A pump as turbine (PAT), also known as a pump in reverse, is an unconventional type of reaction water turbine, which behaves in a similar manner to that of a Francis turbine. The function of a PAT is comparable to that of any turbine, to convert kinetic and pressure energy of the fluid into mechanical energy of the runner. They are commonly commercialized as composite pump and motor/generator units, coupled by a fixed shaft to an asynchronous induction type motor unit.