The losses occuring in the generator stator winding components viz stator winding, main brushes & phase connetors are dissipated directly through water.
The cooling water being in direct contact with voltage winding, must have an electrical conductivity of order of 0.5 to 1 µΩ .
The stator winding is cooled by closed circuit circulation of low conductivity water ( Demineralised water) through the hollow rectangular conductors which from the cooling system for higher rating (200 MW & above) Generator.
The cooling water from the expansion tank is circulated by two 100 % duty AC motor driven , centrifugal pumps , one working and the other standby.
The pump are electrically interlocked between each other in such a manner that the standby pump automatically starts up in case of water drops in the circuit. In case of the pressure is still less, an alarm signal appears and machine should be tripped.