This means that one of the electrical windings inside the compressor has broken. When this happens the winding will hit the side of the compressor causing a direct short to ground. Usually this will ignite the oil causing a burnout. This is a bad thing to happen to your system, the compressor will have to be changed and the refrigerant lines will need to be cleaned. If your compressor was out of warranty you will want to replace the entire condensing unit as it is usually cheaper. Cleaning the lines is done with suction line filters and liquid line dryers. In some cases the suction line filters have to be changed multiple times.