Sudden changes of load on synchronous motors may sometimes set up oscillations that are superimposed upon the normal rotation, resulting in periodic variations of a very low frequency in speed. This effect is known as hunting or phase-swinging.
Mutual inductance between two coupled coils is given by the relation M = K√L1L2 Where L1L2 = Inductance of the coil K = Coefficient of coupling When K = 1 coils are said to be tightly coupled and if K is a fraction the coils are said to be loosely coupled. Here Kmax =1 Kmin =0 ∴ m ≤ (L1 L2 )0.5
Galvanized steel conductors do not corrode, and possess high resistance. Hence such Wires are used in telecommunications circuits, earth wires, guard wire, stray wire, etc.
Penstock Penstock pipe is used to bring water from the dam to the hydraulic turbine. Penstock pipes are made up of steel or reinforced concrete. The turbine is installed at a lower level from the dam. The penstock is provided with a gate valve at the inlet to completely close the water supply. It has a control valve to control the water flow rate into the turbine.
The total number of the conductor in stranded cable is given by N = 3x2 − 3x + 1 Where x = no. of layer For layer 1 N1 = 3(1)2 − 3(1) + 1 N1 = 1 For layer 2 N2 = 3(2)2 − 3(2) + 1 N2 = 7 In layer 2 no. of conductor = N2 − N1 = 7 − 1 = 6 For layer 3 N3 = 3(3)2 − 3(3) + 1 N3 = 19 In layer 3 no. of conductor = N3 − N2 = 19 − 7 = 12
EXAMIANS