During operation of the steam turbine, the reduction of condenser vacuum will cause the exhaust steam pressure to increase, the available enthalpy to decrease and at the same time the output of generating unit to reduce; The exhaust cylinder and bearing pedestal expand  by heat, the bearing load distribution changes and the generation unit vibrates; The condenser copper pipe loosens, deformes and fractures due to heat expansion; If the load keeps unchanged, the axial thrust will be increased and the blade will be overloaded, the exhaust steam volume and flow will be reduced and the final stage will produce flow separation and vortex; At the same time a larger vibration force will occur  in a certain parts of the blade, the blade will be possible damaged. Therefore the following measures must be taken if the vacuum reduction is found during operation of unit: 

1. If the vacuum reduction is found, firstly the gauge shall be contrasted. If the vacuum gauge indication decreases and the exhaust steam room temperature increases, it can be identified that the vacuum reduces. If the working condition is unchanged, with vacuum reducing, the load decreases accordingly. 

2. After the vacuum reduction is confirmed, the reasons shall be quickly checked. According to the vacuum reduction, take the corresponding treatment measures. 

3. The standby water jet air ejector or auxiliary air ejector shall be started. 

4. During processing, if the vacuum continues reducing, the load shall be reduced according to the stipulations in order to prevent the temperature of the exhaust steam room overlimitting and to prevent the air safety valve of low pressure cylinder acting. The steam turbine vacuum reducing includes suddenly reducig suddenly reducing and slowly reducing.