Hi everyone!
I'm planning to build a small machine tool using a three-phase AC induction motor (squirrel-cage type) driven by a VFD.
The motor is to drive a metal platter directly, wihout a belt. In other words, the platter will be mounted directly onto the motor shaft.
The operator will have his hands above the platter.
My question is: is there a risk of electric shock should his hands touch the platter for an instant? (for the sake of the discussion, let's ignore mechanical injuries and focus on electrical safety only)
What is more, the machine may be operated in an old building with an old electrical installation, which may have a bad earth connection or even no earth connection at all. So maybe my question should be split into two cases:
(a) Assuming the whole system is perfectly grounded, is there a risk of electric shock should the operator touch the platter?
(b) Assuming the system is not grounded, is there a risk of electric shock should the operator touch the platter?
I've heard of phenomenons such as shaft voltage (which are, if I'm not mistaken, in the order of millivolts) and bearing currents, but I can't really wrap my head around these and don't know whether they are of relevance to this question.
Thank you very much for your help
I'm planning to build a small machine tool using a three-phase AC induction motor (squirrel-cage type) driven by a VFD.
The motor is to drive a metal platter directly, wihout a belt. In other words, the platter will be mounted directly onto the motor shaft.
The operator will have his hands above the platter.
My question is: is there a risk of electric shock should his hands touch the platter for an instant? (for the sake of the discussion, let's ignore mechanical injuries and focus on electrical safety only)
What is more, the machine may be operated in an old building with an old electrical installation, which may have a bad earth connection or even no earth connection at all. So maybe my question should be split into two cases:
(a) Assuming the whole system is perfectly grounded, is there a risk of electric shock should the operator touch the platter?
(b) Assuming the system is not grounded, is there a risk of electric shock should the operator touch the platter?
I've heard of phenomenons such as shaft voltage (which are, if I'm not mistaken, in the order of millivolts) and bearing currents, but I can't really wrap my head around these and don't know whether they are of relevance to this question.
Thank you very much for your help