Resistance: 100M Ω Min. ,500VDC

Dielectric Strength: 500VAC for one minute