Refrigerant compressor

A refrigerant compressor for refrigeration plants, comprising a compressor unit driven by a drive unit, wherein at least one of these units is provided with a control unit which is controllable by means of a delivery rate control system in order to control the refrigerant compressor at different delivery rates, wherein an external delivery rate setpoint value is communicated to the delivery rate control system, the delivery rate control system acquires, by means of a sensor, a compressor reference temperature of the compressor unit, in that the delivery rate control system ascertains an operating state value group for acquisition of an operating state of the refrigerant compressor on the basis at least of the acquired compressor reference temperature or the delivery rate and, taking account of specified reference values for differentiating between operating states that are non-critical and critical for the refrigerant compressor, if the value of the ascertained operating state value group based upon the compressor reference temperature permits a critical operating state of the refrigerant compressor, specifies a delivery rate which has as its result an operation of the refrigerant compressor outside of the critical operating states.