A vapor compression system comprising: a compressor, an evaporator and a condenser connected in a closed loop; a motor connected to the compressor to power the compressor; a motor coolant system configured to cool the compressor motor; the compressor comprising: a first compressor stage and a second compressor stage, the first compressor stage providing compressed vapor to an input of the second compressor stage; the motor coolant system comprising: a first connection in fluid communication with the condenser of the closed loop to deliver refrigerant into a motor cavity, and a second connection with the refrigerant loop to return the refrigerant to an interstage connection having an intermediate pressure, the intermediate pressure greater than an evaporator operating pressure and less than a condenser operating pressure; and a first seal located between the motor cavity and the first compressor stage, and a second seal located between the motor cavity and the second compressor stage, the first and second seal configured to maintain the refrigerant at an intermediate pressure inside the motor cavity; characterized in that the first connection comprises a coolant supply line being configured to directly deliver liquid refrigerant from the condenser expanded to pure vapor into the motor cavity for rotor gap cooling; and wherein the interstage connection is arranged between the the first stage compressor discharge and the second stage compressor suction inlet and the motor cavity is in fluid communication with the interstage connection through a second flow line so as to vent back the refrigerant provided for rotor gap cooling to the interstage connection having an intermediate pressure. a compressor, an evaporator and a condenser connected in a closed loop; a motor connected to the compressor to power the compressor; a motor coolant system configured to cool the compressor motor; the compressor comprising: a first compressor stage and a second compressor stage, the first compressor stage providing compressed vapor to an input of the second compressor stage; the motor coolant system comprising: a first connection in fluid communication with the condenser of the closed loop to deliver refrigerant into a motor cavity, and a second connection with the refrigerant loop to return the refrigerant to an interstage connection having an intermediate pressure, the intermediate pressure greater than an evaporator operating pressure and less than a condenser operating pressure; and a first seal located between the motor cavity and the first compressor stage, and a second seal located between the motor cavity and the second compressor stage, the first and second seal configured to maintain the refrigerant at an intermediate pressure inside the motor cavity; characterized in that the first connection comprises a coolant supply line being configured to directly deliver liquid refrigerant from the condenser expanded to pure vapor into the motor cavity for rotor gap cooling; and wherein the interstage connection is arranged between the the first stage compressor discharge and the second stage compressor suction inlet and the motor cavity is in fluid communication with the interstage connection through a second flow line so as to vent back the refrigerant provided for rotor gap cooling to the interstage connection having an intermediate pressure. a first connection in fluid communication with the condenser of the closed loop to deliver refrigerant into a motor cavity, and a second connection with the refrigerant loop to return the refrigerant to an interstage connection having an intermediate pressure, the intermediate pressure greater than an evaporator operating pressure and less than a condenser operating pressure; and a first seal located between the motor cavity and the first compressor stage, and a second seal located between the motor cavity and the second compressor stage, the first and second seal configured to maintain the refrigerant at an intermediate pressure inside the motor cavity; characterized in that the first connection comprises a coolant supply line being configured to directly deliver liquid refrigerant from the condenser expanded to pure vapor into the motor cavity for rotor gap cooling; and wherein the interstage connection is arranged between the the first stage compressor discharge and the second stage compressor suction inlet and the motor cavity is in fluid communication with the interstage connection through a second flow line so as to vent back the refrigerant provided for rotor gap cooling to the interstage connection having an intermediate pressure.