Reheating of Steam under ideal conditions takes place at constant pressure. This means that during the process of reheating, the pressure of the steam remains constant. Let's understand this in detail.

Constant Pressure Process:
A constant pressure process is a thermodynamic process in which the pressure of the system remains constant. During the process, work is done by the system, and the heat energy is supplied to the system. In this process, the volume of the system may change.

Reheating of Steam:
Reheating of steam is the process of heating up the steam after it has passed through the high-pressure turbine. The steam is expanded in the turbine, and its temperature drops. The steam is then reheated to increase its temperature and then passed through the low-pressure turbine. This process improves the efficiency of the power plant.

Ideal Conditions:
Under ideal conditions, the process of reheating of steam is assumed to be reversible, adiabatic, and isentropic. In this process, there are no losses due to friction or heat transfer. The process is assumed to be ideal and perfect.

Constant Pressure in Reheating of Steam:
During the process of reheating, the pressure of the steam remains constant. This is because the steam is heated up in a reheater at constant pressure before it enters the low-pressure turbine. The reheater is designed to maintain the pressure of the steam. If the pressure of the steam changes during the reheating process, it can affect the efficiency of the power plant.

Conclusion:
In conclusion, the reheating of steam under ideal conditions takes place at constant pressure. This is because the reheater is designed to maintain the pressure of the steam during the process of reheating. This process improves the efficiency of the power plant.