A constant speed is maintained by varying the discharge (by changing spear position) as the load changes. From the measured discharge (Q), head (almost constant), power developed (P) and overall efficiency (ƞ_o), are calculated and curves are plotted between efficiency (ƞ_o), power (P) and the discharge (Q).

Formulae –

1. Discharge Q= k √h LPM
   K is a constant depends on venturi meter dimensions
   
   

2. Shaft Power/Brake Power developed (B.P)
   B.P = 2πNWRex9.81/60,000 kW
   Where N = speed in RPM
   W = Load applied on brake drum (N)
   R_e = Effective radius of the brake drum in meters
   
   

3. Water Power
   W.P = wQH/1000 kW
   Where w = Specific weight of water (9810 N/m³)
   Q = Discharge in m³/s (as calculated at 1)
   H = Head (of water) acting on Pelton Turbine
   
   

4. Overall Efficiency
   ƞ_o = B.P/W.P
   
   

Procedure

1. Change the load on the Hanger (W) and note the reading of the spring balance (S)
   
2. Adjust delivery valve of centrifugal pump to keep head (H) same and adjust spear position to keep RPM same
   
3. With constant speed and almost constant head note still level reading (Hook Gauge reading)
   
4. By using above mentioned steps, change the load from no load to full load and tabulate the readings as given in the Table 1
   
5. Plot operating characteristics with the data obtained
   
   

Observations -

1. Mean Diameter of the brake drum, D(D_d + D_r) = 200 mm
   Where D_d = diameter of the drum, D_r = diameter of rope
   
2. Speed (RPM) =
   
3. W =
   
4. (Q) = K√h LPM where K = 21.1