MotorDoc Vlog 66 Stray Flux Analysis Its Not What You Think It Is

You may have seen these devices that are basically a coil measuring ‘stray flux from the motor indicating machine defects.’ Are these really what is claimed? I’ve reviewed many, many conference and engineering papers alluding to a system that supposedly picks up stray magnetic fields from within the electric motor. They all seem to work in modeling, on paper, and in specially controlled labs but it’s a different story when they are applied in the field. With standards covering EMI, etc. from electric machines this value, if existing at all, would be very small in inverter applications. Instead, you are picking up ground currents from motor leakage, and induced currents from other sources. This means that ground noise, magnetic radiation from other sources even lighting, can all be found on the surface of the electric motor. This Vlog is a live view of what you actually are looking at including a field study at the end.