We have the customer use MCEMax to measure and diagnosis the condition of wound rotor and they have a good condition for this wound rotor with RTG =5000Mohm and PI = 5.1 with smooth graphic, but after three months later when this motor running in normal condition the customer turn off this motor after that they start again and 2 minutes later the Rotor was burned and this rotor was destroyed ( You can see this in attached file). Could you give me some ideas for this problem to explain for customer? If have short turn in windings of this rotor so How long from they have signals to complete destroyed with your experience? Thanks

P/S: this ABB motor 6.6kV, 350kW