position of control or relay ar and fly balls of the centrifugal governor
position of control or relay ar and fly balls of the centrifugal governor shows the position of the piston in the relay cylinder, position of control or relay ar and fly balls of the centrifugal governor, where the turbine is running at the normal speed. sh the load on the generator decreases, the speed of the generator increases. This increas the
d of the turbine beyond the normal speed. The ning meinar which is al ne main shaft will be rotating at an increased speed. Due increase in the speed of live rifugal governor the flyballs move upward due to the increased centrifugal force on then. Due to the upward movement of the flyballs, the sleeve will also move upward. A horizontal ver, supported over a fulcrum, connects the sleeve and the piston rod of the control valve As the eve moves up the lever turns about the fulcrum and the piston rod of the control valve moves downward. This closes the valve V, and opens the valve V, as show in Figure.
This decrease of area of flow will reduce the rate of flow of water
position The oil pumped from the oil pump to the control valve or relay, under pressure will flow through the valve V, to the servo motor (or relay cylinder) and will exert force on the face A of the piston of the relay cylinder. The piston along with piston rod and spear will mover towards right. This will decrease the area of flow of water at the outlet of the nozzle. This decrease of area of flow will reduce the rate of flow of water to the turbine, which consequently recesses the speed of the turbine. When the speed of the turbine becomes nor:nal, the flyballs, lever and piston rod of control valve come to its normal position as show, is Figure 13.7.When the load on the generator increases, the speed of the generator and hence of the turbine decreases. The speed of the centrifugal governor also decreases and hence the centrifugal force acting on the fly balls also reduces. This brings the flyballs in the downward direction. Due to this the sleeve moves downward and the lever turns about the fulcrum moving the piston rod of the control valve in the upward direction. This closes the valve Vy and opens the valve V, The oil under pressure from the control valve will move though valve Vito the servomotor and will exert a force on the face B of the piston. This will ove the piston along with piston rod and spear toward left, increasing arms of flow of water at the quest of the nozzle. This will increase the rate of flow of water to the turbine and, consequently, the speed of the turbine will also increase, till the speed of the Turbine become normal
which regulates the rate of flow through the turbine according
The governing of a turbine is defined as the operation by which the speed of the turbine is kept constant under all conditions of working. It is done automatically by means of a governor, which regulates the rate of flow through the turbine according to the changing load conditions. Governing of a turbine is necessary as turbine is directly coupled to an electric generator, which is required to run at constant speed under all fluctuating loads conditions. The frequency of power generation by a generator of constant numb.: of pair of pqies under all varying conditions shoold be constant. This is only possible when the speed of the generator, under all changing load condition is constant. The speed of the generator will be constant, when the speed of the turbine (which is coupled to the generator) is constant.
When the load on the on generator decreases, the speed of the generator increases beyond the annal need (constant speed). When the speed of the tune else increases beyond the normal of the turbine or the generator is to run at constant (normal) speed the rate of flow of water to the turbine should be decreased till the speed become normal. This process by which the speed of the turbine (and hence of generator) is kept constant under condition of load is called governing.
Gaval Turbine: The jonval is an axial fionde ab the simplest type consist orizontal ring of moving blades into which deter is directed by guide vanes placed ove The flow is regulated by a horizontal sluice, which closes part of the wheel.
This process by which the speed of the turbine
Girad Turbine: There are two types of girad turbines, an axial flow and a radial flow, b are impulse wheels. They may be used for heads up to 1700 ft and have an overall efficients of about 75% the guide passages do not extend over the whole circumference but over two opp quadrants. The water supply is varied by a sliding circular sluice gate, which completely smas uff the flow through the vanes it covers. By turning this sluice gate the fio, ma be stopped th any vanes a required. This preveus any hol hand due to contaction when coming “part gate “The heel of the axial flow is usually plead vertical, the redint flow may be horizand or veridical.
Turbo Impulse wheel. This is a modern type of impulse wheel, which uses a free jet in place of guide vanes in the same manner as in the pelton wheel. This is a high-speed wheel, which is used for medium head and for small and medium output. Its septic speed varies between 3 and 5; overall efficiencies of 85% are obtained from this turbine.
