example the turbine 105 comprises a number of turbine stages each turbine stage comprises rings of turbine blades in flow direction of the hot gas in the hot gas flow channel a ring of turbine guide vanes 117 is followed by a ring of turbine rotor blades 115 the turbine guide vanes 117 are connected to an inner casing of a stator the turbine rotor blades 115 are connected to the rotor the rotor is connected to a generator for example during operation of the gas turbine air is sucked and compressed by means of the compressor 101 the compressed air is led to the combustion portion 151 and is mixed with fuel the mixture of air and fuel is then combusted the resulting hot combustion gas flows through a hot gas flow channel to the turbine guide vanes 117 and the turbine rotor blades 115 and actuates the rotor the compressor 101 of the gas turbine comprises a compressor inlet duct 102 through which the air is led to the suction portion 109 a conduit connects the compressor inlet duct 102 with the turbine casing through this conduit air with a pressure below 1 bar is guided to the turbine casing the flow direction of this low pressure cooling air through the conduit is indicated in fig1 by an arrow 103 another conduit connects the turbine casing with the compressor casing through this conduit the cooling air is guided away from the turbine casing towards the compressor 101 the cooling air is injected into the compressor 101 in the area of a first.